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Stability and sulfur‐reduction activity in non‐aqueous phase liquids of the hydrogenase from the hyperthermophile Pyrococcus furiosus
Author(s) -
Kim Chulhwan,
Woodward Charlene A.,
Kaufman Eric N.,
Adams Michael W. W.
Publication year - 1999
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19991005)65:1<108::aid-bit13>3.0.co;2-r
Subject(s) - pyrococcus furiosus , hydrogenase , sulfur , chemistry , aqueous solution , phase (matter) , reduction (mathematics) , organic chemistry , enzyme , biochemistry , archaea , gene , geometry , mathematics
Hydrogenase from the hyperthermophilic archaeon, Pyrococcus furiosus, catalyzes the reversible activation of H 2 gas and the reduction of elemental sulfur (S°) at 90°C and above. The pure enzyme, modified with polyethylene glycol (PEG), was soluble (> 5 mg/mL) in toluene and benzene with t 1/2 values of more than 6 h at 25°C. At 100°C the PEG‐modified enzyme was less stable in aqueous solution (t 1/2 ∼ 10 min) than the native (unmodified) enzyme (t 1/2 ∼ 1 h), but they exhibited comparable H 2 evolution, H 2 oxidation, and S° reduction activities at 80°C. The H 2 evolution activity of the modified enzyme was twice that of the unmodified enzyme at 25°C. The PEG‐modified enzyme did not catalyze S° reduction (at 80°C) in pure toluene unless H 2 O was added. The mechanism by which hydrogenase produces H 2 S appears to involve H 2 O as the proton source and H 2 as the electron source. The inability of the modified hydrogenase to catalyze S° reduction in a homogeneous non‐aqueous phase complicates potential applications of this enzyme. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 65:108–113, 1999.