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During the submerged cultivation of Bacillus thuringiensis var. thuringiensis in 300- and 3000-liter fermentors, lysis occurred at the end of the exponential phase of growth. New vegetative cells were subsequently formed which usually sporulated. At time of lysis, the amount of soluble sugar was 1-12 g/liter, pH value ... |
Strictly anaerobic and facultatively anaerobic strains of "corroding bacilli" failed to produce any pathological symptoms when injected into white mice and no viable organisms could be recovered after 7 days. However, when these same strains were coupled with certain other living bacteria or certain sterile bacterial e... |
Four distinct peptide hydrolases (EC 3-4) have been characterized in guinea-pig epidermis; these are cathepsin B1, cathepsin C, cathepsin D and arylamidase. Their properties are consistent with those of lysosomal enzymes. Cathepsin E was not detected. |
1. The solubility of fatty acids in aqueous media containing bile salts alone and in admixture with either lecithin (phosphatidylcholine) or phosphatidylethanolamine was determined. 2. Over the pH range 2-0-7-4, the order of fatty acid solubility in aqueous solutions containing bile salts was linoleic greater than olei... |
1. The solubility of fatty acids in aqueous solutions containing bile salts and lysolecithin at pH values between 2-0 and 7-4 was studied. Both the 1-acyl and 2-acyl isomers of lysolecithin increased the solubility of fatty acids to the same extent, the order of solubility being linoleic greater than oleic greater than... |
The low molecular weight folate binding protein (FABP) has been purified 1000-fold to a specific activity of 7.2 gamma g of pteroylglutamic acid (PGA) bound per mg of protein. This purified FABP represents two protein bands that bind PGA on polyacrylamide disc gel electrophoreis, elutes from DEAE-cellulose in 0.001 M p... |
Two immunoglobulins, IgA(K) and IgG(K), were isolated from the serum of a single patient with two monoclonal components (biclonal proteins). After chain separation, the light chains from each molecule were found to be identical by the following criteria: electrophoretic mobilities under various pH and dissociating cond... |
As shown previously, proteinases frequently associated with plasma albumin samples catalyze a very limited and specific cleavage of the albumin molecule when it exists in the F conformational state near pH 3.7. The primary proteolytic product, BPA, has a molecular weight similar to or identical with that of the parent ... |
Extracts of acetone-ether powders of bovine thoracic aorta contain lipase activity which has an alkaline pH maximum (7.8-8.4) and is stimulated 4-10-fold by adding serum or isolated apolipoprotein-glutamate to the assay mixture. Serum activation is completely reversed by isolated apolipoprotein-serine or apolipoprotein... |
Purine nucleotide pyrophosphotransferase was purified to apparent homogeneity from a culture filtrate of Streptomyces morookaensis. It is a monomeric protein with a molecular weight of 24 000-25 000, and its isoelectric point is 6.9. The enzyme synthesizes purine nucleoside 5'-phosphate (mono, di, or tri) 3'-diphosphat... |
A protein kinase (EC 2.7.1.37) which phosphorylates histones was purified partially from the soluble fractions of cultured plant cells. The optimum pH was 7.5 to 9.0. The activity wasnot stimulated by exogeneous cyclic AMP. It was thermolabile and completely dependent on the presence of Mg2+ or Mn2+ for activity. p-Chl... |
Adenosine triphosphate : nicotinamide mononucleotide adenylyltransferase (EC 2.7.7.1) has been purifiec approximately 3500-fold from an extract of pig liver nuclei to a specific activity of 40 mumol of NAD+ per min per mg protein. The enzyme was found to have a molecular weight of 203 000, a frictional ratio of 1.6 and... |
Porcine pancreas synthesizes a prephospholipase A2 which occurs in a 5 : 95 ratio compared with the more abundant zymogen of the same enzyme (phosphatide-acylhydrolase; EC 3.1.1.4). These two prephospholipases could be well separated by CM-cellulose chromatography. Both the active and the zymogen form of the isoenzyme ... |
The existence of cyclic GMP phosphodiesterase (EC 3.1.4.-) was demonstrated in silkworm larva by gel filtration of the homogenate. The cyclic GMP phosphodiesterase was separated from cyclic AMP phosphodiesterases by column chromatography on hydroxyapatite and Sephadex G-200. The enzyme has a molecular weight of approx.... |
