A highly efficient procedure for purifying the ribosome-activating proteins α- and β-momorcharins from Momordica charantia seeds, N-terminal sequence comparison and establishment of their N-glycosidase activity

W. P. Fong*, Y. T. Poon, T. M. Wong, J. W.Y. Mock, T. B. Ng, Ricky N S WONG, Q. Z. Yao, H. W. Yeung

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)

Abstract

A new purification scheme, involving two successive ion exchange chromatographic steps on DEAE-cellulose and Mono-S FPLC, was developed for the isolation of the ribosome-inactivating proteins, α- and β-momorcharins, from the Chinese herb Kuquazi (seeds of Momordica charantia). This simple and rapid procedure yielded 3.1 and 1.7 mg of α- and β-momorcharins, respectively, from 2.5 g of decorticated seeds in only two days. The N-terminal amino acid sequence of β-momorcharin was found to be DVNFDLSTATAKTYTKFIED. It differed from that of α-momorcharin (DVSFRLSGADPRSYGMFIKD) in 10 out of the 20 positions investigated. Like other ribosome-inactivating proteins, the purified momorcharins showed specific N-glycosidase activity at nanomolar concentrations, when rRNA from rabbit reticulocyte lysate was used as substrate. The N-glycosidase activity of both momorcharins was optimal at pH 7, not inhibited by K+ and not appreciably affected by NH4+. The activity of α-momorcharin was not drastically altered by Mn2+ but (1-10 mM) Mn2+ inhibited the activity of β-momorcharin by about 40%.

Original languageEnglish
Pages (from-to)901-909
Number of pages9
JournalLife Sciences
Volume59
Issue number11
DOIs
Publication statusPublished - 9 Aug 1996

Scopus Subject Areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

User-Defined Keywords

  • Momordica charantia
  • N-glycosidase
  • Purification
  • Ribosome-inactivating proteins
  • RNA

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