The activities of six bacteriophage T2r+-induced enzymes (thymidylate synthetase, deoxycytidylate deaminase, thymidylate kinase, deoxycytidylate hydroxymethylase, deoxycytidine pyrophosphatase, and dihydrofolate reductase) were measured after dilution of phage-infected Escherichia coli B from 8 X 108 to 2 x 108 cells per ml. The only enzyme activity altered was that of deoxycytidylate deaminase...

Although several values for tissue phosphoglucomutase activites are recorded in the literature, such determinations have been performed without the addition of the coenzyme, a-glucose 1,6-diphosphate (l-3), and occasionally without explicit designation of the optimal concentrations of either or both of the known activators, Mg++ and amino acid (2, 3). Although some of these latter factors have ...

Abstract Physiological fibrinolysis under normal conditions progresses slowly, in contrast to coagulation which is triggered rapidly stop bleeding and defend against microbial invasion. Methods detect abnormalities are less simple poorly standardized compared with common tests. Fibrinolysis can be accelerated by preparing euglobulin from plasma reduce endogenous inhibitors, or adding plasminoge...

Two forms of deoxythymidine kinase from blast cells of acute myelocytic leukemia were identified by electrophoresis. One was associated mainly with the cytoplasm and the other with mitochondria. Both isozymes were separated and purified by differential affinity column chromatography which resulted in 2416- and 1634-fold purification of the cytoplasmic and mitochondrial enzymes, respectively. Af...

Aurintricarboxylic acid (ATA) was found to be a very potent inhibitor of purified rabbit liver phosphofructokinase (PFK), giving 50% inhibition at 0.2 microM. The inhibition was in a manner consistent with interaction at the citrate-inhibitory site of the enzyme. The data suggest that inhibition of PFK by ATA was not due to denaturation of the enzyme or the irreversible binding of inhibitor, si...

Investigation of the substrate specificity of lecithin: cholesterol acyltransferase has been greatly aided by the use of synthetic particles containing the molecular lipid substrates and the apolipoprotein activators of the enzyme. These synthetic particles, in vesicle or disc-like micelle form, are described in some detail noting their preparation, properties, advantages, and limitations as su...

Purified human pancreatic alpha-amylase (alpha-1,4-glucan 4-glucano-hydrolase, EC 3.2.1.1) was found to be stable over a wide range of pH values (5.0 to 10.5) with an optimal pH for the enzymatic activity of 7.0. The Michaelis constant of the enzyme at optimal pH and assay conditions was found to be 2.51 mg per ml for soluble starch. Halide ions were required for the activity of the enzyme wher...

The secretion of plasminogen activators has been implicated in the controlled extracellular proteolysis that accompanies cell migration and tissue remodeling. We found that the human plasminogen activator urokinase (Uk) (Mr 55,000 form) binds rapidly, specifically, and with high affinity to fresh human blood monocytes and to cells of the monocyte line U937. Upon binding Mr 55,000 Uk was observe...

activators though less so than magnesium. Potassium ions are inactive in this respect. 3. The pH optimum of the enzyme for the forward reaction, i.e. the splitting of phosphocreatine in the presence of adenylic acid lies in the range of 5*9-7; phosphocreatine is split optimally at the same pH range when adenosinediphosphate is used as the phosphate acceptor. 4. Preparations from brain also cata...