01833nas a2200241   4500008004100000022001400041245012600055210006900181260000800250300001400258490000700272520099600279653001301275653002201288653002001310653002901330653001201359100002201371700001901393700002801412700002601440856012501466       2019                        eng d  a0739-110200aStructural insights into the unique inhibitory mechanism of Kunitz type trypsin inhibitor from Cicer arietinum L. Vol. 370 aStructural insights into the unique inhibitory mechanism of Kuni  cJUL  a2669-26770 v373 a<p>Kunitz-type trypsin inhibitors bind to the active pocket of trypsin causing its inhibition. Plant Kunitz-type inhibitors are thought to be important in defense, especially against insect pests. From sequence analysis of various Kunitz-type inhibitors from plants, we identified CaTI2 from chickpea as a unique variant lacking the functionally important arginine residue corresponding to the soybean trypsin inhibitor (STI) and having a distinct and unique inhibitory loop organization. To further explore the implications of these sequence variations, we obtained the crystal structure of recombinant CaTI2 at 2.8 angstrom resolution. It is evident from the structure that the variations in the inhibitory loop facilitates non-substrate like binding of CaTI2 to trypsin, while the canonical inhibitor STI binds to trypsin in substrate like manner. Our results establish the unique mechanism of trypsin inhibition by CaTI2, which warrant further research into its substrate spectrum.</p>
10aChickpea10acrystal structure10ainhibitory loop10aKunitz trypsin inhibitor10aTrypsin1 aBendre, Ameya, D.1 aSuresh, C., G.1 aShanmugam, Dhanasekaran1 aRamasamy, Sureshkumar  uhttps://library.ncl.res.in/content/structural-insights-unique-inhibitory-mechanism-kunitz-type-trypsin-inhibitor-cicer-002329nas a2200229   4500008004100000022001400041245010400055210006900159260000800228300001200236490000700248520151100255653001301766653003601779653003801815653002501853653002901878100002201907700001701929700002601946856012701972       2020                        eng d  a1572-388700aFunctional stability and structural transitions of a kunitz trypsin inhibitor from chickpea (CaTI2)0 aFunctional stability and structural transitions of a kunitz tryp  cAUG  a350-3570 v393 a<p>Enzymes are important tools for various applications. We have studied structural transitions and functional stability of a Kunitz trypsin inhibitor from Chickpea (CaTI2), a potent insect gut-protease inhibitor, under different stress conditions like non-neutral pH, elevated temperature and co-solvent concentrations. CaTI2 was cloned and expressed in an eukaryotic systemP. pastorisand was investigated for conformational transitions using circular dichroism spectroscopy, differential scanning fluorimetry and activity assay. Native CaTI2 has a sheet dominant structure with 40% beta sheets and possess a single tryptophan residue situated in the hydrophobic core of the enzyme. The recombinant inhibitor maintained its maximum activity under alkaline pH with its secondary structure intact between pH 6-10. CaTI2 was observed to be thermally stable up to 55 degrees C with aT(m) of 61.3 degrees C above which the protein unfolds. On treating with chemical denaturant (urea), the CaTI2 lost its inhibitory potential and native conformation beyond 2 M urea concentration. Moreover, the protein unfolded at lower temperatures as the concentration of denaturant increased, suggesting more complex structural changes. Further, the stability of the inhibitor was found to be directly proportional to the solvent polarity. The data, herein offers significant information of inhibitor stability and activity which could be exploited for its further development into an effective pesticide. [GRAPHICS] .</p>
10aChickpea10aCircular dichroism spectroscopy10aDifferential scanning fluorimetry10aFunctional stability10aKunitz trypsin inhibitor1 aBendre, Ameya, D.1 aShukla, Ekta1 aRamasamy, Sureshkumar  uhttps://library.ncl.res.in/content/functional-stability-and-structural-transitions-kunitz-trypsin-inhibitor-chickpea-cati2