(11 Cell extracts and extracellular culture fluids of species of the yeast genus Schizosaccharomyces exhibited exo-beta-(1 leads to 3)- and exo-beta-(1 leads to 6)-glucanase (EC 3.2.1.-) activities. (2) Using a combination of Sephadex G-100 and DEAE-cellulose chromatography, the exo-beta-(1 leads to 3)-glucanases from ... |
Maltohexaose producing amylase (EC 3.2.1.-) is the fourth known exo-amylase, the three previously known being glucoamylase, beta-amylase and Pseudomonas stutzeri maltotetraose producing amylase. The enzyme after release from Aerobacter aerogenes cells by 0.1% sodium lauryl sulfate extraction was purified by ammonium su... |
N-Bromoacetyl-beta-D-galactosylamine is an irreversible inhibitor of the 'acid' and the 'neutral' beta-galactosidases (beta-D-galactoside galactohydrolase, EC 3.2.1.23) of human liver. The inactivation of acid beta-galactosidase appears to involve a group with a pKa = 4.5. The inhibition of neutral beta-galactosidase o... |
An arabinanase was purified from the culture fluid of Bacillus subtilis F-11. The process was as follows: salting out by (NH4)2SO4, repeated chromatography on hydroxy apatite and gel filtration on Sepharose-6B. The purified enzyme was demonstrated to be homogeneous by disc electrophoresis. The enzyme was found to be ac... |
The major group of aminopeptidases (EC 3.4.11.-) of intermediate electrophoretic mobility, from Tineola bisselliella larvae, hav been fractionated into six bands by preparative polyacrylamide gel electrophoresis and the properties of these fractions investigated. They resemble each other in their pH optima of 8.2, thei... |
1. An activator of the (Ca2+ plus Mg2+)-stimulated ATPase present in the human erythrocytes (membrane) has been isolated in soluble form from hemolysates of these cells. Partial purification has been achieved through use of carboxymethyl-Sephadex chromatography. The resulting activator fraction contained no hemoglobin ... |
Optical and ESR spectra of erythrocyte superoxide dismutase denaturated with acid and alkali are described. Sharp changes in activity and spectra were found. "Residual" activity of alkaline denaturated protein was higher than of acidic denaturated sample. It is suggested that covalent bonding copper-nitrogen is essenti... |
The characteristics of light scattering of cell suspensions in norm (pH 7,2, t=20degreesC) and upon external influences (change of pH and increase of tdegree). The turbidity tauapproximatelylambda-n and n=0,2--0,3 for cells in norm. After cell damage n increases. Dependence of n correlates with the increase of some inj... |
The protein and proteolipid complexes and oligomycin insensitive soluble ATPase were prepared from rat liver mitochondria. The incubation of soluble ATPase with protein and proteolipid complexes resulted in restoration of ATPase sensitivity to oligomycin at room temperature. The process of reconstruction depended on pH... |
Acetyl-CoA-synthetase was isolated from cells of St. aureus 209-P. The method of isolation and partial purification of the enzyme is worked out. Km values of the enzyme for acetate, CoA and ATP are calculated. p-Chloromercuribenzoate and monoiodoacetate were shown to inhibit the enzyme activity. The enzyme activity is ... |
Constants of inactivation rate of horseradish peroxidase (HRP) apo-HRP and apo-HRP-protoporphyrin (PP) are estimated at the pH range 2.8-12.8 and 25 degrees C. Two ionogenic groups (acid and alkaline) are detected on cases of HRP and apo-HRP, which are responsible for stable HRP conformation. HRP stability within the p... |
Proteindisulphide reductase is isolated and partially purified from wheat seedlings and some properties of the enzyme are studied: pH optimum is 7.4; temperature optimum - 37 degrees C; Km = 2.6-10(-4)M for the substrate (wheat albumin); Km = 7.5-10(-5) M for coenzyme (NADP-H). The enzyme is specific for NADP-H and is ... |
Carboxymethylcellulose, carboxymethylchitin, sulfoethylcellulose and dextrane sulfate interact with pancreatic ribonuclease. In comparison with ribonuclease activity the activity of formed complexes changes differently at the stages of transesterification and hydrolysis, and at each stage the effect of polymers on ribo... |
Quantitative kinetic data are given on the oxidation reaction of dioxyfumaric acid (DFA) with atmospheric oxygen in the presence of horseradish peroxidase (HRP) depending on pH. Activation constants of oxidation with hydrogen peroxide and Mn ions are determined at pH 3.0. Autocatalytic character of FRA oxidation is sho... |
