Effects of acrylamide on creatine kinase from rabbit muscle

The mechanism of inhibition of creatine kinase (CK) by acrylamide (Acr) has been examined (in vitro). Within the concentration range of 0 to 1 M, Acr markedly inhibited CK and depleted the protein thiols. Both inactivation an d thiol depletion were time- and Acr concentration-dependent. Addition of d ithiothreitol (DTT) did not reactivate CK inactivated by Acr. However, CK w ith 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) pre-blocked thiols can be r eactivated by DTT after incubation with Acr. The transition-state analogue also had a significant protective effect on CK against Acr inhibition. We c onclude that thiol alkylation is a critical event in inactivation of CK by Acr. Furthermore, Acr binding to CK changed its surface charge, which may b e the same effect for the toxicity of Aer towards other proteins. (C) 2001 Elsevier Science Ltd. All rights reserved.