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pH‐dependent reversible inhibition of violaxanthin de‐epoxidase by pepstatin related to protonation‐induced structural change of the enzyme
Author(s) -
Kawano Mitsuko,
Kuwabara Tomohiko
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01991-8
Subject(s) - pepstatin , protonation , chemistry , violaxanthin , enzyme , enzyme inhibition , biophysics , biochemistry , biology , organic chemistry , zeaxanthin , ion , lutein , carotenoid , protease
The redox enzyme violaxanthin de‐epoxidase (VDE) was found to be sensitive to pepstatin, a specific inhibitor of aspartic protease. The inhibition was similar to that of aspartic protease in that it was reversible and accompanied by the protonation of the enzyme. Of the two peaks of VDE appearing on anion exchange chromatography, VDE‐I predominated at pH 7.2. On lowering the pH of the chromatography, VDE‐I decreased and VDE‐II increased. Furthermore, re‐chromatography of either peak yielded both peaks. These results suggest that VDE‐I and VDE‐II are interconvertible depending on pH, and thus, they represent the de‐protonated and protonated forms of the enzyme, respectively. Presumably the protonation‐induced structural change of the enzyme is responsible for the interaction with pepstatin, and also with substrate.