Lactic dehydrogenase and cytochrome b2 of baker's yeast. Enzymic and chemical properties of the crystalline enzyme

作者：Cyril A. Appleby, R. K. Morton · 发表于：Biochemical Journal · 年份：1959 · DOI：10.1042/bj0730539 · 被引用次数：111 · 研究领域：Enzyme Production and Characterization、Microbial Metabolites in Food Biotechnology、Enzyme Structure and Function

Bach, Dixon & Zerfas (1946) found that cytochrome b2 (Bach, Dixon & Keilin, 1942) was an essential part of the dehydrogenase system of baker's yeast which catalysed the reduction of methylene blue by lactate.Appleby & Morton (1954) reported that purified crystalline lactic dehydrogenase of yeast was a chromoprotein having both protohaem and riboflavin phosphate as essential prosthetic groups and was identical with cytochrome b2.The procedure for purification and crystallization of the enzyme has been published (Appleby & Morton, 1959).Some enzymic and chemical pro- perties of the crystalline material are described here.This work was described at the meeting of the Australian and New Zealand Association for the Advancement of Science in Melbourne, 1955, and some preliminary accounts have been published (Appleby & Morton, 1954;Morton, 1955). MATERIALS Crystalline yeast lactic dehydrogenase (cytochrome b2).This was prepared as described by Appleby & Morton (1959).Unless otherwise stated, the material was recrystallized at least once, and sometimes twice, from a solution of the combined first crystals from a number of preparations.Hydroxy acids.DL-u-Hydroxy-n-butyric acid (Bios Laboratories Ltd.), DL-fl-hydroxy-n-butyric acid (British Drug Houses Ltd.) and a-hydroxy-iso-butyric acid (East- man Organic Chemicals Ltd.), at approx.molar concen- tration, were hydrolysed at 1000 for 1 hr.and then adjusted to about pH 7 0 with 5N-NaOH and diluted to 0-5M con- centration.Glycollic acid ...