Open AccessKinetic Investigations with Inhibitors that Mimic the Postomolysis Intermediate in the Reactions of Coenzyme‐B 12 ‐Dependent Glycerol Dehydratase and Diol Dehydratase
Author(s) -
Poppe László,
Rétey János
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.00398.x
Subject(s) - chemistry , dehydratase , cofactor , stereochemistry , moiety , substrate (aquarium) , enzyme , non competitive inhibition , methylene , glycerol , coenzyme a , biochemistry , medicinal chemistry , reductase , biology , ecology
Kinetic investigations were performed on the coenzyme‐B 12 ‐dependent glycerol dehydratase and diol dehydratase reactions using 1,2‐propanediol as substrate and [ω‐(adenosin‐5′‐ O ‐yl)alkyl]cobalamins as mimics of the posthomolysis intermediate state of the coenzyme. All the coenzyme‐B 12 analogues with oligomethylene chains (C 3 –C 7 ) inserted between the central Co atom and the 5′ O of the adenosine moiety were competitive inhibitors with respect to coenzyme B 12 . The apparent inhibition constants ( K i ) of the shorter‐chain inhibitors, especially the C 5 inhibitor, were smaller for both enzymes than those of the longer‐chain (C 6 , C 7 ) compounds. These results are in agreement with the expected (0.6–0.9 nm) distance between the Co and 5′‐methylene paramagnetic centers in the posthomolysis intermediate state of coenzyme B 12 in these reactions.