Content Of Sulfur-containing Amino Acids Research Articles

SOME CHARACTERISTICS OF STREPTOCOCCAL NICOTINAMIDE ADENINE DINUCLEOTIDASE AND STREPTOLYSIN O.

Pentz, E. Irene (Northwestern University School of Medicine, Chicago, Ill.), Eva Kot, and J. J. Ferretti. Some characteristics of streptococcal nicotinamide adenine dinucleotidase and streptolysin O. J. Bacteriol. 88:497-508. 1964.-Nicotinamide adenine dinucleotidase produced by Streptococcus pyogenes strain C203U, grown in Todd-Hewitt broth (Difco), was recovered from diethylaminoethyl-cellulose columns free from streptolysin O. It contained a trace of deoxyribonuclease. The elution peak of nicotinamide adenine dinucleotidase was fairly symmetrical; when it was treated with dinitrofluorobenzene (DNFB) and chromatogrammed on paper in three different solvent systems, only one yellow spot was obtained. Examination of the enzyme in an ultracentrifuge presented no moving boundary. The pore size of two different widths of Visking casing was estimated by dialyzing proteins or peptides of known molecular weight and testing the dialysate for their appearance. The casing which allowed a molecule of 2,500 molecular weight to pass, but not one of 3,000 molecular weight, retained the nicotinamide adenine dinucleotidase. A fragment having no nicotinamide adenine dinucleotidase activity did pass through this casing, however, but was retained by the second casing which retained molecules weighing 2,500. Amino acid analyses of three different nicotinamide adenine dinucleotidase preparations were remarkably similar, and were characterized by a high content of proline and glycine and a very low content of sulfur-containing amino acids. Examination by treatment with DNFB followed by hydrolysis for the presence of N-terminal amino acids ruled out all amino acids, with the possible exception of arginine. The combined evidence suggests that its molecular weight is between 2,500 and 20,000. Some data are presented to illustrate the irreversible instability of streptolysin O; amino acid analyses for three separate preparations of high activity indicate a very low content of sulfur-containing amino acids.

AMINO ACID COMPOSITION OF VARIOUS FORMS OF BOVINE AND HUMAN ERYTHROCYTE CARBONIC ANHYDRASE.

1. 1. Amino acid analyses and determinations of elementary composition of various forms of bovine and human erythrocyte carbonic anhydrase (carbonate hydro-lyase, EC 4.2.1.1) have been carried out. A technique for the calculation of molecular weights from amino acid composition is described. 2. 2. A feature common to all of the forms of the enzyme studied is their low content of sulfur-containing amino acids which excludes the occurence of disulfide bridges in the molecules. The bovine enzyme contains no cysteine and it is thus possible to exclude a sulfhydryl group as a ligand in the binding of the zinc ion to the protein. 3. 3. Great differences in amino acid composition are found between forms from the different species as well as between different forms of the human enzyme. However, some of the electrophoretically separable forms of the enzyme show identical amino acid composition within the experimental errors. The possible biosynthetic relations between the forms of the human enzyme are discussed.

SOME PROPERTIES OF APOFERRITIN ISOLATED FROM GUINEA PIG LIVER

Apoferritin isolated from livers of guinea pigs and characterized by a s°w,20of 17.7 and a pI of 4.8 (in acetate buffer Γ/2 0.1) was hydrolyzed with 5.7 N HCl for 22 and 44 hours and its amino acid composition determined. The protein appears rich in dicarboxylic acids and in leucine. The content of sulphur-containing amino acids is fairly small.

SOME PROPERTIES OF APOFERRITIN ISOLATED FROM GUINEA PIG LIVER

Apoferritin isolated from livers of guinea pigs and characterized by a s°w,20of 17.7 and a pI of 4.8 (in acetate buffer Γ/2 0.1) was hydrolyzed with 5.7 N HCl for 22 and 44 hours and its amino acid composition determined. The protein appears rich in dicarboxylic acids and in leucine. The content of sulphur-containing amino acids is fairly small.