Purification and properties of 3-hydroxybutyryl-coenzyme A dehydrogenase from Clostridium beijerinckii ("Clostridium butylicum") NRRL B59
Article Abstract:
The clostridial 3-hydroxybutyryl-coenzyme A dehydrogenase (3HBDH) catalyzes the reduction of acetoacetyl-coenzyme A by NAD(P)H, the committed step during butanol and butyrate synthesis. The 3HBDH of Clostridium beijerinckii NRRL B593 was purified through three gel filtration steps and was characterized. The results showed that the purified 3HBDH is a 213,000 Da enzyme containing subunits of 30,800 Da. The enzyme could use acetoacetyl-CoA, NADH and NADPH as substrates. However, it could also be inhibited by as low as 20 micromolar of acetoacetyl-CoA, which could be relieved by increasing the concentration of NADH.
Publication Name: Applied and Environmental Microbiology
Subject: Biological sciences
ISSN: 0099-2240
Year: 1992
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Redox cycling of iron supports growth and magnetite synthesis by Aquaspirillum magnetotacticum
Article Abstract:
Growth and magnetite synthesis of Aquaspirillum magnetotacticum is proportional to iron concentration when cultured under anaerobic conditions devoid of alternative electron acceptors. Under such conditions, A. magnetotacticum cells reduce ferric iron via the electron transport chain. Experiments suggest that ferric iron is used as a hydrogen sink, with iron reduction occuring before the cytochrome b to c electron transfer. Iron reoxidation appears necessary for magnetite synthesis since sequestration of reduced iron led to loss of magnetite from magnetosomes.
Publication Name: Applied and Environmental Microbiology
Subject: Biological sciences
ISSN: 0099-2240
Year: 1992
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