ISSN:
1432-072X
Keywords:
Desulfotomaculum
;
Sulfate reduction
;
Acetate oxidation
;
Acetyl-CoA
;
Carbon monoxide dehydrogenase
;
Tetrahydrofolates
;
Acetyl-CoA/carbon monoxide dehydrogenase pathway
;
Citric acid cycle
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Desulfotomaculum acetoxidans has been proposed to oxidize acetate to CO2 via an oxidative acetyl-CoA/carbon monoxide dehydrogenase pathway rather than via the citric acid cycle. We report here the presence of the enzyme activities required for the operation of the novel pathway. In cell extracts the following activities were found (values in brackets=specific activities and apparent K m; 1 U·mg-1=1 μmol·min-1·mg protein-1 at 37°C): Acetate kinase (6.3 U·mg-1; 2 mM acetate; 2.4 mM ATP); phosphate acetyltransferase (60 U·mg-1, 0.4 mM acetylphosphate; 0.1 mM CoA); carbon monoxide dehydrogenase (29 U·mg-1; 13% carbon monoxide; 1.3 mM methyl viologen); 5,10-methylenetetrahydrofolate reductase (3 U·mg-1, 0.06 mM CH3−FH4); methylenetetrahydrofolate dehydrogenase (3.6 U·mg-1, 0.9 mM NAD, 0.1 mM CH2=FH4); methenyltetrahydrofolate cyclohydrolase (0.3 U·mg-1); formyltetrahydrofolate synthetase (3 U·mg-1, 1.4 mM FH4, 0.4 mM ATP, 13 mM formate); and formate dehydrogenase (10 U·mg-1, 0.4 mM formate, 0.5 mM NAD). The specific activities are sufficient to account for the in vivo acetate oxidation rate of 0.26 U·mg-1.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00408310
Permalink
