Pentapeptides containing either L-methionine, L-proline, L-arginine, or L-lysine as central residue in the pattern glycylglycyl-X-glycylglycine have been studied at natural abundance by proton-decoupled 13C! nuclear magnetic resonance spectroscopy. Resonances were assigned in most cases by comparison with the free amino acids and by detailed observation of change in chemical shift with pH over ...

The presence of tetraphenylborate (TPB, 10 -3 M to 10 -4 M) in goldfish brain articulate preparations during a 5-15 min incubation with Y-~~P-ATP or y3f; P ATP results in marked stimulation of labeling of phosphatidate and a decrease in labeling of phosphatidyl inositol phosphate. Incorporation into phosphatidyl inositol diphosphate, a minor labeled phospholipid, is also depressed by TPB. We su...

The appropriate conditions for determining angiotensin-converting enzyme in human serum with use of 2-furanacryloyl-L-phenylalanylglycylglycine as substrate are described. The method, a modification of that reported by Holmquist et al. (Anal. Biochem. 95:540-548, 1979) for purified rabbit lung enzyme, is based on the blue shift of the absorption spectrum that occurs upon hydrolysis of the subst...

The reactions of a-chymotrypsinogen with carbon disulfide and with 0-methylisourea have been reported from this laboratory previously (1,2). The present report concerns the reaction of this protein with a new acylating agent, N-acetyl-nn-homocysteine thiolactone. The use of the thiolactone for the introduction of sulhydryl groups into proteins was fist suggested by Benesch and Benesch (3,4) who...

Suspensions of freshly isolated rat kidney cells were used to study glutathione biosynthesis and utilization for amino acid translocation. Incubation of cells isolated from diethylmaleate-perfused kidneys in the presence of glutamate, glycine, and cystine led to replenishment of cellular glutathione and to accumulation of glutathione disulfides in the medium. Cystine could be replaced by cystei...

For several years, data have been presented which suggested that the enzyme aldolase, from rabbit muscle, is composed of three subunits of identical, or nearly identical, size and structure (Drechsler et al 1959; Kowalsky -A, and Bayer, 1960; Schachman, 1960; Stellwagen and Schachman, 1962; Deal e al,,19653 Rutter et al 1965; and Winstead and Wold, 1964). More recent 3 data, however, indicate t...

A sensitive colorimetric procedure has been developed for the assay of angiotensin converting enzyme (EC 3.4.15.1) in serum. Serum (10 microL) is incubated for 30 min with hippuryl-glycyl-glycine as described earlier (Clin Chem 28: 1352-1355, 1982). After a Folin-Wu deproteinization, the liberated glycyl-glycine is derivatized with a borate-buffered (pH 9.3) trinitrobenzenesulfonate solution (6...