Carnitine palmitoyltransferase and carnitine octanoyltransferase activities in brain mitochondrial fractions were approx. 3-4-fold lower than activities in liver. Estimated Km values of CPT1 and CPT2 (the overt and latent forms respectively of carnitine palmitoyltransferase) for L-carnitine were 80 microM and 326 microM, respectively, and K0.5 values for palmitoyl-CoA were 18.5 microM and 12 microM respectively. CPT1 activity was strongly inhibited by malonyl-CoA, with I50 values (concn. giving 50% of maximum inhibition) of approx. 1.5 microM. In the absence of other ligands, [2-14C]malonyl-CoA bound to intact brain mitochondria in a manner consistent with the presence of two independent classes of binding sites. Estimated values for KD(1), KD(2), N1 and N2 were 18 nM, 27 microM, 1.3 pmol/mg of protein and 168 pmol/mg of protein respectively. Neither CPT1 activity, nor its sensitivity towards malonyl-CoA, was affected by 72 h starvation. Rates of oxidation of palmitoyl-CoA (in the presence of L-carnitine) or of palmitoylcarnitine by non-synaptic mitochondria were extremely low, indicating that neither CPT1 nor CPT2 was likely to be rate-limiting for beta-oxidation in brain. CPT1 activity relative to mitochondrial protein increased slightly from birth to weaning (20 days) and thereafter decreased by approx. 50%.
Skip Nav Destination
Article navigation
February 1985
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
- PDF Icon PDF LinkAdvertising
Research Article|
February 15 1985
Carnitine acyltransferase activities in rat brain mitochondria. Bimodal distribution, kinetic constants, regulation by malonyl-CoA and developmental pattern
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1985 London: The Biochemical Society
1985
Biochem J (1985) 226 (1): 323–330.
Citation
M I Bird, L A Munday, E D Saggerson, J B Clark; Carnitine acyltransferase activities in rat brain mitochondria. Bimodal distribution, kinetic constants, regulation by malonyl-CoA and developmental pattern. Biochem J 15 February 1985; 226 (1): 323–330. doi: https://doi.org/10.1042/bj2260323
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.