Alton Meister

Studies on conversion of phenylalanine to tyrosine in phenylpyruvic oligophrenia.

Summary A homogenate of a biopsy specimen of liver obtained from a patient with phenylpyruvic oligophrenia did not catalyze detectable conversion of phenylalanine to tyrosine, under conditions whereby liver homogenates obtained from normal individuals were active in catalyzing such conversion. Addition of a fraction prepared from rat liver (which exhibited relatively low activity alone) to the inactive phenylketonuric liver homogenate resulted in striking activation of the conversion of phenylalanine to tyrosine.

Determination of D-amino acid oxidase activity in insect tissues using D-allohydroxyproline as substrate.

Abstract This paper describes a sensitive procedure for the determination of d -amino acid oxidase activity using d -allohydroxyproline as the substrate. The substrate is enzymically dehydrogenated to Δ 1 -pyrroline-4-hydroxy-2-carboxylic acid, which, on acidification, is converted to pyrrole-2-carboxylic acid. Pyrrole-2-carboxylic acid itself reacts very slowly, if at all, with p -dimethylaminobenzaldehyde. However, after decarboxylation to pyrrole, it reacts rapidly to yield a red product. By means of this procedure, 10 mμmoles of pyrrole may be detected. Homogenates prepared from various organs of six insect species, the wax moth Galleria mellonella , the blue-bottle fly Calliphora erythrocephala , the large milkweed bug Oncopeltus fasciatus , the American cockroach Periplaneta americana , and the cockroaches Byrsotria fumigata , and Eurycotis floridana were assayed by this procedure. Activity was found in the fat body, midgut, and Malpighian tubules of all of the species examined. The muscle of Oncopeltus and the testes of Oncopeltus, Byrsotria , and Periplaneta also exhibited activity. No significant differences were found when enzyme activity was compared in Eurycotis floridana reared under sterile and non-sterile conditions.

Purification and properties of l-valyl-sRNA synthetase from Escherichia coli

Abstract l -Valyl-sRNA synthetase ( l -valine:sRNA ligase (AMP), EC 6. i . i .9) has been purified from Escherichia coli by a procedure involving autolysis, (NH4)2SO4 fractionation, adsorption on and elution from calcium phosphate gel, and column chromatography. The enzyme, which is about 650-fold purified over the initial cell-free extract, is homogeneous on ultracentrifugation (sedimentation coefficient 4.2 S) and on polyacrylamide-gel electrophoresis. Certain general properties of the enzyme and the effect of various metal ions on its activity have been determined. The enzyme is inhibited by N- ethylmaleimide and p- chloromercuribenzoate . Preliminary studies of the enzyme sulfhydryl groups have been carried out.

A convenient procedure for the determination of pyrrolidonecarboxylic acid and related compounds

Abstract A procedure is described for the quantitative determination of pyrrolidonecarboxylic acid by gas-liquid chromatography. The sample is treated with methanol containing hydrogen chloride; more than 97% of the pyrrolidonecarboxylic acid present is converted to the corresponding methyl ester under these conditions. Chromatography is carried out on a column of Chromosorb W coated with 0.2% by weight of each of three liquid phases (Versamid, neopentylglycol succinate, and Carbowax 1540) over the temperature range 130–150°. Samples containing 5 × 10−10 to 5 × 10−8 mole of pyrrolidonecarboxylic acid have been analyzed. The same system is also useful for the separate determination of pyrrolidone, α-methylpyrrolidonecarboxylic acid, and piperidonecarboxylic acid.

New Symbols for the Amino Acid Residues of Peptides and Proteins

A system of symbols for the amino acid residues of proteins and peptides is proposed. The symbols convey immediate meaning in chemical terms and therefore allow rapid recognition of the distribution and frequency of occurrence of the various functional groups. The system is readily adaptable to description of new amino acids and amino acid modifications.

Jesse Philip Greenstein 1902–1959

Publisher Summary This chapter focuses on Jesse Philip Greenstein. Jesse Philip Greenstein was born on June 20, 1902 in New York. His scientific interests developed early, while he attended public elementary and high schools in New York, and while he worked in the Food and Drug Laboratory of the New York City Department of Health. He was outstanding in scientific skill, learning, energy, and devotion to his work. He led an arduous life as an investigator, administrator, and writer. In the course of his career, he collaborated with more than 60 scientists. His work on the resolution of amino acids and emphasized the problem of the optical purity of amino acids. He inspired numerous young men, who came to work at the National Cancer Institute, with much of his own ardent enthusiasm for science. He was proud to be a servant of the United States Government, in a position of great responsibility, and his service went far beyond the allotted duties of his post. He was a loyal friend, whose wisdom and courage were a source of inspiration to his colleagues.

Observations on the Activation of Amino Acids and the Biosynthesis of Peptide Bonds

Publisher Summary This chapter discusses the activation of amino acids and the biosynthesis of peptide bonds. Formation of the peptide bond is initiated by a reaction involving the carboxyl group of one reactant, an enzyme, a metal ion (Mg ++ ), and adenosine 5’-tri-phosphate to form an enzyme-bound intermediate, which can react with a specific acceptor to yield another carboxyl-activated intermediate, or to form a peptide bond. The intermediate reacts with an acceptor in the absence of an external source of energy. In contrast to the synthesis of glutamine, the synthesis of phenylacetylglutamine and benzoylglycine involve participation of acyl adenylate intermediates. The formation of phenylacetyl glutamine requires both the presence of enzyme and of coenzyme A. Acyl adenylates are intermediates in the activation of fatty acids and in the synthesis of benzoylglycine and phenylacetylglutamine. When enzyme, ATP, Mg ++ , and amino acid are incubated with relatively high concentrations of hydroxylamine, the corresponding amino acyl hydroxamate is formed.