An improved procedure of purification of serinesulfhydrase from chicken liver is described. Preparations of enzyme (700-fold purification with the yield of 40 per cent from total activity) have been obtained homogeneous on polyacrylamide gel electrophoresis. Molecular weight of serinesulfhydrase is 90.000; 1 mole of en... |
Specificity of chromatographically homogenous extracellular alkaline RNAase from Pen. crysogenum 152A on RNA, synthetic polynucleotides, dinucleosidemonophosphates and nucleoside-2',3'-cyclophosphates is studied. The enzyme is found to release from RNA guanosine-3'-monophosphate and guanosine-2',3'-cyclophosphate only.... |
It has been shown that for the reaction catalyzed by "biodegradative" L-threonine dehydratase from E. coli strains K-12 and 980 in 0.5 M phosphate-carbonate buffer, pH 8.4 and pH 9.5, the plots of initial reaction rate (v) versus the initial substrate concentration ([S]0 are characterized by several inflection points, ... |
The modified procedure for rabbit skeletal muscle phosphofructokinase (PFK) purification is worked out utioizing the method of specific elution from DEAE-cellulose in 0.1 M tris-EDTA-phosphate pH 8.0 with 10 mM citrate. By the latter procedure PFK can be resolved into fractions A, B and C which are eluted specifically,... |
Separation and partial purification of isoenzymes of phosphorylase B from skeletal muscles of lamprey (Lampetra) and carp (Cyprinus carpio) was carried out. Isoenzyme I was adsorbed on DEAE cellulose and eluted by KCl; isoenzyme II was not adsorbed on DEAE cellulose. A number of kinetic characteristics of phosphorylase... |
A method of isolating polynucleotidephosphorylase (PNPase) containing polyribosome fraction from rat liver is described. PNPase is found to be bind to RNA in polyribosomes with weak electrostatic bonds which are easily broken down in a weak alkaline medium with ionic strength more than 0.1 beta-22P-labelled ADP, GDP, U... |
The effect of NADH, succinate and ATP on the sensitivity of a number of energy-dependent functions of submitochondrial particles ot phospholipases A, C and D has been studied. It has been shown that in the conditions of oxidation of NADH and succinate by oxygen and also of ATP hydrolysis, the decrease in the phosphoryl... |
A dependency of fluorescence parameters of histidinedecarboxylase (HDC) from Micrococcuc sp. n. on pH values is studied. Native HDS has a short-waved maximum position (325 nm) and a small half-width of the fluorescence spectrum (48nm). The change in the quantum yield of the enzyme fluorescence was parallel with the cha... |
When a mixture of the eighteen proteinous amino acids are suitably heated in the dry state with seawater salts, a copolyamino acid results. One fraction of this polymer is found, through isoelectric focusing, to consist of a mixture of acidic and basic proteinoids, each of sharply limited heterogeneity. When one fracti... |
In energy transducing systems the direction of energy transfer is proposed to be maintained by the synchronized turnovers of the conformational change of one protein coupling up to affect another. Catalysis by those systems implies, therefore, that under new space restrictions the groups of the transducing enzyme incre... |
Subtilisin BPN' was immobilized to porous glass via isothiocyanate coupling. The pH optimum of the enzyme was shifted to the alkaline side on binding. This effect was more pronounced with ethyl lactate than with N-tosyl arginine methyl ester (TAME). Presumably, the shift is a reflection of the negative charge on the su... |
The profiles thus established may be utilized for investigations of an organism's relationship to its microenvironment including metabolic shifts and pathways. Areas of maximum respiratory activity, enzyme production, enzyme degradation, and attainment of the stationary phase are quite evident; however, duration and ma... |
Over several years sera were collected from 14 heterophil-positive students or patients who did not fulfill minimal hematologic criteria for infectious mononucleosis (I.M.) The specificity of these heterophil reactions for I.M. was investigated by determining antibodies to Epstein-Barr virus-determined antigens, i.e., ... |
Bone-marrow transplantation (BMT) from an unrelated, HL-A-phenotype-identical, MLC-negative donor was performed in a 31 year old woman with severe longlasting aplastic anemia. In vitro assays failed to demonstrate humoral or cellular sensitization of the recipient against donor-type antigens. Following conditioning wit... |
1 The concentrations of noradrenaline and adrenaline in various organs, arterial plasma and venous outflow from isolated hearts of adult chickens have been determined. 2 The relative adrenaline concentrations (percentage of the sum of noradrenaline and adrenaline) in the heart (33%), spleen (16%) and brain (26%) were h... |
