Neuropeptide Y acylation chemistry in aqueous solution: significance to synthesis of a peptide-based photoaffinity label.
Treatment of neuropeptide Y (NPY, 1) for 20 hr with a 20 equivalent excess of N-propionyl succinimide (2) in 10 mM phosphate buffer, pH 6.0, yields NPY and N alpha-propionyl-NPY (3) as major products, and at pH 7.5 the major product is N alpha, N epsilon-dipropionyl-NPY. However, acylation of NPY with one equivalent of N-(5-azido-2-nitrobenzolyloxy)-succinimide (5) is more rapid, yielding N alpha-(5-azido-2-nitrobenzoyl)-NPY (6) in 70% conversion yield after only 5 min. Thus, in spite of its increased reactivity, the N-hydroxysuccinimide active ester shows enhanced alpha- vs. epsilon-NH2 selectivity relative to 2. The activities of 3, 4, and 6 as reversible, competitive ligands at rat brain NPY binding sites and of 6 as an irreversible photoaffinity label are reported.
Hu
L
L
Department of Medicinal Chemistry, University of Kansas, Lawrence 66045-2506.
Doughty
M B
MB
D000215:Acylation; D000345:Affinity Labels; D000595:Amino Acid Sequence; D007931:Leucyl Aminopeptidase; D008969:Molecular Sequence Data; D009478:Neuropeptide Y / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D012996:Solutions; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013388:Succinimides
D000345:Affinity Labels; D009478:Neuropeptide Y; D010446:Peptide Fragments; D012996:Solutions; D013388:Succinimides; C087949:N-propionylsuccinimide; D007931:Leucyl Aminopeptidase