Ligand-Induced Conformational Changes near the Active Site Regulating Enzyme Activity of Momorcharins from Seeds of Bitter Gourd

Chie Matsunaga, Yuuki Okada, Etsuko Nishimoto

Research output: Contribution to journalArticle

Abstract

It is reasonable to consider that Type I-ribosomal inactivation proteins (RIP) retain some specific affinity to harmful pathogens to complete the role as a bio-defense relating protein. In the present studies, it was shown that two Type I-RIPs, α- and β-momorcharins, maintained the abilities to bind with N-acetylglucosamine (NAG) to change the conformation around the active sites and to regulate their N-glycosidase activities. By the binding of NAG, the freedom of internal motion of Trp192 in α-momorcharin was increased 1.5 times near the active site and, on the other hand, the corresponding motion of Trp190 was limited 50% in β-momorcharin. The results in the fluorescence resonance excitation energy transfer experiments demonstrated that Trp-190 of β-momorcharin was kept away from Tyr-70 but Trp192 contrarily approached closer to the nearest neighboring Tyr residue consisting of the active center of α-momorcharin by the binding with NAG. These conformational changes near the active site close correlated with promotion and/or suppression of the N-glucosidase activities of β- and α-momorcharins.

Original languageEnglish
Pages (from-to)231-240
Number of pages10
JournalJournal of Fluorescence
Volume29
Issue number1
DOIs
Publication statusPublished - Jan 15 2019

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Clinical Psychology
  • Social Sciences (miscellaneous)
  • Sociology and Political Science
  • Spectroscopy
  • Clinical Biochemistry
  • Law

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