Halobacterium ferredoxin-dependent oxidoreductases
Two key enzymatic steps in central metabolism are the conversion of pyruvate to acetyl-CoA and of alpha-ketoglutarate to succinyl-CoA. These enzymatic reactions result in oxidative decarboxylation of the substrate. In Halobacterium salinarum and many archaea these are catalyzed by ferredoxin-dependent protein complexes while in Escherichia coli and most bacteria and eukaryotes these are catalyzed by lipoamide-dependent enzyme complexes.
Physiological role:
Pyruvate dehydrogenase converts pyruvate to acetyl-CoA which is then completely oxidyzed through the citric acid cycle.
Reaction catalyzed:
pyruvate + HSCoA + fdx(ox) --> acetyl-CoA + CO2 + fdx(red)
Protein complex:
Pyruvate dehydrogenase is a heterotetramer.
Subunits:
alpha chain: porA OE2623R PIR:S22396
beta chain: porB OE2622R PIR:S22397
Genes:
the genes porA-porB form a transcription unit.
Coenzymes and redox partners:
ferredoxin fdx OE4217R
coenzyme A
thiamine pyrophosphate
Experimental data:
The protein was purified and its catalytic properties were determined.
The molecular weight of the protein complex and its subunits as well as the amino acid composition was determined.
Protein sequencing of the N-terminus and of internal peptides was achieved.
The presence of the coenzyme thiamine pyrophosphate and the absence of the coenzyme lipoamide was verified.
References:
Physiological role:
Reaction catalyzed:
Subunits:
Genes:
Coenzymes and redox partners:
Experimental data:
rss
Top
Print