1 The antiarrhythmic, haemodynamic and metabolic effects of a new amino steroid, ORG6001, have been investigated in experimental acute myocardial infarction in anaesthetized greyhounds. 2 ORG6001 administered either intravenously (2-10 mg/kg) or orally (50 mg/kg) significantly reduced the incidence of ventricular ecto... |
1 The use of radioactive microspheres is described for the measurement of cardiac output in anaesthetized rabbits and its redistribution after the administration of drugs which lower blood pressure. 2 Hydralazine increased peripheral vascular conductance by 123%. The vascular beds in which it had most effect were those... |
The effect of attitudes of therapists, patients and researchers on the conduct and outcome of combined drug and psychotherapy research was examined in a brief crisis-oriented psychotherapy clinic. Seventy-seven consecutive patients were given one of two anti-anxiety drugs or a placebo in conjunction with the typical ps... |
A transplantable mouse testicular teratoma (OTT 6050) which displays a spectrum of neuroepithelial differentiation was evaluated biochemically for concentrations of cyclic AMP (cAMP), serotonin (5-HT), and enzymes involved in the metabolism of the biogenic amines and acetylcholine. These values were compared between te... |
To examine the regulation of development of end organ innervation the superior cervical ganglion (SCG), and two of its target organs, the iris and pineal gland, were studied using biochemical and histofluorescent approaches. During postnatal ontogeny the activity of tyrosine hydroxylase (T-OH), which is localized to ad... |
Rat placental alkaline phosphatase (EC 3.1.3.1), a dimer of 135,000 daltons, is strongly activated by Mg2+. However, Zn2+ has to be present on the apoenzyme to obtain this activation. Mg2+ alone is unable to reconstitute functional active sites. Excess Zn2+ which competes for the Mg2+ site leads to a phosphatase with l... |
A kinetic study of procine chymotrypsin A-pi revealed two characteristic properties of this type of chymotrypsin: 1. Porcine chymotrypsin A-pi, like bovine chymotrypsin B-pi does not bind proflavin, which is a competitive inhibitor of bovine trypsin and chymotrypsin A-alpha. 2. The pH profiles of the steady-state param... |
The free and bound forms of alpha,alpha-trehalase (EC 3.2.1.28) of the honey bee thorax were separated and the bound enzyme was solubilized by raising the pH to 8.0 for 10 h. Both enzymes were purified. They were homogeneous as determined by several electrophoretic criteria. It was found that the two enzymes had very s... |
Immunotherapy of cancer is of interest to oncologists because it is specifically directed to cancer cells, sparing normal cells. While it is ineffective in most patients, especially those with widespread metastatic disease, it occasionally produces good results. Each of the available methods has inherent problems and, ... |
L-[alphaS,5S]-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (NSC-163501), an antibiotic elaborated by Streptomyces sviceus, has been shown to be a powerful inhibitor of many mammalian and bacterial reactions involving the transfer of nitrogen from the gamma-carboxamide of L-glutamine. Thus, the utilization of... |
The antitumor and immunosuppressive activities of the lankacidin-group antibiotics were studied in mice. Seventeen of 29 newly prepared lankacidin-group antibiotics, including 14-derivatives of lankacidin C, lankacidinol, isolankacidinol, and lankacidinol 14-acetate, possessed considerable antitumor activity against as... |
Previous studies on renin release by an in vitro system of rat kidney slices, which is devoid of hemodynamic influences, have provided evidence that renin release is stimulated by a beta-adrenergic mechanism. We used this system to study effects of tyramine (an indirectly acting amine capable of displacing endogenous c... |
Sera from patients with hepatobiliary disorders were selected to represent a wide range of activity of gamma-glutamyltransferase (EC 2.3.2.2). Samples were stored at 4 degrees C and periodically tested for as long as nine weeks, others at -6 degrees C for as long as 40 weeks. The frozen-stored samples were thawed and t... |
Continuous monitoring of heat denaturation of a mixture of alkaline phosphatase isoenzymes at 60 degrees C and pH 7.5 permits the simultaneous direct identification and quantitation of three isoenzymes: the placental isoenzyme, the L-phenylalanine-sensitive intestinal isoenzyme, and the liver isoenzyme (hepatocytic). T... |
