Inactivation of purine nucleoside phosphorylase by modification of arginine residues. |
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Authors: | F Jordan A Wu |
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Affiliation: | Carl A. Olson Chemistry Laboratories, Rutgers University, Newark, New Jersey 07102 USA |
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Abstract: | Treatment of purine nucleoside phosphorylase (EC 2.4.2.1), from either calf spleen or human erythrocytes, with 2,3-butanedione in borate buffer or with phenylglyoxal in Tris buffer markedly decreased the enzyme activity. At pH 8.0 in 60 min, 95% of the catalytic activity was destroyed upon treatment with 33 mM phenylglyoxal and 62% of the activity was lost with 33 mm 2,3-butanedione. Inorganic phosphate, ribose-1-phosphate, arsenate, and inosine when added prior to chemical modification all afforded protection from inactivation. No apparent decrease in enzyme catalytic activity was observed upon treatment with maleic anhydride, a lysine-specific reagent. Inactivation of electrophoretically homogeneous calf-spleen purine nucleoside phosphorylase by butanedione was accompanied by loss of arginine residues and of no other amino acid residues. A statistical analysis of the inactivation data vis-à-vis the fraction of arginines modified suggested that one essential arginine residue was being modified. |
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Keywords: | To whom correspondence should be addressed. |
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