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Modification of Isoaspartyl Peptides and Proteins by Protein Carboxyl Methyltransferase from Bovine Brain

  • Dana W. Aswad
  • Brett A. Johnson
  • Esther L. Langmack
  • Jill M. Shirokawa
Part of the Advances in Experimental Medicine and Biology book series (NATO ASI F, volume 231)

Abstract

Recent findings indicate that protein carboxyl methyltransfer-ases (PCMTs) from mammalian brain and erythrocytes selectively and stoichiometrically methylate peptides and proteins which contain L-isoaspartyl (isoAsp) sites, i. e., aspartate which is linked via its side-chain β -carboxyl group, rather than via the typical α-carboxyl linkage (reviewed in reference 1). Why would an enzyme exhibit such an unusual specificity? As described below, we have undertaken several approaches to this question. First, we have explored the effect of sequence on the specificity of PCMT for isoAsp-containing peptides. Second, we have studied the effects of methylation on the structure and activity of isoAsp-containing peptides and proteins. Third, we have begun investigating possible sources of isoAsp under in vivo conditions. Our findings to date suggest that PCMT may play a role in the repair or degradation of isoAsp-bearing proteins which arise as a result of spontaneous deamidation of intrinsically labile asparagine sites.

Keywords

Partial Repair Cyclic Imide Normal Peptide Methyl Acceptor Protein Carboxyl 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1988

Authors and Affiliations

  • Dana W. Aswad
    • 1
  • Brett A. Johnson
    • 1
  • Esther L. Langmack
    • 1
  • Jill M. Shirokawa
    • 1
  1. 1.Department of PsychobiologyUniversity of California, IrvineIrvineUSA

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