Interaction of amphiphiles with integral membrane proteins. I. Structural destabilization of the anion transport protein of the erythrocyte membrane by fatty acids, fatty alcohols, and fatty amines.
The effect of model amphiphiles on the structural stability of the anion exchange protein (band 3) of the human erythrocyte membrane was studied by differential scanning calorimetry. The concentration of membranes, as well as the concentration, head group, alkyl chain length, degree of unsaturation, and double bond configuration of a variety of alkane derivatives were all varied in a systematic way. The depression of the denaturation temperature of band 3 per unit membrane concentration of the amphiphile was then determined in order to quantitate the potency of each drug. Saturated fatty acids of chain length C8 to C24 displayed a monotonic decrease in potency up to C20, followed by a dramatic diminution in potency at C22 and C24. Unsaturation caused only minor increases in the abilities of fatty acids to perturb the anion exchanger, and surprisingly, there was neither a trend for the number of double bonds nor a significant cis-trans distinction. Arachidonic acid, as an exception, was much more effective than any other amphiphile in destabilizing band 3. Fatty acids were about three times more potent than fatty amines and fatty alcohols; however, the enhanced partitioning of the latter into the membrane compensated at certain membrane/buffer ratios for its reduced intrinsic potency. A quantitative model interpretation of the data is presented in an accompanying paper.
Gruber
H J
HJ
Department of Chemistry, Purdue University, West Lafayette, IN.
Low
P S
PS
D000588:Amines; D001457:Anion Exchange Protein 1, Erythrocyte; D002152:Calorimetry, Differential Scanning; D004910:Erythrocyte Membrane / Q000648:ultrastructure; D005227:Fatty Acids; D005233:Fatty Alcohols; D006801:Humans; D066298:In Vitro Techniques; D011489:Protein Denaturation; D012995:Solubility; D013329:Structure-Activity Relationship
D000588:Amines; D001457:Anion Exchange Protein 1, Erythrocyte; D005227:Fatty Acids; D005233:Fatty Alcohols