Alpha-helical structure of vasoactive intestinal peptide is essential to its biological functions

摘要

We previously investigated the effects of VIP/PACAP chimeric peptides on receptor binding,activation of adenylate cyclase,attenuation of nitric oxide synthase and neurite outgrowth in PC 12 cells,demonstrating that the random coil structures a.t the N-terminuses of VIP and PACAP are necessary to exhibit these biological activities and specificities for the recognition of each specific receptor.On the other hand,the role of the long alpha-helical structure in the C-terminus of VIP has not been fully elucidated.Other investigators showed that excessive amounts of VIP-(10-28)and PACAP-(6-27),corresponding sequences to the a-helical components for VIP and PACAP,competitively inhibited bindings of VIP and PACAP to VPAC1/2 receptors and PAC1 receptor(PACAP-specific receptor),respectively,suggesting that the a-helical components of VIP and PACAP strongly influence their biological functions.