Fig. 3

Molecular mass analysis of fragments generated by KAL digestion of pro-renin; identification of active renin and pro-peptide fragments. a Recombinant pro-renin was digested with KAL as described in Fig. 2 and subjected to SDS-PAGE; 10 % gel (left panel) for separation of active renin from pro-renin and 4–12 % gel (right panel) for identification of lower (~5 kDa) fragment). Fragments were numbered as 1 (pro-renin), 2 (active renin) and 3 (pro-peptide). M1 and M2 are SDS-PAGE molecular weight standards in broad range and low range respectively b Fragment 2 and 3 were cut out and subjected to trypsin digestion and LC-MS/MS analysis separately for identification. Peptide coverage (bold type) identified by MS/MS in the termini of pro-peptide (from fragment 3) and active renin (from fragment 2) is shown. c Quantification of the MS data. The total sum of pro-peptide and active renin spectra observed were normalized by the amino acid length (43 for pro-peptide and 340 for the active renin) to represent the pro-peptide to active renin ratio in gel fragments 2 or 3