We have evaluated and modified a current method for estimating 8-aminoIevulinic acid dehydratase (5-aminolaevulinate hydro-lyase, EC 4.2.1.24) activity in blood, so as to adequately control the pH of the enzyme-substrate solution at the optimum throughout the incubation period. This has improved the sensitivity and reliability of the assay. Also, N-ethylmaleimide has been substituted for a pote...

The protease produced by Mucor pusillus was recovered from a wheat bran medium by treatment with ammonium sulfate, ethyl alcohol, gel filtration and ion-exchange chromatography. The yield of the enzyme was 55%. The overall increase in the specific activity of the protease was 34-fold. The purified protease was most active at pH 3.8 and 5.6 against hemoglobin and casein, respectively. Optimal hy...

The product of the dcm gene is the only DNA cytosine-C5 methyltransferase of Escherichia coli K-12; it catalyses transfer of a methyl group from S-adenosyl methionine (SAM) to the C-5 position of the inner cytosine residue of the cognate sequence CCA/TGG. Sequence-specific, covalent crosslinking of the enzyme to synthetic oligonucleotides containing 5-fluoro-2'-deoxycytidine is demonstrated. Th...

The properties of acyl-CoA: sn-glycerol-3-phosphate acyltransferase (EC 2.3.1.15) from pigeon liver particles have been studied. The apparent Km for snglycerol 3-phosphate was 50 PM. Acyl-CoA inhibited the enzyme at concentrations exceeding 60 PM. This inhibition can be overcome by adding extra protein. The enzyme was inhibited by thiol-binding agents. Protection from thiol-binding agents is ac...

An extracellular nuclease produced by Staphylococcus aureus1-3 has been shown to contain 149 amino acid residues (mol wt, 16,807) and to lack both sulfhydryl groups and disulfide bonds (Fig. 1).3-5 The enzyme catalyzes the cleavage of both DNA and RNA to yield 3’-nucleotides.2s 3 The absolute requirement for Ca++ l* 2s 6 may be explained by the interdependency of Gaff and nucleotide binding to ...

Alcohol acetyltransferase (AATase) catalyzes the esterification of isoamyl alcohol by acetyl coenzyme A. The enzyme was solubilized from the microsomal fraction of Saccharomyces cerevisiae Kyokai No. 7, using Triton X-100 and then purified by a series of chromatographic separations: Poly Buffer Exchanger 94 (PBE94), DEAE Toyopearl, Toyopearl HW60, hydroxyapatite, Octyl-Sepharose CL-4B, and hexa...

Dihydrofolate reductase (DHFR) (5,6,7,8-THF: NADDP+ oxidoreductase, EC 1.5.1.3) was purified 205-fold to apparent homogeneity from the crude extracts of Lactobacillus leichmannii. It has UV absorption maxima at 280 nm, M(r) of 20,000, Stokes radius of 0.34 nm and a S20.w value of 0.12 S. The preparation showed the presence of 168 amino acid residues with threonine and lysine as the NH2- and COO...

Chlorophyllase from Ailanthus altissima leaves has been purified 63-fold by a combination of heat treatment, ultracentrifugation, gel filtration, and chromatography on diethylaminoethyl cellulose. While the enzyme is inhibited to some degree by Triton X-100, a modification of the assay procedure of Klein and Vishniac has been shown to be far superior to the use of aqueous acetone systems. The e...

The cysteine-directed reagent N-ethylmaleimide rapidly and completely inactivates pyruvate oxidase. This inactivation is correlated with the reaction of one cysteine residue per enzyme monomer. In the presence of the cofactor, thiamin pyrophosphate, the enzyme is not inhibited by N-ethylmaleimide. Furthermore, the N-ethylmaleimide-inactivated enzyme exhibits a very low affinity for the cofactor...