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.
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 beta-galactosidase) and up to 67% recovery following inhibition with compound 2.
Golan
R
R
Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
Zehavi
U
U
Naim
M
M
Patchornik
A
A
Smirnoff
P
P
Herchman
M
M
D000181:Acrylonitrile / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000494:pharmacology* / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000494:pharmacology* / Q000528:radiation effects; D005638:Fruit / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008027:Light; D009578:Nitrobenzenes / Q000138:chemical synthesis / Q000494:pharmacology* / Q000528:radiation effects; D010206:Papain / Q000037:antagonists & inhibitors* / Q000302:isolation & purification
C417196:1,1-dicyano-2-(4,5-dimethoxy-2-nitrophenyl)ethene; C099265:2-nitro-1-(4,5-dimethoxy-2-nitrophenyl)ethene; D004791:Enzyme Inhibitors; D009578:Nitrobenzenes; D010206:Papain; D000181:Acrylonitrile