Chemical modification of the functional arginine residues of carbon monoxide dehydrogenase from Clostridium thermoaceticum

Carbon monoxide dehydrogenase (CODH) is the key enzyme of autotrophic growth with CO or CO2 and H2 by the acetyl-CoA pathway. The enzyme from Clostridium thermoaceticum catalyzes the formation of acetyl-CoA from the methyl, carbonyl, and CoA groups and has separate binding sites for these moieties....

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Bibliographic Details
Published in:Biochemistry (Easton) 1989-08, Vol.28 (17), p.7112-7116
Main Authors: Shanmugasundaram, T, Kumar, Ganesh K, Shenoy, Bhami C, Wood, Harland G
Format: Article
Language:English
Subjects:
Aldehyde Oxidoreductases - antagonists & inhibitors
Aldehyde Oxidoreductases - metabolism
Aldehydes - pharmacology
Analytical, structural and metabolic biochemistry
Arginine
Biological and medical sciences
carbon monoxide dehydrogenase
Circular Dichroism
Clostridium - enzymology
Coenzyme A - pharmacology
Enzymes and enzyme inhibitors
Fundamental and applied biological sciences. Psychology
Kinetics
Multienzyme Complexes
Oxidoreductases
Phenylglyoxal - pharmacology
Protein Conformation
Spectrometry, Fluorescence
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Summary:Carbon monoxide dehydrogenase (CODH) is the key enzyme of autotrophic growth with CO or CO2 and H2 by the acetyl-CoA pathway. The enzyme from Clostridium thermoaceticum catalyzes the formation of acetyl-CoA from the methyl, carbonyl, and CoA groups and has separate binding sites for these moieties. In this study, we have determined the role of arginine residues in binding of CoA by CODH. Phenylglyoxal, an arginine-specific reagent, inactivated CODH, and CoA afforded about 80-85% protection against this inactivation. The other ligands, such as the carbonyl and the methyl groups, gave no protection. By circular dichroism, it was shown that the loss of activity is not due to extensive structural changes in CODH. Earlier, we showed that tryptophan residues are located at the CoA binding site of CODH [Shanmugasundaram, T., Kumar, G. K., & Wood, H. G. (1988) Biochemistry 27, 6499-6503]. A comparison of the fluorescence spectra of the native and phenylglyoxal-modified enzymes indicates that the reactive arginine residues appear to be located close to fluorescing tryptophans. Fluorescence spectral studies with CoA analogues or its components showed that CoA interacts with the tryptophan(s) of CODH through its adenine moiety. In addition, evidence is presented that the arginines interact with the pyrophosphate moiety of CoA.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00443a049