Zur chemischen Zusammensetzung der Zellwand der Streptokokken - II. Die Aminosäuresequenz des Mureins von Str. lactis und cremoris

Cell walls of Str. lactis 211b and 212b and Str. cremoris 71, 316a and 331a contain no teichoic acid and teichuronic acid, but polysaccharide and murein. The polysaccharide consists of rhamnose, glucose, glucosamin and galactose. The murein of Str. lactis 211b, 212b and Str. cremoris 71 contains MurNAc: GlcNAc: Glu: Lys: Asp: Ala at a molar ratio of approximately 1: 1: 1: 1: 1: 2. L-alanin and D-alanin occuroat equimolar amounts. Two moles of ammonia were found per mole of glutamic acid. This indicates that glutamic acid and aspartic acid are present as amides. In the hydrolysate of the dinitrophenylated cell walls ε-DNP-aspartic acid and ε-DNP-lysine were found. Hydrolysis of the cell walls yielded ε-(aminosuccinyl)-lysine in addition to amino sugars and amino acids. The occurrence of this compound suggests that aspartic acid is bound to the ε-amino group of lysine. The murein of Str. cremoris 316a and 331a contains additionally threonine, instead of aspartic acid and moreover one mole of L-alanine more than the murein of the above mentioned organisms. MurNAc, GlcNAc, Glu, Lys, Thr, Ala occur at a ratio of approximately 1: 1: 1: 1: 1: 3. The ratio L-alanine/D-alanine is 2: 1. One mole of ammonia was found per mole of glutamic acid. This indicates that glutamic acid is present as an amide. Dinitrophenylation and hydrolysis of the cell walls yielded small amounts of DNP-alanine and ε-DNP-lysine. Hydrazinolysis yielded free alanine. The splitting of trichloroacetic acid-extracted cell walls by lysozyme yielded complex muropeptides with the same amino acid ratio as the murein. Inhibition by vancomycin led to the accumulation of the same UDP-muramyl-pentapeptide as in Str. thermophilus.