An optimized end-point method that requires little sophisticated equipment is described for estimating serum cystyl-aminopeptidase during pregnancy. S-Benzyl-L-cysteine-4-nitroanilide is used as the substrate. |
I describe a simple, single-tube batch fractionation procedure for separating MM and MB isoenzymes of creatine kinase on a macroporous strong anion exchanger (AG MP-1, Bio-Rad Laboratories). The isoenzymes can be separated in less than 3 min, with a resulting dilution of the serum with no more than an equal volume of b... |
It is demonstrated that urinary tryptamine decreases significantly with increasing urinary pH. This effect becomes important at a urinary pH of 6.5 and over. |
Urinary gamma-glutamyl transpeptidase (gamma-GT) has been found to be stable when stored at room temperature and 4 degrees C. Activity is lost rapidly when urine is frozen but prior dialysis will prevent this loss. Urea is the major factor responsible for the loss of activity; albumin is protective at concentrations of... |
The purpose of the present study was to evaluate the properties of beta-glucuronidase (EC 3.2.1.31) in human synovial fluid. It was shown to have a pH requirement of 5.0 and a KM value of about 8.0 - 10(-3) M using phenolphthalein beta-glucuronide as the substrate. At low substrate concentration an endogenous inhibitor... |
A 12-year-old girl of Spanish origin was found to be double heterozygote for a deficient GP I variant (GP I Barcelona) and for a silent GP I gene. The mother was heterozygote for GP I Barcelona and the father was heterozygote for the silent gene. GP I Barcelona was a fast variant (116%) with an increased isoelectric po... |
A method is described for detecting the simultaneous presence of Fc and C3 receptors on mouse spleen cells. A proportion of both T cells and non-T cells bear both receptors. Both T-cell and non-T-cell Fc receptors were blocked by aggregated mouse IgG2 to the same degree. C3, but not Fc, receptors were blocked by factor... |
Because of reports of fluroxene toxicity in man, the effect of phenobarbital treatment on the toxicity and metabolism of fluroxene was studied in 9 rhesus monkeys. Six monkeys that were exposed to a mean calculated alveolar fluroxene concentration of 5.8% for 4-hr periods up to a total of 16 hr showed no evidence of to... |
The effectiveness of intravenously administered propranolol in antagonizing the chronotropic effect of isoproterenol and exercise has been investigated, and has been found at all times to be a predictable function of its plasma concentrations according to the classical drug-receptor theory for competitive antagonism. T... |
Lorazepam, a new benzodiazepine, was compared with a standard surgical premedicant, pentobarbital. In a double-blind study in 128 patients, lorazepam, 2 and 4 mg, and pentobarbital, 50 and 100 mg, were given intravenously in a randomized sequence. Significant differences were noted; lorazepam was found to provide great... |
The question of pH or flow dependence for the renal elimination of procainamide (PCA) was studied under 4 conditions in each of 4 subjects. Each subject received 500 mg of PCA intravenously at weekly intervals while in a state of (1) acid load (NH4Cl) and water deprivation, (2) acid load and water excess, (3) alkali lo... |
1. A retrospective cross-sectional study was carried out on data derived from single 24 h urine collections from 246 male idiopathic calcium stone-formers. 2. The daily urine volume and pH and the exretions of calcium, oxalate, phosphate, creatinine and magnesium were related to the time of year when the urine was coll... |
138 patients with panarteritis of the aorta and its branches were examined, and the clinical and morphological findings were compared. The disease is more widespread than has been assumed so far, and is more frequent in young women. Localization of the process in the abdominal aorta with involvement (stenosis) of renal... |
Fifty-eight neurotic patients with intense anxiety were treated with either lorazepam or diazepam in a double blind between-patients trial. Statistical analysis indicated that the two groups were homogeneous before treatment and that the results of treatment were similar for both drugs. According to the global rating o... |
The presence of p-chlorophenoxyacetamide was detected in the urine of man receiving iproclozide [1-(p-chlorophenoxyacetyl)-2-isopropylhydrazine]. This new metabolite was identified by combined gas-liquid chromatography-mass spectrometry and by comparison with the synthetic compound. An appropriate procedure for the ext... |
