Tryptophan 110, a residue involved in the toxic activity but not in the enzymatic activity of notexin

Pascale MOLLIER, Serge CHWETZOFF, Françoise BOUET, Alan L. HARVEY, André MÉNEZ

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

We prepared two derivatives of notexin, a phospholipase A2 from Notechis scutatus scutatus venom, by modifying the protein with 2‐nitrophenylsulfenylchloride, a tryptophan‐specific reagent. One derivative was modified at both tryptophans 20 and 110 whereas the other was modified at tryptophan 20. Evidence based on circular dichroic analysis and antigenicity towards a notexin‐specific monoclonal antibody indicated that derivatization at both tryptophans did not affect the tertiary structure of notexin. Concomitant modification of tryptophans 20 and 110 induced a marked decrease in the capacity of notexin to kill mice and to block neuromuscular transmission in the chick biventer cervicis preparation, whereas selective modification at tryptophan 20 had no effect on the lethal properties of notexin. This implies that the decrease in the lethal properties of notexin after derivatization was due to modification at tryptophan 110. However, the diderivatized notexin retained full enzymatic activity, implying that neither tryptophan 20 and tryptophan 110 are involved in the catalytic function of the molecule. We conclude that notexin harbours two functional sites. One of them corresponds to the enzymatic site, whereas the other, which includes tryptophan 110, provides specific toxic characteristics to notexin. By reference to previous crystallographic studies, the relative spatial positions of elements involved in toxicity and the catalytic site, we propose a possible orientation of notexin with respect to its putative membrane‐bound target.

Original languageEnglish
Pages (from-to)263-270
Number of pages8
JournalEuropean Journal of Biochemistry
Volume185
Issue number2
DOIs
Publication statusPublished - 1 Jan 1989

Keywords

  • notexin
  • phospholipase a2
  • snake venom
  • tryptophan
  • animal cell
  • amino acid sequence
  • antibodies, monoclonal
  • neurotoxins

Fingerprint Dive into the research topics of 'Tryptophan 110, a residue involved in the toxic activity but not in the enzymatic activity of notexin'. Together they form a unique fingerprint.

  • Cite this