Incorporation of 15N-labeled ammonia into glutamine amide groups by protein-glutaminase and analysis of the reactivity for α-lactalbumin

Noriko Miwa, Nobuhisa Shimba, Mina Nakamura, Keiichi Yokoyama, Noriki Nio, Eiichiro Suzuki, Kenji Sonomoto

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Protein-glutaminase (PG) is an enzyme that catalyzes the deamidation of protein-bound glutamine residues. We found that an enzyme labeling technique (ELT), which is a stable isotope labeling method based on transglutaminase (TGase) reaction, is applicable for PG. PG catalyzed incorporation of 15N-labeled ammonium ions into reactive glutamine amide groups in α-lactalbumin similarly to TGase and deamidated the most reactive glutamine amide group once labeled with 15N. Furthermore, we investigated the effect of ammonium ions on the PG activity by peptide mapping, and more reactive glutamine residues were detected than were detected by the ELT in the presence of ammonium ions. This is probably because ammonium ions are competitive inhibitors, causing decreased reactivity for glutamine residues. We propose the reaction scheme of PG in the presence of the 15N-labeled ammonium ions and show that the ELT method with PG is useful for evaluating the activity of PG.

Original languageEnglish
Pages (from-to)12752-12760
Number of pages9
JournalJournal of Agricultural and Food Chemistry
Volume59
Issue number24
DOIs
Publication statusPublished - Dec 28 2011

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

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