title: Cryoprotective effect of glycine betaine and glycerol is not based on a single mechanism.
abstract: The mechanism of action of the osmoregulatory substances glycine betaine and glycerol in the course of the freeze-thaw cycle was studied. Photochemical activity of isolated thylakoid membranes was effectively protected during freezing by both solutes by preventing dissociation of the peripheral cold labile proteins - the water splitting system and plastocyanin. It is suggested that the cryoprotective effect of glycine betaine and glycerol is based on a mechanism similar to the well documented stabilization of complex enzymes against dissociation into subunits at high salt concentrations. Specific solute-membrane interactions additionally contribute to the observed cryoprotective effect. The binding of the molecules of glycine betaine and glycerol is limited to the water lipid interface of thylakoid membranes.
authors.affiliation: Institute of Biophysics, Bulgarian Academy of Sciences, Acad. G. Bonchev str. bl. 21, 1113 Sofia, Bulgaria. popova@obzor.bio21.bas.bg
authors.forename: A V
authors.initials: AV
authors.lastname: Popova
authors.forename: M R
authors.initials: MR
authors.lastname: Busheva
mesh_terms: D001622:Betaine; D003451:Cryoprotective Agents; D005615:Freezing; D005990:Glycerol; D008560:Membrane Fluidity; D018532:Pisum sativum; D010777:Photochemistry; D017694:Rewarming; D020524:Thylakoids / Q000737:chemistry*; D014882:Water-Electrolyte Balance
chemical_list: D003451:Cryoprotective Agents; D001622:Betaine; D005990:Glycerol