SH Form Research Articles

Amino acid interactions in strict anaerobes (Cl. Sporogenes)

1. 1. Amino acid hydrogen donators compete with each other, and amino acid hydrogen acceptors also compete with each other, in anaerobic amino acid interactions in Cl. sporogenes. 2. 2. The competition of these substances is due to the fact that diphosphopyridine nucleotide acts as a common hydrogen carrier between the amino acid hydrogen donators and the amino acid hydrogen acceptors. 3. 3. Molecular hydrogen absorption by amino acid hydrogen acceptors is greatly suppressed by the presence of amino acid hydrogen donators in Cl. sporogenes. 4. 4. Ferricyanide acts as a hydrogen acceptor, competing with amino acid hydrogen acceptors, in Cl. sporogenes. 5. 5. Pyruvate is established as an intermediate in anaerobic alanine-proline interaction in Cl. sporogenes, by its diversion to lactate in presence of lactic dehydrogenase of animal tissues. 6. 6. Anaerobic amino acid interactions, as well as pyruvate-amino acid interaction, give rise to sulfanilamide acetylation in extracts of Cl. sporogenes, when an extract of pigeon liver is added. 7. 7. Aerobic alanine oxidation by Cl. sporogenes is greatly accelerated by the presence of pyruvate or α-ketoglutarate, which acts in this way by non-enzymic interaction with hydrogen peroxide (formed during alanine oxidation). 8. 8. Exposure of Cl. sporogenes to air, oxygen or hydrogen peroxide, exert highly toxic effects on amino acid oxidations or anaerobic interactions. These may be prevented by the presence of pyruvate or of thiol compounds. 9. 9. The toxic effects of air or oxygen or dilute hydrogen peroxide on the enzymatic mechanisms of Cl. sporogenes may be reversed by subsequent additions of thiol compounds. It is suggested that the amino acid activating enzymes are thiol systems, which are converted to the inert-S-S-form by oxygen or dilute hydrogen peroxide. This inert form may be converted to the active -SH form by treatment with thiol compounds. 10. 10. The amino acid activating enzymes, particularly the amino acid reductases, are highly sensitive to organic arsenoxides which exert large inhibitory effects on amino acid interactions in Cl. sporogenes.

Some Properties of a Hemolysin Produced by Group A β-Hemolytic Streptococci

Summary Some properties of a hemolysin produced by group A hemolytic streptococci of the beta type on a meat infusion broth and on an essentially protein free medium are described. A partial purification of the hemolysin has been achieved. The hemolysin is reversibly inactivated by oxidizing agents such as oxygen, hydrogen peroxide, iodine and potassium ferricyanide. Such oxidized hemolysin can be reactivated by a series of thiol compounds, by potassium cyanide and to some extent by leuco methyl viologen, but not by all reducing agents. The hemolysin is also inactivated by cuprous oxide, phenyl mercuric chloride, phenyl mercuric nitrate, alloxan, maleic acid, iodoacetic acid, iodoacetamide and cholesterol. The inactivation caused by each of these, except the last, can be at least in large part reversed by thiol compounds. Many of the results with activating and inactivating reagents suggest that the hemolysin contains and —SH⇄—S—S— oxidation-reduction system and that this system must be in the —SH form in active hemolysin. Some difficulties in accepting this view as the entire explanation are pointed out. The partially purified fractions show all the properties of protein solutions. A typical preparation contained 15.3 per cent nitrogen, 1.9 per cent sulfur and 0.1 per cent phosphorus. Part of the sulfur is present in the form of —SH groups, part as sulfate sulfur and part in undetermined form. The partially purified preparations of hemolysin are neutralized by various antisera, as is the untreated supernatant broth of cultures of hemolytic streptococci. This neutralization is independent of the state of purification or reduction of the hemolysin and is not accompanied by any precipitation, in the available range of concentrations of the reactants. We gratefully acknowledge the supplies of sera received from the Lederle and Squibb Laboratories, the Laboratories of Sharp and Dohme, and the National Drug Company, as well as the strains of bacteria and the streptococcal products received from Dr. David Lackman.