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Subject: Biochemistry × Author: Grover, Sheetanshu × End date: 2018 × Start date: 2012 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Purification and characterization of protease inhibitors from pigeonpea (Cajanus cajan L.) and their interaction with Helicoverpa armigera (Hubner) proteases
    (PAU, 2015) Grover, Sheetanshu; Grewal, Satvir Kaur
    Ten pigeonpea genotypes were assessed for trypsin inhibitor (TI) status in leaves, flowers, pod walls, green seeds and mature seeds. TI interaction with purified Helicoverpa armigera trypsin was studied. Trypsin purified from H. armigera gut using Sephadex G-100 column chromatography was ~18.8 kDa, with optimum temperature and pH 50 °C and 11, respectively. TI content in leaves, flowers, pod walls and seeds increased with infestation ranging from 11 trypsin inhibitor units/g (TIU/g) to 33 TIU/g; 19 TIU/g to 38 TIU/g; 18 TIU/g to 55 TIU/g and 58 TIU/g to 181 TIU/g, respectively. Per cent inhibition of H. armigera gut proteases ranged from 19 to 43 % with infested leaves, 20 to ~ 51 % with flowers and 25 to 36 % with seeds. TI content in pigeonpea mature seeds varied from 147.75 TIU/g (in AL 201) to 177.85 TIU/g (AL 1495). SDS-PAGE of seed extracts revealed proteins of molecular weight ranging from 15.6 kDa to 98.5 kDa. Using gelatin SDS-PAGE, six different TIs with bovine trypsin were identified and four of them (Rm 0.39, 0.78, 0.84 and 0.93) were present in all the genotypes. Five H. armigera protease inhibitors (PIs) were detected using the gelatin SDS-PAGE. The purified inhibitor from mature seeds corresponds to ~17.3 kDa, with optimum temperature 50 ºC. pH optima for genotypes AL 1770 and AL 1677 were neutral (7.0) and alkaline (12.0). For AL 1753, pH optima were 7.0 and 10.0. Purified TI from pigeonpea inhibited purified trypsin nearly competitively.