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dc.contributor.authorCoolbear, C.
dc.contributor.authorEames, Chris W.
dc.contributor.authorCasey, Y.
dc.contributor.authorDaniel, Roy M.
dc.contributor.authorMorgan, Hugh W.
dc.identifier.citationPatchett, M.L., Daniel, R.M. & Morgan, H.W. (1991). Characterisation of arginase from the extreme thermophile ‘Bacillus caldovelox’. Journal of Applied Microbiology, 71(3), 252-264.en_NZ
dc.description.abstractA thermostable arginase (l-arginine amidinohydrolase, EC was purified from the extreme thermophile ‘Bacillus caldovelox’ (DSM 411) by a procedure including DEAE-Sepharose chromatography, and gel filtration, anion exchange and hydrophobic-interaction fast-protein liquid chromatography, with substantial retention of the metal ion cofactor. The purified enzyme is a hexamer with a subunit Mr of 31000 ± 2000 and contains ≥1 Mn atom per subunit. Maximum activation on incubation with Mn²⁺ is 29%. Activity is optimal at pH 9 and at 60°C the Km for arginine is 3.4 mM and Ki(ornithine) is 0.55 mM. Incubation in 0.1 M Mops/NaOH buffer (pH 7) causes rapid inactivation at 60°C (t1/2(half life) = 4.5 min) and individually 0.1 mM Mn²⁺ or 1 mg/ml BSA (bovine serum albumin) increase the t1/2 of arginase activity 4-fold, but combined they produce > 1000-fold increase and a t1/2 = 105 min at 95°C. Aspartic acid and other species that bind Mn²⁺ can replace BSA, and it is suggested that arginase can be activated by free Mn²⁺. A strong chelating agent causes inactivation without subunit dissociation, but arginase dissociates rapidly at pH 2.5. Reassociation occurs at pH 9 and is unusual in that it does not require Mn²⁺.en_NZ
dc.subjectL-Arginine amidinohydrolaseen_NZ
dc.subjectenzyme inactivationen_NZ
dc.subjectmanganese enzymeen_NZ
dc.subjectthermostable enzymeen_NZ
dc.subjectBacillus caldoveloxen_NZ
dc.titleScreening of strains identified as extremely thermophilic bacilli for extracellular proteolytic activity and general properties of the proteinases from two of the strainsen_NZ
dc.typeJournal Articleen_NZ

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