02696nas a2200301 4500008004100000022001400041245016000055210006900215260010600284300000900390490000700399520155800406653001301964653001801977653002801995653002902023653001502052653002402067100002402091700002002115700001902135700002002154700002202174700002302196700002602219700002002245856012902265 2016 eng d a0965-174800aCharacterization of two coleopteran alpha-amylases and molecular insights into their differential inhibition by synthetic alpha-amylase inhibitor, acarbose0 aCharacterization of two coleopteran alphaamylases and molecular  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcJUL a1-110 v743 a

Post-harvest insect infestation of stored grains makes them unfit for human consumption and leads to severe economic loss. Here, we report functional and structural characterization of two coleopteran alpha-amylases viz. Callosobruchus chinensis alpha-amylase (CcAmy) and Tribolium castaneum alpha-amylase (TcAmy) along with their interactions with proteinaceous and non-proteinaceous alpha-amylase inhibitors. Secondary structural alignment of CcAmy and TcAmy with other coleopteran alpha-amylases revealed conserved motifs, active sites, di-sulfide bonds and two point mutations at spatially conserved substrate or inhibitor binding sites. Homology modeling and molecular docking showed structural differences between these two enzymes. Both the enzymes had similar optimum pH values but differed in their optimum temperature. Overall, pattern of enzyme stabilities were similar under various temperature and pH conditions. Further, CcAmy and TcAmy differed in their substrate affinity and catalytic efficiency towards starch and amylopectin. HPLC analysis detected common amylolytic products like maltose and maltotriose while glucose and malto-tetrose were unique in CcAmy and TcAmy catalyzed reactions respectively. At very low concentrations, wheat alpha-amylase inhibitor was found to be superior over the acarbose as far as complete inhibition of amylolytic activities of CcAmy and TcAmy was concerned. Mechanism underlying differential amylolytic reaction inhibition by acarbose was discussed. (C) 2016 Elsevier Ltd. All rights reserved.

10aAcarbose10aalpha-amylase10aalpha-amylase inhibitor10aCallosobruchus chinensis10aColeoptera10aTribolium castaneum1 aChannale, Sonal, M.1 aBhide, Amey, J.1 aYadav, Yashpal1 aKashyap, Garima1 aPawar, Pankaj, K.1 aMaheshwari, V., L.1 aRamasamy, Sureshkumar1 aGiri, Ashok, P. uhttps://library.ncl.res.in/content/characterization-two-coleopteran-alpha-amylases-and-molecular-insights-their-differential02635nas a2200229 4500008004100000022001400041245012200055210006900177260000800246300001100254490000900265520184800274653001602122653001802138653002802156653001102184653002702195100002202222700002202244700002002266856011902286 2020 eng d a0304-416500aMolecular determinant for specificity: differential interaction of alpha-amylases with their proteinaceous inhibitors0 aMolecular determinant for specificity differential interaction o cDEC a1297030 v18643 a

Background: alpha-Amylase inhibitors (alpha-AIs) belong to the discrete classes, and exhibited differential specificities against alpha-amylases from various sources. Several alpha-amylases and their complexes with inhibitors at the molecular level have been studied in detail. Interestingly, some alpha-AIs depict specific and selective interactions amid different insect alpha-amylases. Scope of review: There are studies to understand evolutionary variability and functional differentiation of insect alpha-amylases and their cognate inhibitors. We have examined sequence, structural, and interaction diversity between various alpha-amylases and alpha-AIs. Based on these analyses, we are providing a potential basis for the functional differentiation among certain insect a-amylases concerning mammalian counterparts and their interactions with different proteinaceous alpha-AIs. Major conclusions: Insect alpha-amylases have conserved domain architecture with differences in length, number of disulfide bonds, and secondary structure. Furthermore, few of them exhibit variable characteristics like chloride dependent activity, the presence of N-terminal glutamine residue to protect against proteolytic degradation, and loop variations near the enzyme active site. Conformation of alpha-AI protein could be an essential factor for their specificity and binding affinities towards target alpha-amylase(s). Furthermore, variation into the enzyme binding pocket residues might contribute to differential interactions with inhibitors. General significance: Molecular insights in the interactions between insect alpha-amylases and plant alpha-AI will provide the details of mechanisms assisting the inhibitor specificity. Furthermore, this information will help to design potent and effective alpha-AIs against specific alpha-amylase.

10aActive site10aalpha-amylase10aalpha-amylase inhibitor10aInsect10amolecular interactions1 aRane, Ashwini, S.1 aJoshi, Rakesh, S.1 aGiri, Ashok, P. uhttps://library.ncl.res.in/content/molecular-determinant-specificity-differential-interaction-alpha-amylases-their02489nas a2200241 4500008004100000022001400041245010400055210006900159260000800228300001400236490000800250520167700258653001801935653002801953653001801981653001501999653001702014100002202031700002102053700002202074700002002096856013102116 2020 eng d a0141-813000aMolecular investigation of coleopteran specific alpha-amylase inhibitors from amaranthaceae members0 aMolecular investigation of coleopteran specific alphaamylase inh cNOV a1444-14500 v1633 a

alpha-Amylase inhibitors (alpha-AIs) target alpha-amylases and interfere with the carbohydrate digestion of insects. Among different classes of alpha-AIs, a knottin-type inhibitor from Amaranthus hypochondriacus (AhAI) was found to be specific against coleopteran storage pests. In this report, we have characterized three previously unidentified knottin-type alpha-AIs from various Amaranthaceae plants namely, Amaranthus hypochondriacus (AhAI2), Alternanthera sessilis (AsAI) and Chenopodium quinoa (CqAI). They contain a signal peptide, pro-peptide, and mature peptide. The mature peptides of the new alpha-AIs shared 68 to 78% identity with AhAI and have highly variable pro-peptide regions. Along with the cystine-knot fold, they showed conservation of reactive site residues. All recombinant alpha-AIs were successfully expressed in their active form and native state using an oxidative cytoplasmic environment. Inhibition studies against various amylases revealed that these inhibitors showed selective inhibition of coleopteran recombinant insect alpha-amylases viz., Tribolium castaneum, and Callosobruchus chinensis. Tribolium castaneum alpha-amylase inhibition potency was highest for AhAI2 (Ki similar to 15 mu M) followed by AsAI (Ki similar to 43 mu M) and CqAI (Ki similar to 61 mu M). Interaction analysis of these inhibitors illustrated that the reactive site of inhibitors make several non-covalent interactions with the substrate-binding pocket of coleopteran alpha-amylases. The selectivity of these inhibitors against coleopteran a-amylases highlights their potential in storage grain pest control. (C) 2020 Elsevier B.V. All rights reserved.

10aalpha-amylase10aalpha-amylase inhibitor10aAmaranthaceae10aColeoptera10aKnottin-type1 aRane, Ashwini, S.1 aVenkatesh, Varun1 aJoshi, Rakesh, S.1 aGiri, Ashok, P. uhttps://library.ncl.res.in/content/molecular-investigation-coleopteran-specific-alpha-amylase-inhibitors-amaranthaceae-members