Repeated oral treatment of male rats with piperazine-substituted phenothiazine drugs in doses of 25 mg/kg or more daily led to an accumulation of metabolites containing an ethylenediamine group instead of the piperazine ring. These products of ring degradation with and without removal of the N-alkyl group were found, t... |
5-(2'4'-Difluorophenyl) [carboxy-14C]salicyclic acid (MK-647) was quickly and completely absorbed in rats, dogs, and man. Peak levels of plasma radioactivity occurred in 1-2 hr after oral administration. The dose was 10 mg/kg in rats and dogs, and 50 or 500 mg in man. Most of the drug in plasma was intact MK-647 which ... |
The biotransformation of 14C-triflubazam (ORF 8063; 1-methyl-5-phenyl-7-trifluoromethyl-1H-1,5-benzodiazepin-2-4-[3H,5H]-dione) was investigated in rats, dogs, and monkeys. Urinary metabolites, representing 65, 74, and 87%, respectively, of the total urinary radioactivity excreted by these three species, were isolated ... |
After oral administration of 14C-labeled amobarbital to healthy subjects, most of the radioactivity was recovered in urine and only 4-5% in feces over a period of 6 days. No unchanged amobarbital was excreted. Two major metabolites were found and isolated. One was 3'-hydroxyamobarbital, which has been previously identi... |
Gas chromatography-mass spectrometry was used to identify metabolites of spironolactone in human blood and urine. In three healthy men about 20% of the radioactivity was excreted in the urine within 24 hr after an oral dose of [20-3H]spironolactone (200 mg + 200 muCi). About half of this radioactivity was extracted wit... |
The metabolism of 14C-griseofulvin has been compared in rat liver microsomes, isolated perfused rat livers, and rats with bile duct cannulas. In all three preparations, 4-desmethylgriseofulvin and 6-desmethylgriseofulvin were the major metabolites. The ratio of total 4-desmethylgriseofulvin to 6-desmethylgriseofulvin f... |
The mixed-function oxidation of 14C-labled 2-acetylaminofluorene (AAF) was investigated in placental and fetal tissues of humans and monkeys (Macaca nemestrina) in vitro. The major metabolite formed in most tissues was 7-hydroxy-AAF. Rates of the hydroxylation reactions varied widely among the tissues investigated and ... |
An increase in the metabolism of phenacetin to N-acetyl-p-aminophenol is correlated with benzo[a]pyrene hydroxylase induction by 3-methylcholanthrene among several inbred mouse strains. While the magnitude of induction of phenacetin O-dealkylation is considerably less than that of benzo[a]pyrene hydroxylation, the data... |
The enhancing effect of metyrapone upon the p-hydroxylation of acetanilide has been confirmed with the use of a new gas-chromatographic method for the determination of acetaminophen. This effect has been shown not to be due to inhibition of hydrolysis of acetaminophen or interference with its determination, or to prefe... |
Radioactive carbaryl, carbofuran, parathion, leptophos, and DDT were added to cigarettes and the mainstream smoke was directed to the lungs of rats via the trachea. Total radiocarbon transfer to the lungs ranged from 9 to 15% of that in the tobacco burned during a smoking process involving eight 5-ml puffs. Exhalation ... |
2-[4-(2,2-Dichlorocyclopropyl)phenoxy]-2-methylpropanoic acid, Win 35,833, was readily absorbed after oral administration; in rats, rhesus monkeys, and human volunteers, peak concentrations of drug in plasma were attained within 2 hr of medication. The time-concentration curve of administered drug was biphasic in monke... |
The absorption of dl-methadone from the gastrointestinal tract of the Sprague-Dawley rat was examined by the in vivo segment technique. Duodenal absorption, measured as a function of time and dose, followed first-order kinetics with a half-life of 15.6 min. Absorption was not influenced by prior or concomitant administ... |
The 24-hr LD50 of colchicine in newborn rats is 0.24 mg/kg, which is about 1/10 that observed in the adult. The 24-hr LD50 of colchicine was relatively constant in rats over 25 days of age. In an attempt to determine the mechanism of the increased sensitivity of the newborn rat to the toxic action of colchicine, the di... |
A polyoxypropylene-polyoxyethylene block copolymer of about 4750 daltons (Poloxamer 108, Pluronic F-38) used in a new protein fractionation procedure may be infused into patients receiving therapeutic plasma fractions. We studied the disposition and pharmacokinetics of Poloxamer 108 in rats as an initial step towards u... |
