Nonaromatic products from anoxic conversion of benzoyl-CoA with benzoyl-CoA reductase and cyclohexa-1,5-diene-1-carbonyl-CoA hydratase.
The enzymes benzoyl-CoA reductase and cyclohex-1, 5-diene-1-carbonyl-CoA hydratase catalyzing the first steps of benzoyl-CoA conversion under anoxic conditions were purified from the denitrifying bacterium, Thauera aromatica. Reaction products obtained with [ring-(13)C(6)]benzoyl-CoA and [ring-(14)C]benzoyl-CoA as substrates were analyzed by high pressure liquid chromatography and by NMR spectroscopy. The main product obtained with titanium(III) citrate or with reduced [8Fe-8S]-ferredoxin from T. aromatica as electron donors was identified as cyclohexa-1, 5-diene-1-carbonyl-CoA. The cyclic diene was converted into 6-hydroxycyclohex-1-ene-1-carbonyl-CoA by the hydratase. Assay mixtures containing reductase, hydratase, and sodium dithionite or a mixture of sulfite and titanium(III) citrate as reducing agent afforded cyclohex-2-ene-1-carbonyl-CoA and 6-hydroxycylohex-2-ene-1-carbonyl-CoA. The potential required for the first electron transfer to the model compound S-ethyl-thiobenzoate yielding a radical anion was determined by cyclic voltammetry as -1.9 V versus a standard hydrogen electrode. The energetics of enzymatic ring reduction of benzoyl-CoA are discussed.
Boll
M
M
Mikrobiologie, Institut für Biologie II, Universität Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany.
Laempe
D
D
Eisenreich
W
W
Bacher
A
A
Mittelberger
T
T
Heinze
J
J
Fuchs
G
G
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000693:Anaerobiosis; D002851:Chromatography, High Pressure Liquid; D006836:Hydro-Lyases / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D020628:Thauera / Q000378:metabolism
D000214:Acyl Coenzyme A; C037817:benzoyl-coenzyme A; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C109030:benzoyl-coenzyme A reductase (dearomatizing); D006836:Hydro-Lyases; C114397:cyclohexa-1,5-diene-1-carboxyl-CoA hydratase