163136-31-0 2,3,4,5-Tetradehydroprolyl-2-aminobutanoyl-seryl-3-phenyl-beta-alanyl-2-aminobutanoic acid Asterinin D Butanoic acid, 2,3,4,5-tetradehydroprolyl-L-2-aminobutanoyl-L-seryl-(R)-3-phenyl-beta-alanyl-L-2-amino- delta(2,4)-Pro-L-abu-L-ser-L-betaphe-L-abu delta(2,4)-Pro-abu-ser-betaphe-abu