QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bloj, B. Articles by Farias, R. N. Search for Related Content PubMed PubMed Citation Articles by Bloj, B. Articles by Farias, R. N.

Kinetic Modifications of the Acetylcholinesterase and (Ca²⁺ + Mg²⁺)-ATPase in Rat Erythrocytes by Cholesterol Feeding¹

Instituto de Quimica Biológica, Facultad de Bioquimica, Quimica y Farmacia, Universidad Nacional de Tucumán, Chacabuco 461, San Miguel de Tucumán, Tucumán, República Argentina

The influence of cholesterol on the membrane-bound acetylcholinesterase and (Ca²⁺ + Mg²⁺)-ATPase was studied in erythrocytes of five groups of male rats fed different fat-supplemented diets. Two groups of rats were fed essential fatty acid (EFA) sufficient diets with 5% lard or corn oil as the dietary fat, and two groups were fed EFA-deficient diets: a basic, fat-free diet and the same diet supplemented with 5% hydrogenated beef fat. One additional group of rats was fed a stock diet. The kinetic changes recorded were in the degree of the cooperativity of the inhibition by F^- of the acetylcholinesterase and the activation by Ca²⁺, and by Mg²⁺ of the (Ca²⁺ + Mg²⁺)-ATPase. The kinetic behavior of the enzymes was only modified by cholesterol feeding when they were bound to a membrane with a high fatty acid fluidity (e.g. derived from rats fed the corn oil-supplemented diet). The enzymes from a membrane with a low fatty acid fluidity (e.g. derived from rats fed a lard-supplemented diet) were not altered by cholesterol feeding. The changes were noticeable after 24 hours of cholesterol feeding. It is suggested that the in vivo cholesterol sites are involved in a regulatory mechanism for mammalian membrane-bound enzymes.

KEY WORDS: • acetylcholinesterase • (Ca²⁺ + Mg²⁺)-ATPase • cholesterol feeding • membrane fluidity

¹ Supported by grants from the Consejo Nacional de Investigaciones eientifieas y Tecnieas and Secretaria de Ciencia y Tecnica de la Universidad Nacional de Tucuman (Argentina).

² Present address: Division of Nutritional Sciences. Cornell University. Ithaea, N.Y. 14853 U.S.A.

³ Present address: Roger Adams Laboratory, Department of Biochemistry, University of Illinois. Urbana, Ill. 61801 U.S.A.

⁴ Career Jnvestigator of the Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina).

Manuscript received 20 April 1976.