Cathepsin Y (a novel thiol enzyme) produces kinin potentiating peptide from the component protein of rat plasma

Rat spleen cathepsin Y (a novel enzyme) that produces bradykinin (BK) poten tiating peptide (BPP) from rat plasma was isolated, characterized and its a mino acid sequence was deduced from cDNA cloned by reverse transcription-po lymerase chain reaction (RT-PCR). We propose the name cathepsin Y for this enzyme considering its origin, characteristics and the amino acid sequence. BPP potentiates not only BK but also lysyl-BK (lysBK) and T-kinin (TK) act ion on uterus contraction. The structure of BPP is Pro-Pro-Pro-Leu-Gly-Pro- Gly-Ser. The magnitude of the potentiation of BK activity by synthesized BP P was seven-fold when equivalent quantities added to BK and 23-fold when th e level is doubled. The precursor proteins that produce BPP by the action o f cathepsin Y are elated into two fractions when the heated plasma was appl ied to a negative ion exchange column. Structure relationships between thes e two proteins are now under investigation. In this paper, we report on the characteristics and the amino acid sequence of rat spleen cathepsin Y, its structure and the potentiating activity of BPP, and isolation of the precu rsor protein. (C) 1999 Published by Elsevier Science B.V. All rights reserv ed.