Premium
Characterization of inter‐domain electron transfer in Ncb5or, a redox enzyme involved in fatty acid desaturation
Author(s) -
Deng Bin,
Parthasarathy Sudharsan,
Xu Ming,
Wang WenFang,
Benson David R,
Zhu Hao
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.lb225
Subject(s) - cytochrome b5 , electron transfer , fatty acid , chemistry , cytochrome , enzyme , biochemistry , photochemistry
Microsomal cytochrome b5 (b5) and cytochrome b5 reductase (b5R) are redox proteins that donate electrons to stearoyl‐CoA desaturase (SCD) in fatty acid desaturation. N ADH c ytochrome b5 o xido r eductase (Ncb5or) contains b5 and b5R domains, and a linkage domain similar to the CS ( C HORD‐ S GT1) family members. Our recent studies show that Ncb5or functions as an alternative electron donor for SCD. Ncb5or knockout mice display lipoatrophy and diabetes as a result of impaired fatty acid desaturation. In this study, we aim to characterize the properties of individual human Ncb5or domains, the inter‐domain electron transfer and the role of CS domain. Recombinant b5, b5R, and CS+b5R domains were generated from a bacterial system. Native gel electrophoresis revealed that b5 is stable under heat treatment, but b5R and CS+b5R are not. Inter‐domain electron transfer can be reconstituted by mixing b5 with b5R or CS+b5R under excess NADH, indicating a non‐essential role of CS in electron transfer. The percentage of heme reduction increases with decreasing salt concentrations, suggesting an electrostatic interaction. In the same buffer, b5R reduces more heme than CS+b5R. Both b5R and CS+b5R alone can reduce cytochrome c with the same rate. The addition of b5 increases the rate, more with b5R than CS+b5R. We conclude that electrons can flow from both b5 and b5R to cytochrome c but only the b5‐b5R interaction is specific. Supported by NIH.