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A chromophore in glutamate decar☐ylase has been wrongly identified as PQQ
Author(s) -
Daniela De Biase,
Bruno Maras,
Robert A. John
Publication year - 1991
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 - 10.1016/0014-5793(91)80097-m
Subject(s) - pyrroloquinoline quinone , chemistry , pyridoxal phosphate , enzyme , pyridoxal , biochemistry , chromophore , glutamate receptor , cofactor , organic chemistry , receptor
Pyrroloquinoline quinone (PQQ) has been claimed to be a component of glutamate decar☐ylase from Escherichia coli on the basis of a frequently used procedure in which the protein is extracted with hexanol. We demonstrate that if pyridoxal phosphate (PLP) is not added during the preparation, the apoenzyme prepared from glutamate decar☐ylase contains no chromophore absorbing above 280 nm. Full enzyme activity and the original holoenzyme spectrum are restored by the addition of PLP alone, A 340 nm‐absorbing band, similar to that which prompted analysis for PQQ, is produced by exposure of the enzyme to solutions of PLP.