The NAD Kinases of <i>Saccharomyces cerevisiae</i>

Abstract

Subcellular fractions of a strain of Saccharomyces cerevisiae have been prepared by enzymic digestion of the cell walls, osmotic lysis of the protoplasts and sorbitol density gradient centrifugation of the lysate. The mitochondrial fraction has both NAD‐ and NADH‐phosphorylating enzymes, whilst the cytoplasm contains a single NAD‐specific kinase. These three enzymes differ in their kinetic properties and in their stability to heat and to an alkylating agent, 3‐(bromoacetyl) pyridine. The properties of the cytoplasmic NAD kinase resemble those of NAD kinase partially purified from autolysates of pressed bakers' yeast.