ISSN:
1476-5535
Keywords:
d(−)-Lactate dehydrogenase
;
Membrane-bound protein
;
Sulfate-reducing bacterium
;
Desulfovibrio desulfuricans
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Summary A membrane-boundd(−)-lactate dehydrogenase (LDH), an important enzyme in carbon and energy metabolism in sulfate-reducing bacteria of the genusDesulfovibrio, was solubilized from the membrane fraction ofDesulfovibrio desulfuricans (ATCC 7757). The enzyme was purified 84-fold to a final specific activity of 525 nmol DCPIP-reduced/min/mg protein by ammonium sulfate precipitation, chloroform extraction, gel filtration with Sephadex G-150, and hydrophobic column chromatography withN-octylamine Sepharose 4B. The enzyme eluted off a Sephacryl S-300 column as a single peak with a molecular weight of 400 000±40 000 Da. Denaturing gel electrophoresis showed it to be composed of 5 protein bands. The oxidized and dithionite reduced spectra of LDH resembles the spectra ofc-type cytochromes found inDesulfovibrio species. The addition of lactate to LDH resulted in a partially reduced spectrum. The flavin/cytochromec/non-heme iron content per 400 000 Da LDH molecular weight was found to be 1∶1.6∶4.5. The LDH activity was specific ford(−)-lactate and had aK m ford(−)-lactate of 4.3×10−4 M. The pH optimum was between 6.5 and 8.5.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01576430
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