01985nas a2200169   4500008004100000245011800041210006900159260000800228300000800236490000700244520137200251100001701623700001701640700001801657700001701675856012301692       2018                        eng d00aStructural insights into the unique inhibitory mechanism of Kunitz type trypsin inhibitor from Cicer arietinum L.0 aStructural insights into the unique inhibitory mechanism of Kuni  cNOV  a1-90 v243 aKunitz-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 2.8Å 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. Abbreviations BApNA Nα-Benzoyl-L-arginine 4-nitroanilide BPT bovine pancreatic trypsin CaTI2 Cicer arietinum L trypsin inhibitor 2 DrTI Delonix regia Trypsin inhibitor EcTI Enterolobium contortisiliquum trypsin inhibitor ETI Erythrina caffra trypsin inhibitor KTI Kunitz type inhibitor STI soybean trypsin inhibitor TKI Tamarindus indica Kunitz inhibitor Communicated By Ramaswamy H. Sarma.1 aBendre, A.D.1 aSuresh, C.G.1 aShanmugam, D.1 aRamasamy, S.  uhttps://library.ncl.res.in/content/structural-insights-unique-inhibitory-mechanism-kunitz-type-trypsin-inhibitor-cicer