Inhibition of Papaya latex papain by photosensitive inhibitors. 1-(4,5-dimethoxy-2-nitrophenyl)-2-nitroethene and 1,1-dicyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene |
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Authors: | Golan R Zehavi U Naim M Patchornik A Smirnoff P Herchman M |
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Affiliation: | (1) Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 76100, Israel;(2) Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 76100, Israel;(3) Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, 76100, Israel |
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Abstract: | 1-(4,5-Dimethoxy-2-nitrophenyl)-2-nitroethene (1) was shown to be an irreversible inhibitor of papain (EC 3.4.22.2), causing a complete inhibition (120 min preincubation, pH 8.0), assuming that it attached to Cys-25 at the active site of the enzyme (while a short preincubation time caused activation). Only partial inhibition of papain was achieved, however, with 1,1-dicyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene (2), a compound synthesized in this work, which is also an irreversible inhibitor of papain. Since both compounds 1 and 2, and in each case of the inhibited enzyme, were 2-nitrobenzyl derivatives, they and the modified enzyme were expected to be photosensitive. Indeed, irradiation of the inhibited enzyme in the presence of mercaptoethanol resulted in a full recovery of the enzyme activity following inactivation with compound 1 (similar to our previous finding with -galactosidase) and up to 67% recovery following inhibition with compound 2. |
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Keywords: | Papain photoreversible inhibitor light-sensitive protecting group 1-(4,5-dimethoxy-2-nitrophenyl)-2-nitroethene 1,1-dicyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene |
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