Membrane bound proline iminopeptidase (PIP) from lactic acid bacteria (LAB) L. plantarum was extracted and purified using CM-sephadex, Sephadex G-100 and Q-sepharose column chromatography. PIP was purified with purification fold 7.13 and 33.5% yield. SDS-PAGE and MALDI-TOF revealed it as homodimer with molecular weight of 37.9 kDa and subunit of mass 18.9 kDa. Purified enzyme exhibited maximum activity at 45 °C and pH 7.0. Km and Vmax of purified PIP were 65 μM and 25.9 nm/min/ml respectively. Inhibition by PMSF confirmed it a serine protease. Metal ions and EDTA showed no effect on enzyme activity. The enzyme mainly hydrolysed Pro-4mβNA. The effectiveness of enzyme in purified form, membrane bound form and in combination with other enzymes to degrade collagen resulting in pharmaceutically significant collagen hydrolysates and in meat tenderization marks its industrial importance. There are very few PIPs are characterized from LAB, and therefore this study is industrially significant and brings some new knowledge into this area.
Keywords: Lactic acid bacteria; Lactobacillus plantarum; Meat tenderization; Probiotic; Proline iminopeptidase.
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