Beef-heart malic dehydrogenases. III. Comparative studies of some properties of M-malic dehydrogenase and S-malic dehydrogenase.

摘要: Abstract The two malic dehydrogenases from beef heart, identified as being supernatant and mitochondrial in origin, have been compared further with regard to kinetic behavior additional striking differences observed. With respect sulfhydryl groups of dehydrogenase supernantant the following established. First, has twice number half-cystine residues contained (12 opposed 6). Secondly, all undenatured can be titrated p -mercuribenzoate, although reaction occurs slowly, while only half even presence excess reagent. Finally, titration -mercuribenzoate results loss enzymic activity after addition three equivalents reagent, whereas no supernatant-malic its titrated. Significant amino acid composition exist between dehydrogenase. latter enzyme contains more lysine, arginine, tyrosine, methionine, aspartic tryptophan than does former. On other hand, phenylalanine, glycine, proline threonine.