Pyrroloquinoline quinone (PQQ) has been claimed to be a component of glutamate decarboxylase 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 decarboxylase 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.
A chromophore in glutamate decarboxylase has been wrongly identified as PQQ / DE BIASE, Daniela; Maras, Bruno; John, Ra. - In: FEBS LETTERS. - ISSN 0014-5793. - STAMPA. - 278:(1991), pp. 120-122.
A chromophore in glutamate decarboxylase has been wrongly identified as PQQ
DE BIASE, Daniela;MARAS, Bruno;
1991
Abstract
Pyrroloquinoline quinone (PQQ) has been claimed to be a component of glutamate decarboxylase 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 decarboxylase 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
