Photoaffinity labelling of methyltransferase enzymes with S-adenosylmethionine: Effects of methyl acceptor substrates

Jeffrey H. Hurst, Melvin Billingsley, Walter Lovenberg

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Radioactivity from 3H-[methyl]-S-adenosyl-L-methionine (AdoMet) was covalently bound to protein-O-carboxylmethyltransferase and phenylethanolamine N-methyltransferase following 10-15 min irradiation by short-wave ultraviolet light. This photoaffinity binding of 3H-[methyl]-AdoMet was blocked by S-adenosylhomocysteine and sinefungin, but was not affected by 5 mM dithiothreitol. The binding was also inhibited by including methyl acceptors such as calmodulin (protein-O-carboxylmethyltransferase) or phenylethanolamine (phenylethanolamine N-methyltransferase) in the photoaffinity incubation. Staphlococcus V8 protease digests of 3H-[methyl]-AdoMet/enzyme complexes revealed that the primary structure around the AdoMet binding site is different in these two enzymes. Thus, protein-O-carboxylmethyltransferase, a large molecule methyltransferase, can covalently bind 3H-[methyl]-AdoMet in a manner similar to that of phenylethanolamine-N-methyltransferase.

Original languageEnglish (US)
Pages (from-to)499-508
Number of pages10
JournalBiochemical and Biophysical Research Communications
Volume122
Issue number2
DOIs
StatePublished - Jul 31 1984

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Biophysics
  • Molecular Biology

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