Lactic dehydrogenase and cytochrome b2 of baker's yeast. The amino acid composition of the crystalline enzyme

Abstract

Crystalline cytochrome b2 was hydrolyzed with 5 [image]-hydrochloric acid at 105 [degree] for 20 hours and the liberated amino acids were separated by paper chromatography according to Dent (1947) and Boissonnas (1950). Most of the commonly occurring amino acids, except methionine, were detected. The amino acids in hydrolysates obtained after 20 and 7 hours at 110[degree] with constant-boiling HC1 solution were separated on a column of Dowex-50 according to Moore and Stein (1951) and estimated by the color developed with ninhydrin. Methionine was not detected. Comparison of the amino acid composition of cytochrome b2, yeast cytochrome c, yeast alcohol dehydrogenase and pig-heart diaphorase shows considerable similarity between these several proteins.