Proline at position 14 of alamethicin is essential for hemolytic activity, catecholamine secretion from chromaffin cells and enhanced metabolic activity in endothelial cells

• Published in: Biochimica et biophysica acta 1998-03, Vol.1370 (1), p.175-183
• Main Authors: Dathe, Margitta, Kaduk, Christine, Tachikawa, Eiichi, Melzig, Matthias F, Wenschuh, Holger, Bienert, Michael
• Format: Article
• Language: English
• Subjects: Alamethicin; Alamethicin - chemistry; Alamethicin - metabolism; Alamethicin - pharmacology; Amino Acid Sequence; Animals; Catecholamine secretion; Catecholamines - metabolism; Cattle; Chromaffin Cells - metabolism; Conformation; Dye release; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Hemolysis - drug effects; Hemolytic activity; Humans; Metabolic activity; Molecular Sequence Data; oligopeptides; Proline - chemistry; Proline - physiology; Structure-Activity Relationship
• ISSN: 0005-2736; 0006-3002; 1879-2642; 1878-2434
• DOI: 10.1016/S0005-2736(97)00260-5

Alamethicin is known to lyse different biological cells and to induce voltage dependent ion channels in lipid bilayers. A set of analogs with proline shifted from position 14 in the native peptide towards the N- and C-terminus was used to investigate the role of proline in: (i) alamethicin induced hemolysis of human red blood cells, (ii) stimulation of catecholamine secretion from bovine adrenal chromaffin cells and (iii) induction of metabolic activity in bovine aortic endothelial cells. Half maximal hemolytic activity was found at 30 μM alamethicin concentration, complete lysis occurred at 100 μM. The stimulation of catecholamine secretion in the presence of extracellular Ca 2+ was concentration dependent up to 50 μM alamethicin. At this high concentration mild secretion was also found in the absence of Ca 2+ indicating cell membrane damage. Alamethicin transiently stimulated the metabolic rate of endothelial cells in a concentration dependent mode up to 20 μM while the inhibition of metabolism at higher concentrations pointed to a toxic effect. The alamethicin analogs were completely inactive in all the biological assays. The effects correlated with a loss of dye release inducing activities on phosphatidylcholine vesicles and reduction of channel forming properties in lipid bilayers and were associated with modifications of membrane affinity rather than conformational changes of the peptides. The results indicate that proline at position 14 of the native peptide is essential for the interaction with different membrane systems.