Purification and characterization of a highly thermostable, oxygen-resistant, respiratory [NiFe]-hydrogenase from a marine, aerobic hydrogen-oxidizing bacterium Hydrogenovibrio marinus
✍ Scribed by Ki-Seok Yoon; Keiichi Fukuda; Kiyoshi Fujisawa; Hirofumi Nishihara
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 391 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0360-3199
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✦ Synopsis
The membrane-bound [NiFe]-hydrogenase from Hydrogenovibrio marinus (HmMBH) was purified homogeneously under anaerobic conditions. Its molecular weight was estimated as 110 kDa, consisting of a heterodimeric structure of 66 kDa and 37 kDa subunits. The purified enzyme exhibited high activity in a wide temperature range: 185 U/mg at 30 C and 615 U/mg at 85 C (the optimum temperature). The K m and k cat /K m values for H 2 were, respectively, 12 mM and 8.58 Â 10 7 M À1 s À1 . The optimum reaction pH was 7.8, but its stability was particularly high at pH 4.0e7.0. Results show that HmMBH was remarkably thermostable and oxygen-resistant: its half-life was 75 h at 80 C under H 2 , and more than 72 h at 4 C under air. The air-oxidized HmMBH for 72 h showed only weak EPR signals of NieB, suggesting a structural feature in which the active center is not easily oxidized.