Ranakinestatin-PPF from the Skin Secretion of the Fukien Gold-Striped Pond Frog, Pelophylax plancyi fukienensis: A Prototype of a Novel Class of Bradykinin Receptor Antagonist Peptide from Ranid Frogs
(a) Electrospray MS spectrum of a sample from reverse phase HPLC fraction #100 that contained bradykinin inhibitory activity. The doubly charged ion (m/z 1029.30), triply charged ion (m/z 686.99), and quadruply charged ion (m/z 515.59) of a peptide with a parent mass of 2056.4 Da were detected. (b) MS/MS fragmentation spectrum of the doubly charged ion at m/z 1029.30. (c) Theoretical singly and doubly charged b- and y-ion series arising from MS/MS fragmentation of the bradykinin inhibitory peptide with observed ions indicated in bold typeface and underlined.