Separation of the Condensing Enzyme of Aspergillus niger from Acetyl Coenzyme A Deacylase and Citridesmolase and the Effect of Magnesium Ion on the Purified Fraction

Abstract

THE condensing enzyme found in various tissues has been generally found to require magnesium for its activity. However, an exception was reported by Ramakrishnan and Martin¹, who found that the condensing enzyme of Aspergillus niger does not require magnesium and is, on the contrary, inhibited by it. Horecker and Mehler² suspected that the presence of citridesmolase as a contaminant might be responsible for this inhibition. Further, the presence of acetyl coenzyme A deacylase in cell-free extracts of A. niger has been recently detected in this laboratory and the enzyme purified³. It will be noted that this enzyme also needs magnesium for optimal activity and that the presence of this enzyme as a contaminant in the condensing enzyme is likely to cause its inhibition by magnesium. I have therefore reinvestigated the problem of the magnesium requirements of the condensing enzyme with reference to the presence of contaminants.