Mechanistic Study of the Stereoselective Hydroxylation of [2-2 H1 ,3-2 H1 ]Butanes Catalyzed by Cytochrome P450 BM3 Variants.
Chemistry
; 23(11): 2571-2582, 2017 Feb 21.
Article
em En
| MEDLINE
| ID: mdl-27798822
ABSTRACT
Engineered bacterial cytochromeâ
P450s are noted for their ability in the oxidation of inert small alkanes. Cytochromeâ
P450 BM3 L188P A328F (BM3â
PF) and A74E L188P A328F (BM3â
EPF) variants are able to efficiently oxidize n-butane to 2-butanol. Esterification of the 2-butanol derived from this reaction mediated by the aforementioned two mutants gives diastereomeric excesses (de) of -56±1 and -52±1 %, respectively, with the preference for the oxidation occurring at the C-HS bond. When tailored (2R,3R)- and (2S,3S)-[2-2 H1 ,3-2 H1 ]butane probes are employed as substrates for both variants, the obtained de values from (2R,3R)-[2-2 H1 ,3-2 H1 ]butane are -93 and -92 % for BM3â
PF and EPF, respectively; whereas the obtained de values from (2S,3S)-[2-2 H1 ,3-2 H1 ]butane are 52 and 56 % in the BM3â
PF and EPF systems, respectively. The kinetic isotope effects (KIEs) for the oxidation of (2R,3R)-[2-2 H1 ,3-2 H1 ]butane are 7.3 and 7.8 in BM3â
PF and EPF, respectively; whereas KIEs for (2S,3S)-[2-2 H1 ,3-2 H1 ]butanes are 18 and 25 in BM3â
PF and EPF, respectively. The discrepancy in KIEs obtained from the two substrates supports the two-state reactivity (TSR) that is proposed for alkane oxidation in cytochromeâ
P450 systems. Moreover, for the first time, experimental evidence for tunneling in the oxidation mediated by P450 is given through the oxidation of the C-HR bond in (2S,3S)-[2-2 H1 ,3-2 H1 ]butane.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Butanos
/
Sistema Enzimático do Citocromo P-450
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article