Journal of Biosciences

, Volume 4, Issue 3, pp 287–294 | Cite as

Studies on the properties of the variants of gamma-glutamyl transpeptidase in human urine

  • K. Rambabu
  • T. N. Pattabiraman


Both the high molecular weight and the low molecular weight variants of urinary Y-glutamyl transpeptidase, displayed transpeptidase (pH optimum 8.6) and autotrans-peptidase (pH optimum 9.4) activities. Iodoacetamide inhibited the transpeptidase activity more efficiently than the autotranspeptidase activity with respect to both variants of Y-glutamyl transpeptidase. The high molecular weight form utilized L-glutamine as a better acceptor than L-cystine during the transpeptidation reaction whereas the reverse was the case with the low molecular weight variant. While phenylmethylsulphonyl fluoride-treated enzymes retained full activitiesper se, addition of maleic acid to the modified enzyme was found to inhibit the catalytic activities indicating a maleic acid-induced conformational change of the modified enzyme.


Urinary Y-glutamyl transpeptidase variants autotranspeptidation chemical modification 

Abbreviations used


trinitrobenzene sulphonic acid


phenylmethylsulphonyl fluoride


dithiobis 2-nitrobenzoic acid














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Copyright information

© Indian Academy of Sciences 1982

Authors and Affiliations

  • K. Rambabu
    • 1
  • T. N. Pattabiraman
    • 1
  1. 1.Department of BiochemistryKasturba Medical CollegeManipal

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