Studies of arteriosclerosis in Japanese and American men. I. Comparison of fatty acid composition of adipose tissue

The proportions of fatty acids in lipids of subcutaneous adipose tissue was compared in closely age-matched, urban men from two populations with a great difference in mortality from arteriosclerosis, namely in 50 Americans and 56 Japanese aged 15-65 yr who had died suddenly and unexpectedly. Specimens from both groups were analyzed side by side for fatty acids by gas-liquid chromatography. Compared with Japanese, Americans had significantly (P<0.01) higher proportions of lauric (+ 0.2%), myristic (+ 0.4%), palmitic (+ 1.4%), stearic (+ 2.2%), and oleic (+ 5.3%) and lesser of palmitoleic (- 1.8%), linoleic (-6.3%), and linolenic (-0.4%) acids. Japanese had higher proportions of longer chain polyunsaturated fatty acids. The distributions of fatty acids for the groups at ages 35-44 yr had significant differences. With age, Americans showed significant increases of palmitic and oleic acids and decreases of lauric, myristic, stearic, and linoleic acids; Japanese showed no correlations of proportions of fatty acids with age. The significant correlations between per cent standard body weight and fatty acids in Americans were positive for palmitic and negative for lauric and stearic acids, and in Japanese, negative for myristic acid. The patterns of interacid correlations were dissimilar for the groups. These patterns may be stable characteristics of these groups providing further insight into their fatty acid metabolism. The relationships with the fatty acid compositions of the American and Japanese diets are discussed.

Proteinase enzyme system of lactic streptococci. 3. Substrate specificity of Streptococcus lactis intracellular proteinase

The substrate specificity of an intracellular proteinase from Streptococcus lactis was investigated in an effort to understand the role of the enzyme in the cell. Peptides in which the N-terminal residue was glycine were not hydrolyzed by the enzyme (exceptions were glycyl-alanine, glycyl-aspartic acid, and glycyl-asparagine), but the peptide was hydrolyzed if the N-terminal residue was alanine. The enzyme also showed activity toward peptides containing aspartic acid or asparagine. Hydrolysis of only the peptide bonds of alanyl, aspartyl, or asparaginyl residues was confirmed by the action of the enzyme on oxidized bovine ribonuclease A- and B- chain insulin. The N-terminal residues of the peptide fragments liberated were identified. The enzyme attacked both substrates only at alanyl, aspartyl, and asparaginyl residues, releasing these as free amino acids. In addition to alanine, aspartic acid, and asparagine, certain other amino acids were liberated from ribonuclease A, but these were accounted for by the relation of their position to alanine, aspartic acid, and asparagine residues.