Association of lipids and proteins in chloroplast lamellar membrane

Abstract

1. 1. To study the nature of lipid association with protein in biological membranes, lipids with different hydrophilic groups were reassociated with chloroplast membrane proteins. 2. 2. For stoichiometric reassociation of lipids with protein, a convenient method, a double dialysis procedure, was developed and its validity was examined. 3. 3. Saturation of lipid association occurred when 36 moles of palmitic acid, 30 moles of chlorophyll, 16 moles of monogalactosyl diglyceride, 15 moles of phosphatidyl glycerol or digalactosyl diglyceride, 6 moles of dihydrophytyl ether phosphatidyl glycerophosphate or 1 mole of β-carotene was bound per mole of lamellar protein. 4. 4. In the presence of competitors, reassociation of monogalactosyl diglcyeride or chlorophyll with protein was shown to be dependent upon the nature of the hydrophobic moiety of competing amphipathic lipids and independent of their hydrophilic groups. 5. 5. These data provide evidence for hydrophobic association of lipids with chloroplast lamellar proteins.