Study on the mechanism of action of adenosylcobalamin-dependent glycerol dehydratase from Aerobacter aerogenes. I. Role of structural components of adenosylcobalamin the formation of the active site of glycerol dehydratase.
A new method of partial chemical synthesis of adenosylcobalamin (Co alpha-[alpha-5,6-diemethylbenzimidazolyl)]-Co beta-adenosylcobamide, AdoCbl) analogs has been developed. A series of derivatives of AdoCbl modified in the nucleoside and nucleotide ligands and corrin macrocycle have been obtained. The interaction of AdoCl analogs with glycerol dehydratase (EC 4.2.1.30) from Aerobacter aerogenes has been investigated. It has been shown that the nucleoside ligand of AdoCbl provides no essential contribution to the binding of apoenzyme but the preservation of the exact structure of the 1-N and 2-C positions of adenine appears essential for the catalysis. The coordination bond between the Co and nucleotide ligand of AdoCl does not play a decisive role in glycerol dehydratase activity. To form the active site of the glycerol dehydrates, the nucleotide in the AdoCbl structure is essential since nucleotide elimination results in a 100-fold increase of Ki for the corresponding analog. In the binding of AdoCbl with apoenzyme, the main role belongs to the corrin macrocycle, in which the e-propionamide group is significant for binding with apoenzyme, but presumably not essential for catalysis.
D000227:Adenine Nucleotides; D001051:Apoenzymes / Q000378:metabolism; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D002942:Circular Dichroism; D003038:Cobamides / Q000378:metabolism; D004754:Enterobacter / Q000201:enzymology*; D004755:Enterobacteriaceae / Q000201:enzymology*; D005990:Glycerol; D006836:Hydro-Lyases / Q000378:metabolism; D007700:Kinetics; D013329:Structure-Activity Relationship
D000227:Adenine Nucleotides; D001051:Apoenzymes; D003038:Cobamides; D006836:Hydro-Lyases; C020671:glycerol dehydratase; D005990:Glycerol