Protein L-isoaspartyl methyltransferase in postmortem brains of aged humans

Brett A. Johnson, Jill M. Shirokawa, James W. Geddes, Ben H. Choi, Ronald C. Kim, Dana W. Aswad

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


The specific activity of protein L-isoaspartyl methyltransferase, an enzyme implicated in the metabolism of damaged, isoaspartate-containing proteins, has been measured in postmortem samples of parietal cortex from 30 individuals (19 with Alzheimer's disease and 11 controls). Methyltransferase specific activity was positively correlated with age at death, increasing by 2.9 pmol/min/mg of protein for every ten years of age (r = .51, p<0.005). This correlation was significant in the control and Alzheimer's disease groups alike. Specific activity also appeared to be about 15% higher in females than in age- and diagnosis-matched males (p<0.05). No significant differences were observed between age- and sex-matched Alzheimer patients and controls, suggesting that a deficiency in this enzyme is not responsible for the accumulation of abnormal proteins in Alzheimer's disease.

Original languageEnglish
Pages (from-to)19-24
Number of pages6
JournalNeurobiology of Aging
Issue number1
StatePublished - 1991

Bibliographical note

Funding Information:
This work was supported by United States Public Health Service grants AG-00538 and NS-17269 and by Research Career Development Award NS-01082, all to D.W.A.


  • Aging
  • Alzheimer's disease
  • Isoaspartate
  • Methylation
  • Protein carboxyl methyltransferase
  • Sex difference

ASJC Scopus subject areas

  • Clinical Neurology
  • Geriatrics and Gerontology
  • Aging
  • General Neuroscience
  • Developmental Biology


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