Kazuo Asaoka

The complete amino acid sequence of bullfrog (Rana catesbeiana) parvalbumin pI4.97

The primary structure of the parvalbumin (pI4.97) from bullfrog, Rana catesbeiana, skeletal muscle has been determined. It is composed of 110 amino acid residues and a free amino terminus, and has a molecular mass of 11919. The amino add sequences which are thought to be functionally important sites are also conserved in the bullfrog parvalbumin. The calculated phylogenic tree indicates that this parvalbumin belongs to the α group of parvalbumins. The mutation rate of parvalbumin was fairly rapid in frogs compared to mammals. The subdivergence of frogs is also discussed.

GLUTATHIONE CONJUGATION OF NITRO COMPOUNDS BY MONKEY GLUTATHIONE S-TRANSFERASES

The distribution in Japanese monkey tissues of glutathione S-transferase activity toward some aromatic nitro compounds was examined by measuring the release of the nitro group as nitrite ion. The activity was especially high in liver, kidney and small intestine when compounds such as 4-nitroquinoline N-oxide, 5-nitrofurfural diacetal and o-dinitrobenzene were used as substrates. The nitrite-releasing activity of the major enzyme purified from rhesus monkey liver was also tested on fifty-two nitro compounds including nineteen nitrofuran derivatives. Among the thirty-three nitro compounds other than the nitrofuran derivatives tested as substrates, the purified enzyme showed activity only toward o-dinitrobenzene, 4-nitroquinoline N-oxide, 3,4-dinitrobenzoic acid, p-dinitrobenzene, 2,5-dinitrobenzoic acid, 2,5-dinitrophenol, tetra-chloronitrobenzene and 2,4-dinitrobenzoic acid. The crude supernatant fraction of rhesus monkey liver showed activity in substrate specificity roughly similar to that of the purified enzyme. On the other hand, among at least ten carcinogenic 2-substituted 5-nitrofran derivatives tested, 4,6-diamino-2-(5-nitro-2-furyl)-s-triazine, 5-nitro-2-furaldehyde semicarbazone, N-[[3-(5-nitro-2-furyl)-1,2,4-oxadiazol-5-yl]methyl] acetamide, and N-[5-(5-nitro-2-furyl)-1-3,4-thiadiazol-2-yl)acetamide were shown to be enzymatically conjugated with reduced glutathione. Among the other nine 2-substituted 5-nitrofuran derivatives tested, six compounds could be the substrates of the enzyme, and 5-nitrofurfural and 5-nitrofurfural diacetal were especially good substrates. There was, however, little apparent correlation between their carcinogenicity and susceptibility to glutathione S-transferase. The bulky substituents at position 2 appeared to decrease the susceptibility of these nitrofuran derivatives to the enzyme. Both Vmax and Km values of the purified enzyme varied greatly among the substrates, and the optimum pH fell between 7.5 and 9.0 in most cases.

Purification and characterization of the parvalbumin from monkey skeletal muscle.

1. A high affinity Ca2+ binding and low mol. wt protein, parvalbumin, was purified from monkey skeletal muscle. 2. As compared with other animals, only one component and a lower content of monkey parvalbumin were found. 3. This may suggest that both the component and the content of parvalbumin decreases with biological evolution. 4. The parvalbumin was found to have a mol. wt of 11,400, a pI of 5.1, a high aspartic acid and lysine content, maximum absorption at around 260 nm, a blocked amino-terminal, an immunological distinction, 2 mol Ca2+ binding/mol, and a conformational change by Ca2+ binding. 5. Parvalbumin was shown to have alpha type properties.