European Journal of Biochemistry 1978-03-01

Conversion of the active-site cysteine residue of papain into a dehydro-serine, a serine and a glycine residue.

P I Clark, G Lowe

Index: Eur. J. Biochem. 84(1) , 293-9, (1978)

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Abstract

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.