Institute of Fundamental Technological Research

A proline iminopeptidase (EC. 3.4.11.5) was isolated from shoots of 3 day old seed lings. The purification procedure consisted of 5 steps: acid precipitation, gel filtration on Sephadex G-200, ion-exchange chromatography on Sepharose CL 6B, twice repeated hydrophobic chromatography on Phenyl- Sepharose HP. The enzyme was purified 404.8-fold, with the specific activity of 8.5 units•mg-1of protein with recovery yield of 3 %. The purified enzyme had a molecular mass of 225 kDa estimated by gel filtration and 55.4 kDa by SDS PAGE. This indicates that native enzyme is com posed of four subunits. The enzyme was specific for proline -naphtylamide among various amino acid -naphtylamides.
An optimal activity was observed at 37 °C at pH 7.75. The enzyme was thermostable up to 37 °C for 30 min. The enzyme was strongly inhibited by pHMB, E-64, heavy metal ions and partially by PMSF, DFP. The results suggest that cysteine and serine residues may participate in the enzyme activity.

proline iminopeptidase, exopeptidases, purification, characteristics, rye