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A novel D-amino-acid-containing peptide isolated from Aplysia heart
F Morishita1, Y Nakanishi, S Kaku
1Department of Biological Science, Faculty of Science, Hiroshima University, Japan. morishit@alpha04.sci.hiroshima-u.ac.jp
Abstract:
A novel cardio-excitatory peptide was purified from the hearts of Aplysia kurodai. The peptide was a tripeptide containing a D-amino acid residue 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 approximately 10(-11) M. The peptide also potentiated spontaneous contractions of the anterior aorta. The synthetic peptide having L-Trp instead of D-Trp was about 1,000 times less potent than the native one. NdWFamide seems to play an important role in regulation of cardiac activity in Aplysia.