Conversion of the active-site cysteine residue of papain into a dehydro-serine, a serine and a glycine residue.
Photolysis of papain which had been inhibited with 2-bromo-2',4'-dimethoxyacetophenone regenerated papain, but also formed [deltaSer25]-papain (i.e. papain in which the active-site cysteine residue 25 was replaced by dehydroserine) via the intermediate dehydrocysteine analogue, [deltaCys25]-papain. Reduction with sodium borohydride gave [Ser25]papain. Both [Ser25]papain and [deltaSer25]-papain had binding properties similar to those of papain, but were devoid of enzymic activity. Their fluorescence properties were also investigated. Incubation of [deltaSer25]papain at pH 9.0 gave [Gly25]papain.
D000098:Acetophenones; D001665:Binding Sites; D003545:Cysteine; D005998:Glycine; D006863:Hydrogen-Ion Concentration; D010206:Papain / Q000528:radiation effects*; D010782:Photolysis; D012694:Serine / Q000031:analogs & derivatives*; D013050:Spectrometry, Fluorescence
D000098:Acetophenones; D012694:Serine; C016345:dehydroserine; D010206:Papain; D003545:Cysteine; D005998:Glycine