Isolation of an iron-molybdenum cofactor from nitrogenase*
AUTOR(ES)
Shah, Vinod K.
RESUMO
A method for the isolation of an iron-molybdenum cofactor (FeMoCo) from component I of nitrogenase is described. This method is used to isolate FeMoCo from aerobic, anaerobic, facultative, and photosynthetic nitrogen-fixing organisms. The Fe/Mo ratio in the FeMoCo from Azotobacter vinelandii and Clostridium pasteurianum is 8:1. The FeMoCo contains six atoms of acid-labile sulfide per eight Fe atoms. Crystalline component I from A. vinelandii contains 2 Mo, 33 Fe, and 27 acid-labile sulfide atoms per molecular weight of 250,000. The specific activity of FeMoCo is 425 nmol of C2H4 formed/min per nmol of Mo. There is better than 98% reconstitution between FeMoCo and inactive component I in A. vinelandii mutant strain UW45. The FeMoCo yield from component I is about 90%. FeMoCo from nitrogenase component I of C. pasteurianum, Klebsiella pneumoniae, Bacillus polymyxa, and Rhodospirillum rubrum activates inactive component I in an extract from mutant strain UW45 and follows saturation kinetics. The FeMoCo in various nitrogen-fixing organisms seems to be very similar. Wild-type A. vinelandii derepressed for nitrogenase synthesis in tungsten-containing medium and K. pneumoniae mutant strain UN109 are also activated in vitro by FeMoCo.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=431518Documentos Relacionados
- Plausible structure of the iron-molybdenum cofactor of nitrogenase.
- Biosynthesis of iron-molybdenum cofactor in the absence of nitrogenase.
- Metal and sulfur composition of iron-molybdenum cofactor of nitrogenase.
- In vitro synthesis of the iron-molybdenum cofactor of nitrogenase.
- Selenol binds to iron in nitrogenase iron-molybdenum cofactor: an extended x-ray absorption fine structure study.
