3
Views
3
CrossRef citations to date
0
Altmetric
Original

Reversible Inhibition of LCAT by Penicillins. Kinetic and Mechanistic Investigations

, M.D.
Pages 26-31 | Published online: 14 Feb 2011
 

Abstract

A simple and rapid method is described for labelling serum lipoproteins with 3H cholesterol. According to the tracer data as well as cholesterol analyses, the velocity of ester formation in rat sera and β-lipoprotein-depleted human sera decreased during incubations as a first order reaction. This suggests a level of chemical activity for cholesterol far below the Km of the enzyme. The reversible inhibition by three different penicillins showed a dependency of the inhibitor concentration which supports this notion. 50 per cent inhibition of the rat enzyme was obtained with 0.1 mM dicloxacillin, 0.3 mM benzylpenicillin, and 1.4 mM methicillin (water phase concentrations). The human enzyme was about 10-fold less sensitive. The mechanism of penicillin inhibition, investigated by stripping-recombination experiments with the 20-fold purified rat enzyme chromatographed on penicillin-loaded Sephadex G-25 columns, was found to be a dissociation of the enzyme into two components, an inactive apoenzyme and a coenzyme with a molecular weight below 1000.

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.