Interaction Mechanism of Cortisol and Catecholamines with Structural Components of Erythrocyte Membranes

Nonspecific mechanisms of the stress hormones interaction with erythrocyte membranes were studied by means of atomic force microscopy, fluorescence analysis, and IR spectroscopy. It was shown that stress hormones (cortisol, adrenaline, noradrenaline) can bind to erythrocyte membranes with high affinity (K-b similar to 10(6) M-1). The binding mechanism involves hydrogen bonds and hydrophobic and electrostatic interactions. Active groups of the hormones (NH2, NHCH3, keto, and hydroxy groups) interact simultaneously with CO and NH groups both of proteins and phospholipids. This leads to the formation of complex protein lipid domains that distort the surface of the erythrocyte membrane. Water dipoles are displaced from the domains to adjacent regions and facilitate membrane loosening. The interaction of hormones with the membrane is accompanied by structural transitions of disorder -> order (tangle -> alpha-helix, tangle -> beta-structure) in membrane proteins and structural transitions of order -> order in phospholipids. Formation of large domains (clusters) of the lipid protein and lipid nature leads to distortion of membranes and deteriorates their elasticity and rheological properties.