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Increased affinity of choline acetyltransferase for choline in Alzheimer's disease: a steady-state kinetic study

Academic Article
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Overview

authors

  • Nordstrom, O.
  • Eliaz, M.
  • Bartfai, Tamas
  • Gottfries, C. G.

publication date

  • September 1987

journal

  • Brain Research  Journal

abstract

  • The steady-state kinetics of choline acetyltransferase (CAT) from autopsy samples of human caudate nucleus of aged controls and of patients with Alzheimer's disease was studied. In 10 samples from Alzheimer's disease-afflicted brains the affinity for the limiting substrate choline (Ch) was significantly higher: Michaelis constant KmCh was for these samples 1.93 +/- 0.72 mM while in the samples from 9 age-matched controls KmCh was 2.53 +/- 0.78 mM. The difference is statistically significant (P less than 0.05). Endogenous choline concentrations in the samples were 124 +/- 39 (n = 10) nmol/g wet wt. in the Alzheimer's disease-afflicted samples and 180 +/- 57 (n = 9) nmol/g wet weight (n = 9) in the control samples (P less than 0.05). The initial velocity at 70 microM acetyl co-enzyme (AcCoA) in Alzheimer's samples was 171.5 +/- 131.0 pmol [14C]acetyl choline [14C]ACh/mg protein/min as compared to the controls 422.1 +/- 231.0 pmol [14C]ACh/mg protein/min replicating many previous findings about decline of CAT activity in Alzheimer's disease. However, in the same samples the affinity for the other substrate acetyl-CoA (AcCoA) was significantly lower for the Alzheimer patients, KmAcCoA = 61 +/- 40 microM, than for the age-matched control patients, KmAcCoA = 28 +/- 8 microns (P less than 0.01). The data suggest some compensation of the loss of enzyme molecules via changed affinity for the limiting substrate, Ch.

subject areas

  • Aged
  • Aged, 80 and over
  • Alzheimer Disease
  • Caudate Nucleus
  • Choline
  • Choline O-Acetyltransferase
  • Female
  • Humans
  • Kinetics
  • Male
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Identity

International Standard Serial Number (ISSN)

  • 0006-8993

Digital Object Identifier (DOI)

  • 10.1016/0006-8993(87)91259-5

PubMed ID

  • 3676768
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Additional Document Info

start page

  • 371

end page

  • 374

volume

  • 420

issue

  • 2

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