Some observations on biosynthesis and ratio regulation of mono- and digalactosyl diglycerides by chloroplasts and other subcellular fractions from spinach leaves

Abstract

Summary Evidence is presented that biosynthesis of galactolipids is influenced by enzymes involved in galactose metabolism. A soluble, heat labile inhibitor of protein nature is present in the 100,000 × g supernatant remaining after centrifugaron of a homogenate of spinach leaves. The ratio of monogalactosyl diglyceride to digalactosyl diglyceride in spinach chloroplasts is affected by freezing and thawing and by Triton X-100. Freezing and thawing of osmotically shocked chloroplasts increases monogalactosyl diglyceride formation, while addition of Triton X-100 results in a relative increase in digalactosyl diglyceride formation. The possibility of transfer of galactolipids between subcellular particles (mitochondria and microsomes) and chloroplasts is discussed.