Interaction of radical anion probes with glucoamylase I from Aspergillus niger.
Copper, P L Power, D M Richards, J T Davies, J Vernon
Copper, P L
Power, D M
Richards, J T
Davies, J Vernon
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Abstract
The radical anions (SCN)2.- and Br2.- produced during a pulse radiolysis of the respective potassium salts have been used to study the tryptophan residues of the glucoenzyme, glucoamylase I (EC 3.2.1.3.). At neutral pH, Br2.- reacted with the tryptophan residues of glucoamylase I as expected from previous studies of proteins and free amino acids. However, (SCN)2.- at neutral and high pH was surprisingly unreactive towards the native enzyme. Reaction did occur, however, between (SCN)2.- and glucoamylase from which one-third of the covalently bound carbohydrate had been removed, producing a tryptophyl radical. Reaction also occured between (SCN)2.- and glucoamylase I inactivated by treatment with sodium dodecyl sulphate, but the tryptophan residues were not involved. It is concluded from the results that two 'types' of tryptophan residues are found in glucoamylase I; both are attacked by Br2.- but only one type is attacked by (SCN)2.-.
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1978-11
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Article
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Interaction of radical anion probes with glucoamylase I from Aspergillus niger. 1978, 34 (5):431-8 Int. J. Radiat. Biol. Relat. Stud. Phys. Chem. Med.