Structural Insights into the Very Low Activity of the Homocoenzyme B12 Adenosylmethylcobalamin in Coenzyme B12 -Dependent Diol Dehydratase and Ethanolamine Ammonia-Lyase.
Chemistry
; 28(65): e202202196, 2022 Nov 21.
Article
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| MEDLINE
| ID: mdl-35974426
ABSTRACT
The X-ray structures of coenzyme B12 (AdoCbl)-dependent eliminating isomerases complexed with adenosylmethylcobalamin (AdoMeCbl) have been determined. As judged from geometries, the Co-C bond in diol dehydratase (DD) is not activated even in the presence of substrate. In ethanolamine ammonia-lyase (EAL), the bond is elongated in the absence of substrate; in the presence of substrate, the complex likely exists in both pre- and post-homolysis states. The impacts of incorporating an extra CH2 group are different in the two enzymes the DD active site is flexible, and AdoMeCbl binding causes large conformational changes that make DD unable to adopt the catalytic state, whereas the EAL active site is rigid, and AdoMeCbl binding does not induce significant conformational changes. Such flexibility and rigidity of the active sites might reflect the tightness of adenine binding. The structures provide good insights into the basis of the very low activity of AdoMeCbl in these enzymes.
Palabras clave
Texto completo:
1
Base de datos:
MEDLINE
Asunto principal:
Propanodiol Deshidratasa
/
Etanolamina Amoníaco-Liasa
Idioma:
En
Revista:
Chemistry
Asunto de la revista:
QUIMICA
Año:
2022
Tipo del documento:
Article
País de afiliación:
Japón