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The contribution of helical potential to the in vitro receptor binding activity of a neuropeptide Y N‐terminal deletion fragment
Author(s) -
Doughty Michael B.,
Hu Longqin
Publication year - 1993
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360330806
Subject(s) - neuropeptide y receptor , chemistry , antiparallel (mathematics) , helix (gastropod) , proline , stereochemistry , receptor , in vitro , crystallography , neuropeptide , amino acid , biochemistry , biology , ecology , physics , quantum mechanics , snail , magnetic field
Abstract In its dimeric form neuropeptide Y (NPY) folds into a compact structure in which the antiparallel oriented proline and α‐helices apparently associate to form a primitive hydrophobic core. To investigate the contribution of helical stability to the receptor binding activity of NPY and its N‐terminal deletion fragments, we synthesized and studied the solution conformational properties and in vitro activities of NPY, N α ‐acetyl‐NPY 2–36 , NPY 15–36 , N α ‐propinonly‐NPY 15–36 , and N α ‐succinyl‐NPY 15–36 is significantly less helical than both NPY and N α ‐acetyl‐NPY 2–36 , and this decreased helical potential is attributed of the absence of the intramolecular stabilizing interaction afforded by the proline helix in the latter analogues. However, in accord with the helix dipole model, the helical potential of NPY 15–36 is significantly increased by N‐terminal succinlyation, whereas propionylation has no effect. In addition to an increase in helical potential, N α ‐succinyl‐NPY 15–36 is 2.5 and 4.6 times more active than NPY 15–36 and N α ‐propionly‐NPY 15–36 , respectively and is equipotent with N α ‐acteyl‐NPY 2–36 in displacing 1m M [ 3 H]‐NPY from specific binding sites in rat brain membranes. The demonstration of positive correlation between % α‐helix content and in vitro binding activity suggests that the helical potential of N‐terminal NPY deletion fragments contributes to their in vitro activity in the rat brain, and that a second role of the proline helix might be to stabilize the receptor‐active conformation of the NPY α‐helix. © 1993 John Wiley & Sons, Inc.