Send to

Choose Destination
See comment in PubMed Commons below
Proc Natl Acad Sci U S A. 1991 Apr 15;88(8):3272-6.

Resolution of component proteins in an enzyme complex from Methanosarcina thermophila catalyzing the synthesis or cleavage of acetyl-CoA.

Author information

Department of Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.


An enzyme complex was isolated from acetate-grown Methanosarcina thermophila that oxidized CO and catalyzed the synthesis or cleavage of acetyl-CoA. The complex consisted of five subunits (alpha1beta1gamma1delta1epsilon1) of 89, 71, 60, 58, and 19 kDa. The complex contained nickel, iron, acid-labile sulfide, and cobalt in a corrinoid cofactor. Two components were resolved by anion-exchange chromatography of the complex in the presence of dodecyltrimethylammonium bromide and Triton X-100: a 200-kDa nickel/iron-sulfur protein with the 89- and 19-kDa (alpha2epsilonx) subunits and a 100-kDa corrinoid/iron-sulfur protein with the 60- and 58-kDa subunits (gamma1delta1). The nickel/iron-sulfur component contained 0.21 Ni, 2.7 Zn, 7.7 Fe, and 13.2 acid-labile sulfide (per alpha1epsilon1). The corrinoid/iron-sulfur component contained 0.7 Co, 0.7 factor III [Coalpha-[alpha-(5-hydroxybenzimidazolyl)]-Cobeta-cyanocobamide], 3.0 Fe, and 2.9 acid-labile sulfide (gamma1delta1). Both components contained iron-sulfur centers. The nickel/iron-sulfur component oxidized CO and reduced methyl viologen or a ferredoxin isolated from M. thermophila. The nickel/iron-sulfur component also oxidized CO and transferred electrons to the corrinoid/iron-sulfur component, reducing the iron-sulfur and Co centers. UV-visible spectroscopy indicated that the reduced corrinoid/iron-sulfur component could be methylated with CH3I. The results suggest that the enzyme complex from M. thermophila contained at least two enzyme components, each with a specific function. The properties of the component enzymes support a mechanism proposed for acetyl-CoA synthesis (or cleavage) by the enzyme complex.

PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center