| Autor: |
Lassmann, Günter, Damerau, Werner, Sklenar, Gisela, Schwarz, Dieter, Frohne, Marlies, Ludewig, Manfred, Hanson, Horst |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry; Jun75 Part 1, Vol. 54 Issue 2, p453-458, 6p |
| Abstrakt: |
1. Leucine aminopeptidase (EC 3.4.11.1 ) from bovine eye lens was spin-labeled at the most reactive thiol groups with 2,2,6,6-tetramethyl-4-12-iodoacetamidol-piperidine-l-oxyl. 2. Electron spin resonance spectra show two spectral parts corresponding to two local conformational states in the environment of bound label. One state (A) exhibits a strong immobilizing effect on the mobility of the bound label whereas the other one (B) Immobilizes weakly. Independently on the degree of labeling a ratio of A : B ∼ 4:1 was estimated. In B a hydrophobic environment of label was observed. 3. Treatment of leucine aminopeptidase by 6.2 M urea leads to the following structural changes. a) An additional weakly immobilizing conformational state (B') with reduced hydrophobic interactions and increased mobility representing an unfolded conformational state appears. B' shows a time-dependent increase of its extent at the expense of B and A' (haft conversion time about 0.5 h). The extent of this conformational change is larger, if the enzyme is additionally complexed with Mn2+. b) Mn2+ complexed with the protein is partly released producing hydrated Mn2+. c) After withdrawal of urea the observed conformational changes in leucine aminopeptidase are fully reversible, giving the initial ratio of A : B ∼ 4:1 even after long incubation. 4. 6.2 M urea is not able to destroy the strongly immobilizing conformational state A completely. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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