02335nas a2200253   4500008004100000022001200041245015200053210006900205260000900274300001000283490000700293520141700300653002501717653001301742653002301755653003401778100002601812700002201838700002401860700002401884700002301908700002001931856013001951       2018                        eng d  a965174800aTripeptides derived from reactive centre loop of potato type II protease inhibitors preferentially inhibit midgut proteases of Helicoverpa armigera0 aTripeptides derived from reactive centre loop of potato type II   cAPR   a17-250 v953 a<p>Potato type II protease inhibitors (Pin-II PIs) impede the growth of lepidopteran insects by inhibiting serine protease-like enzymes in the larval gut. The three amino acid reactive centre loop (RCL) of these proteinaceous inhibitors is crucial for protease binding and is conserved across the Pin-II family. However, the molecular mechanism and inhibitory potential of the RCL tripeptides in isolation of the native protein has remained elusive. In this study, six peptides corresponding to the RCLs of the predominant Pin-II PIs were identified, synthesized and evaluated for in vitro and in vivo inhibitory activity against serine proteases of the polyphagous insect, Helicoverpa armigera. RCL peptides with sequences PRN, PRY and TRE were found to be potent inhibitors that adversely affected the growth and development of H. armigera. The binding mechanism and differential affinity of the RCL peptides with serine proteases was delineated by crystal structures of complexes of the RCL peptides with trypsin. Residues P1 and P2 of the inhibitors play a crucial role in the interaction and specificity of these inhibitors. Important features of RCL peptides like higher inhibition of insect proteases, enhanced efficacy at alkaline gut pH, longer retention and high stability in insect gut make them suitable molecules for the development of sustainable pest management strategies for crop protection.</p>10aHelicoverpa armigera10aProtease10aprotease inhibitor10aReactive centre loop peptides1 aSaikhedkar, Nidhi, S.1 aJoshi, Rakesh, S.1 aBhoite, Ashwini, S.1 aMohandasan, Radhika1 aYadav, Amit, Kumar1 aGiri, Ashok, P.  uhttps://library.ncl.res.in/content/tripeptides-derived-reactive-centre-loop-potato-type-ii-protease-inhibitors-preferentially