Studies in tissue metabolism

STEPHENSON [1928] and Bernheim [1928] obtained lactic dehydrogenase of B. coli and of baker's yeast respectively in solution.Both preparations oxiidised lactic acid to pyruvic acid and did not appear to have any coenzyme.Bernheim dialysed his preparations for 7 hours without destroying the activity.One of us [Boyland, E., 1933, 2] found that zymin from baker's yeast could be washed with large quantities of water without loss of lactic dehydrogenase activity [see also Harden and Macfarlane, 1931].Within the last few years the lactic dehydrogenase of mammalian heart-muscle has been investigated by Szent-Gyorgyi [1925], who has shown that this enzyme requires a coenzyme, the nature of which he has attempted to determine [Banga et al. 1932; Banga and Szent-Gy6rgyi, 1933].The coenzyme is not adenylpyrophosphate [Banga and Szent-Gyorgyi, 1932] or vitamin B1 [Boyland, E., 1933, 1; Birch and Mann, 1934], nor is it identical with glucose dehydrogenase coenzyme of liver (Harrison, personal communication, and observations with a sample kindly supplied by Dr Harrison).Holmberg [1934] found that cozymase or Fiske's adenylpyrophosphate could act as coenzyme for lactate oxidation by heart-muscle in the presence of methylene blue.Preparation of heart-muscle dehydrogenase in solution.