Premium
Stereochemistry of the Methyl Group in ( R )‐3‐Methylitaconate Derived by Rearrangement of 2‐Methylideneglutarate Catalysed by a Coenzyme B 12 ‐Dependent Mutase
Author(s) -
Ciceri Daniele,
Pierik Antonio J.,
Hartrampf Günter,
Bröker Gerd,
Speranza Giovanna,
Buckel Wolfgang,
Cornforth Sir John,
Golding Bernard T.
Publication year - 2000
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20000906)83:9<2550::aid-hlca2550>3.0.co;2-c
Subject(s) - chemistry , mutase , methyl group , adenosylcobalamin , stereochemistry , methyl radical , radical , substrate (aquarium) , cofactor , methylene , corrin , medicinal chemistry , group (periodic table) , photochemistry , enzyme , organic chemistry , ring (chemistry) , oceanography , geology
2‐Methylideneglutarate mutase is an adenosylcobalamin (coenzyme B 12 )‐dependent enzyme that catalyses the equilibration of 2‐methylideneglutarate with ( R )‐3‐methylitaconate. This reaction is believed to occur via protein‐bound free radicals derived from substrate and product. The stereochemistry of the formation of the methyl group of 3‐methylitaconate has been probed using a `chiral methyl group'. The methyl group in 3‐([ 2 H 1 , 3 H]methyl)itaconate derived from either ( R )‐ or ( S )‐2‐methylidene[3‐ 2 H 1 ,3‐ 3 H 1 ]glutarate was a 50 : 50 mixture of ( R )‐ and ( S )‐forms. It is concluded that the barrier to rotation about the C−C bond between the methylene radical centre and adjacent C‐atom in the product‐related radical [ . CH 2 CH( − O 2 CC=CH 2 )CO 2 − ] is relatively low, and that the interaction of the radical with cob(II)alamin is minimal. Hence, cob(II)alamin is a spectator of the molecular rearrangement of the substrate radical to product radical.