Labeling of the active site of α-chymotrypsin with N-nitroso-N-benzylacetamide and related-compounds

Min Li, David F. Roswell, Emil H. White

Research output: Contribution to journalArticlepeer-review


α-Chymotrypsin (CT) is slowly inhibited by N-nitroso-N-benzylacetamide (1) at 25ΰC. The 13C-NMR spectrum of the hydrolysate of 13C-enriched 1-inhibited CT shows five new signals at 52.33, 44.55, 43.72, 36.79, and 32.90 ppm resulting from alkylation of the side chains and also of amide linkages of the enzyme backbone by benzyl carbocations produced in the active site. The alkylation pattern is different from those observed in the inhibitions of CT with D-N-nitroso-N-[α-13C]-benzyl-N′-isobutyrylalaninamide (2a) and D-N-nitroso-N-[α-13C]-benzyl-N′-isobutyrylphenylalaninamide (2b) (White et al. JACS1990, 112, 1956 -1961). The chemical shift data suggest that the 52.33 ppm signal stems from N-benzylglycine, the 36.79 ppm signal from S-benzylcysteine, and the 32.90 ppm signal from 2-benzyltryptophan. A synthesis of the latter compound was developed.

Original languageEnglish (US)
Pages (from-to)907-913
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number2
StatePublished - Oct 29 1993

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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