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Thylakoids and appetite regulation

Collaboration: Charlotte Erlanson-Albertsson

This is an entirely new and unique project, which I carry out together with scientists at the Biomedical Centre and Department of Food Technology and Department of Biochemistry (see publications: Biochemical Journal 401:727-733, 2007).

The project is based on the discovery that addition of thylakoids to food reduces food intake and body weight of growing rats and mice. A prolongation of fat digestion and concomitant release of satiety hormones and reduction of hunger peptides cause the effect. This prolongation of fat digestion is due to a reduction of lipolysis by the pancreas lipase-colipase complex which in turn is due to binding of the complex to the thylakoids which in turn are adsorbed to emulsified fat droplets and thereby hinder the lipase-colipase complex to come in contact with the lipid substrate. Sooner or later the thylakoids themselves are degraded by proteases and the body will eventually take up the fat. However, the satiety induced by the prolongation results in a net reduction of food intake.

The main components of the thylakoids that are responsible for the reduction of lipolysis are the hydrophobic transmembrane polypeptide chains of the protein complexes of the membrane. We have shown that other membranes share the in vitro effect of thylakoids and also isolated membranes proteins and polypeptides. Thus, we have an interesting trilogy of a colloidal system involving two interacting surfaces, lipid surface and thylakoid membrane surface, together with an enzyme complex, lipase-colipase, of a formidable complexity and a challenge for physicochemical studies.