13C-n.m.r. of the cyanylated apoflavodoxin and flavodoxin from Clostridium pasteurianum

The thiol group of the flavodoxin from Clostridium pasteurianum has been cyanylated in a single step using [cyanato-13C]2-nitro-5-thiocyanatobenzoic acid. This chemical modification increases the dissociation constant of the apoflavodoxin-FMN complex 10-fold from 0.33 +/- 0.15 nM to 2.9 +/- 1.3 nM....

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Bibliographic Details
Published in:Biochemical journal 1993-08, Vol.294 (1), p.215-218
Main Authors: DOHERTY, G. M, MAYHEW, S. G, MALTHOUSE, J. P. G
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Apoproteins - chemistry
Biological and medical sciences
Carbon Isotopes
Clostridium - chemistry
Coenzymes, vitamins
Cyanides - chemistry
Flavodoxin - chemistry
Fundamental and applied biological sciences. Psychology
Magnetic Resonance Spectroscopy
Other biological molecules
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Summary:The thiol group of the flavodoxin from Clostridium pasteurianum has been cyanylated in a single step using [cyanato-13C]2-nitro-5-thiocyanatobenzoic acid. This chemical modification increases the dissociation constant of the apoflavodoxin-FMN complex 10-fold from 0.33 +/- 0.15 nM to 2.9 +/- 1.3 nM. The thiocyanate carbons of the cyanylated cysteine residue of apoflavodoxin and flavodoxin had chemical shift values of 114.7 and 112.3 p.p.m. respectively. From these chemical shifts we conclude that the binding of FMN by the cyanylated apoflavodoxin causes a decrease in the polarity and/or hydrogen bonding capacity of the environment of the thiocyanate group. We compare these results with those obtained from similar studies on the cyanylated apoflavodoxin and flavodoxin from Megasphaera elsdenii and we discuss how FMN binding and cyanylation perturb the structures of apoflavodoxins from Megasphaera elsdenii and Clostridium pasteurianum.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2940215