Article

Functional proton transfer pathways in the heme-copper oxidase superfamily.

Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
Biochimica et Biophysica Acta (impact factor: 4.66). 10/2011; 1817(4):537-44. DOI:10.1016/j.bbabio.2011.10.007 pp.537-44
Source: PubMed

ABSTRACT Heme-copper oxidases (HCuOs) terminate the respiratory chain in mitochondria and most bacteria. They are transmembrane proteins that catalyse the reduction of oxygen and use the liberated free energy to maintain a proton-motive force across the membrane. The HCuO superfamily has been divided into the oxygen-reducing A-, B- and C-type oxidases as well as the bacterial NO reductases (NOR), catalysing the reduction of NO in the denitrification process. Proton transfer to the catalytic site in the mitochondrial-like A family occurs through two well-defined pathways termed the D- and K-pathways. The B, C, and NOR families differ in the pathways as well as the mechanisms for proton transfer to the active site and across the membrane. Recent structural and functional investigations, focussing on proton transfer in the B, C and NOR families will be discussed in this review.

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Keywords

active site
 
C-type oxidases
 
catalytic site
 
D-
 
denitrification process
 
HCuO superfamily
 
HCuOs
 
K-pathways
 
liberated free energy
 
oxygen-reducing A-
 
pathways
 
Proton transfer
 
proton-motive force
 
Recent structural
 
well-defined pathways