17554-05-1 Boc-leu-(31)-cck4 Boc-trp-leu-asp-phe-NH2 Btlasp-NH2 Butyloxycarbonyl-tryptophyl-leucyl-aspartyl-phenylalaninamide Cholecystokinin (4), butyloxycarbonyl-leu(31)- L-Phenylalaninamide, N-((1,1-dimethylethoxy)carbonyl)-L-tryptophyl-L-leucyl-L-alpha-aspartyl-