The uptake, metabolism, and release of aldrin and dieldrin by the lungs were studied by use of isolated perfused rabbit lungs that were artificially ventilated and perfused through the pulmonary artery. Both recirculating and single-pass experiments were conducted using an artificial medium as perfusate. Aldrin accumul... |
The nature of the inhibitory effects of the major metabolite of diphenylhydantoin, 5-(p-hydroxyphenyl)-5-phenylhydantoin (HPPH), on the in vitro metabolism of ethylmorphine and aniline by rat hepatic microsomes was examined. The N-demethylation of ethylmorphine was competitively inhibited by HPPH, whereas inhibition of... |
The effect of Walker tumor on sulphacetamide distribution was studied in rats 21 days after tumor implantation in a hind leg. After oral administration of sulphacetamide (5 and 20 min), the concentration of the drug was found to be lower in the plasma and liver of tumor-bearing rats when compared with that of control g... |
Cytochrome P-450 was assayed in rat liver homogenates and microsomes in order to calculate microsomal recoveries and correct for losses during ultracentrifugation or sedimentation in presence of CaCl2. The values obtained for corrected microsomal protein in untreated female Sprague-Dawley rats were between 40 and 50 mg... |
Because of increasing evidence for the heterogeneity of polypeptide hormones, studies of the molecular species of human placental lactogen (hPL) were initiated. When extracts of freshly delivered human placentas were passed over Sephadex G-100 in 0.05M ammonium carbonate, three immunoreactive peaks were detected. In ad... |
The transfer of 35SO4= from water to air by bursting bubbles was studied as a function of three levels each of three variables in a bubbling solution. The variables were pH, surfactant concentration, and Na2 35SO4 concentration. One combination of the above variables was also studied at three different temperatures. St... |
Epileptiform after discharges evoked by repetitive electrical stimulation of chronically isolated cortical slabs (cat) were shortened by low doses of phenobarbital but not affected by hypnotic doses of pentobarbital. Both pentobarbital and phenobarbital raised threshold and lowered spike amplitude in isolated sciatic n... |
Horse liver alcohol dehydrogenase was reacted with glyoxal at different pH values ranging from 6.0 to 9.0. At pH 9.0 the enzyme undergoes a rapid activation over the first minutes of reaction, followed by a decline of activity, which reaches 10% of that of the native enzyme. Chemical analysis of the inactivated enzyme ... |
In delta-chymotrypsin the reactivity of methionine-192 towards p-nitrophenacyl bromide is strongly reduced when the alpha-amino group of isoleucine-16 has been acetylated. Since acetylation of isoleucine-16 brings delta-chymotrypsin to a conformation similar to its alkaline one this suggests that methionine-192 should ... |
The kinetic mechanism of action of octopine dehydrogenase was investigated. This enzyme catalyses the reversible dehydrogenation of D-octopine to L-arginine and pyruvate, in the presence of nicotinamide-adenine dinucleotide. Initial velocity and product inhibition studies were carried out in both directions. Most of th... |
1. The steady-state kinetics of the interconversion of CO2 and HCO3 catalyzed by human carbonic anhydrase C was studied using 1H2O and 2H2O as solvents. The pH-independent parts of the parameters k(cat) and Km are 3-4 times larger in 1H2O than in 2H2O for both directions of the reaction, while the ratios k(cat)/Km show... |
Two isoenzymes of an NADP+ -dependent cinnamyl alcohol dehydrogenase and an NAD+ - dependent aliphatic alcohol dehydrogenase were extracted from cell suspension cultures of soybean (Glycine max L., var. Mandarin) which form lignin during growth. These enzymes could be separated from each other by chromatography on DEAE... |
The presence of activators(AMP and sulphate) or inhibitors(acetyl-CoA) has no influence on the Hill coefficient of the S-shaped [pyruvate]--velocity curve of either the pyruvate-NAD+ overall reaction(h equals 2.5) or that of the pyruvate-K3Fe(CN)6 ACTIVITY OF THE FIRST ENZYME (H EQUALs 1.3). pH STUDIES INDICATED THAT T... |
Arginine decarboxylase which makes its appearance in Lathyrus sativus seedlings after 24 h of seed germination reaches its highest level around 5-7 days, the cotyledons containing about 60% of the total activity in the seedlings at day 5. The cytosol enzyme was purified 977-fold from whole seedlings by steps involving ... |
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