Investigations on Pantothenic Acid and Its Related Compounds XII. Biochemical Studies (7).* Dephospho-CoA Pyrophosphorylase and Dephospho-CoA Kinase as a Possible Bifunctional Enzyme Complex**

Abstract

1.Dephospho-CoA pyrophosphorylase [EC 2.7.7.3] and dephospho-CoA kinase [EC 2.7.1.24] were purified in the same fraction 248- and 266-fold, respectively, from rat liver 59,000 ×g supernatant. The ratio of specific activities of both enzymes remained constant throughout the purification procedures. 2.These two enzymes were not separated each other by CM-cellulose chromatography, DEAE-cellulose chromatography and Sephadex G-200gel filtration. 3. Inactivation by heat and stimulation by magnesium ion proceeded in parallel with these two enzyme activities. 4. In the presence of 0.01% of deoxycholate, the dephospho-CoA pyrophosphorylase reaction was stimulated, whereas dephospho-CoA kinase reaction was inhibited. Preincubation with 0.2% deoxycholate caused different changes in each of the two enzyme activities. 5. From the results obtained, a possible bifunctional enzyme complex system of these two enzymes was discussed. 6. The Michaelis constants of dephospho-CoA pyrophosphorylase for D-pantetheine-4′-phosphate and for ATP were 1.4×lO⁻⁴M and l.4×10⁻³M, respectively, and those of dephospho-CoA kinase for dephospho-CoA and for ATP were 1.2×lO⁻⁴M and 3.6×lO⁻⁴M, respectively.