Analysis of latent forms of renin using antibodies raised against the propart segment of human prorenin: validation with representative samples of ovarian cyst and follicular fluids.

Antisera were raised against synthetic peptides from the prosegment of human prorenin. The use of each of these for detection of the appropriate prosegment region of prorenin was validated by development of an ELISA protocol standardised with recombinant prorenin present in culture medium conditioned by myeloma cells transfected with a prorenin expression plasmid. Detection of the respective epitopes in the prosegment required prior exposure of the prorenin in the medium to acid pH in order to partially unfold the prorenin molecule by dislodging the prosegment from the main body of the protein. By these ELISA protocols, the form of latent renin present in representative samples from ovarian cyst and follicular fluids was analysed; one follicular cyst fluid was found to contain full-length prorenin whereas the fluid from a benign cyst and ovarian follicular fluid samples contained the precursor in truncated form.