A NOVEL D-AMINO-ACID-CONTAINING PEPTIDE ISOLATED FROM APLYSIA HEART

A novel cardio excitatory peptide was purified from the hearts of Aply sia kurodai. The peptide was a tripeptide containing a D-amino acid re sidue in the second position, Asn-D-Trp-Phe-NH2 (NdWFamide). NdWFamide increased the amplitude of contractions of the perfused Aplysia heart with little effect on beating frequency, showing a threshold of appro ximately 10(-11)M. The peptide also potentiated spontaneous contractio ns of the anterior aorta. The synthetic peptide having L-Trp instead o f D-Trp was about 1,000 times less potent than the native one. NdWFami de seems 60 play an important role in regulation of cardiac activity i n Aplysia. (C) 1997 Academic Press.