The phosphate recognition site of Escherichia coli maltodextrin phosphorylase

FEBS Letters

Schinzel, R.¹  Drueckes, P.¹ 

[1] Physiologisch-Chemisches Institut, Biozentrum, Am Hubland, D-8700 Würzburg, Germany

关键词: Structure—function;    Site-directed mutagenesis;    Steady-state kinetics;    Pyridoxal-P;    pyridoxal 5′-phosphate;    glucose-1-P;    α D-glucopyranose-1-phosphate;   

DOI  :  10.1016/0014-5793(91)80956-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The role of two positively charged amino acid residues located at the active site of Escherichia coli maltodextrin phosphorylase was investigated by site-directed mutagenesis, Substitution of Lys⁵³⁹ by an arginine caused a 600-fold reduction, substitution of Arg⁵³⁴ by a glutamine caused an even larger 7000-fold reduction of the catalytic rate while substrate binding remained essentially unaffected. Since the Arg⁵³⁴→Gln exchange reduces the catalytic rate near to inactivity and even the conservative Lys⁵³⁴→Arg exchange caused a marked decrease of activity, the central functional role of both positively charged residues in phosphorylase catalysis anticipated by the crystallographic analysis of the corresponding amino acid residues Arg⁵⁶⁹ and Lys⁵⁷⁴ in the catalytic site of phosphorylase b was confirmed.

【 授权许可】

Unknown