On the differences in the sensitivity of coupling sites of submitochondrial particles to phospholipases A, C and and D.

Phospholipases A, C and D are widely used for studies on the structure of membranes of mitochondria [l-3], erythrocytes [4,5] and microsomes [6]. Information about the arrangement of phospholipids in the membrane can be obtained by elucidating the accessability of certain parts of phospholipid molecules to phospholipase attack. The sensitivity of various respiratory chain segments to cobra venom phospholipase A has been studied in this laboratory [7]. The data of the present work concern the sensitivity of various energy-linked functions of submitochondrial particles to phospholipases A, C and D. These data testify to the I and IV coupling sites, being of maximal sensitivity to phospholipase A, while coupling sites II @nd/or III are the most sensitive to phospholipases C and D.