- 作者: --
- 作者服務機構: Laboratoire de Chimie Organique Biologique, UMR 7123, Faculte de Chimie, Universite Louis Pasteur, Strasbourg, France
- 中文摘要: Evidence for a peripheral site that recognizes micelles where cholesterol is inserted, is presented for cholesterol oxidase from Brevibacterium sterolicum (CHOD). The Ω loop part of this site contains methionine residues. Their oxidation is reflected in a different selectivity to the micelles. When CHOD is oxidized with hydrogen peroxide, preferential introduction of two oxygen atoms by hydrogen peroxide to the enzyme is observed by the electrospray mass spectrometry. The modified enzyme does not oxidize cholesterol inserted in H-Triton X-100/sodium cholate mixed micelles. However, cholesterol solubilized in microemulsions, in biphasic media or inserted in hydroxypropyl-β-cyclodextrin is oxidized by the modified enzyme. This modified enzyme oxidizes pregn-5-en-3β-ol solubilized in mixed micelles, and soluble steroids, such as 3β-hydroxyandrost-5-en-17β-carboxylic acid or 3β-hydroxyandrost-5-en-17-one. So the modification does not occur at the active site, but at the peripheral site (methionine 81), abolishing the recognition of the micelles and thus inactivating the enzyme specifically towards cholesterol inserted in the micelles.
- 英文摘要: --
- 中文關鍵字: Cholesterol oxidase; Interfacial enzyme kinetics; Micelles; Steroids.
- 英文關鍵字: --