3'-DEPHOSPHO-COENZYME AN ANALOGS WITH A P HOSPHODIESTER BOND AS SUBSTRATES OF S-ACETYLATION REACTION CATALYZED BY ACETYL-COA SYNTHETASE FROM RABBIT MYOCARDIUM

A number of earlier unknown 3'-dephospho-CoASH analogues with the pyro phosphate fragment replaced by an ester or phosphodiester bond were sy nthesized and tested in S-acetylation reaction, catalyzed by acetyl-Co A synthetase (EC 6.2.1.1) from rabbit myocardium. 3'-Dephospho-CoASH a nalogues with a phosphodiester bond, e. g. (Ia), had a lower affinity and diminished kinetic parameters than 3'-dephospho-CoASH (K(m) = 1 an d 0.2 mM, respectively). The adenine substitution in (Ia) by guanine o r hypoxanthine (but not cytosine) residue resulted in a loss of substr ate properties. 3'-Dephospho-CoASH with an ester bond were not capable of accepting acetate under conditions used and only slightly inhibite d the enzymic activity.