Cellular properties of the coenzyme A-synthesizing protein complex of Bakers' yeast

A multienzyme complex contained in Bakers' yeast which synthesizes CoA has been named the coenzyme-A-synthesizing protein complex (CoA-SPC). The CoA-SPC has been shown to be insoluble in the crude Bakers' yeast cell lysate. Only after solubilization has this multienzyme complex been shown to catalyze the synthesis of CoA utilizing the substrates ATP, D-pantothenic acid and L-cysteine. A low molecular weight component of the 105,000 x g supernatant fraction of the yeast cell lysate, referred to as t-Factor, and chloride ion are responsible for the solubilization of CoA-SPC. Purification of t-Factor has been accomplished utilizing dialysis, ultrafiltration, paper chromatography and permeation chromatography. Purified t-Factor has been shown to be stable to heat at 80° for 24 h and resistant to hydrolysis by trypsin and protease. Although t-Factor has not yet been identified, several properties of this low molecular weight component are known. Mixing t-Factor and chloride ion with washed pellet material, obtained by centrifugation of the yeast lysate at 105,000 x g for 1 h, gradually solubilizes CoA-SPC. Mechanical stirring appears to facilitate this process. Consequently, the recovery of CoA-SPC in a relatively purified form, essentially free of proteolytic enzymes, can be accomplished by this technique.