01772nas a2200217 4500008004100000022001400041245014500055210006900200260009900269300001200368490000800380520088800388653002201276653002701298653002101325653002701346653001801373100001801391700001401409856013101423 2012 eng d a0960-852400aInhibition of xyloglucanase from an alkalothermophilic thermomonospora sp by a peptidic aspartic protease inhibitor from Penicillium sp VM240 aInhibition of xyloglucanase from an alkalothermophilic thermomon aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcNOV a390-3990 v1233 a

A bifunctional inhibitor from Penicilliurn sp VM24 causing inactivation of xyloglucanase from Thermomonospora sp and an aspartic protease from Aspergillus saitoi was identified. Steady state kinetics studies of xyloglucanase and the inhibitor revealed an irreversible, non-competitive, two-step inhibition mechanism with IC50 and K-i; values of 780 and 500 nM respectively. The interaction of o-phthalaldehyde (OPTA)-labeled xyloglucanase with the inhibitor revealed that the inhibitor binds to the active site of the enzyme. Far- and near-UV spectrophotometric analysis suggests that the conformational changes induced in xyloglucanase by the inhibitor may be due to irreversible denaturation of enzyme. The bifunctional inhibitor may have potential as a biocontrol agent for the protection of plants against phytopathogenic fungi. (C) 2012 Elsevier Ltd. All rights reserved.

10aAspartic protease10aBifunctional inhibitor10aBiocontrol agent10aInactivation mechanism10aXyloglucanase1 aMenon, Vishnu1 aRao, Mala uhttps://library.ncl.res.in/content/inhibition-xyloglucanase-alkalothermophilic-thermomonospora-sp-peptidic-aspartic-protease-002035nas a2200229 4500008004100000022001400041245012600055210006900181260007500250300001200325490000700337520117600344653002701520653001601547653002001563653002701583653001401610653002301624100001801647700001401665856012601679 2013 eng d a1053-050900aMechanistic insights into the inhibition of endo-beta 1,4 xyloglucan hydrolase by a classical aspartic protease inhibitor0 aMechanistic insights into the inhibition of endobeta 14 xylogluc a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGER/PLENUM PUBLISHERScMAR a311-3210 v233 a

This is the first report of inactivation of xyloglucanase from Thermomonospora sp by pepstatin A, a specific inhibitor towards aspartic proteases. The steady state kinetics revealed a reversible, competitive, two-step inhibition mechanism with IC (50) and K (i) values of 3.5 +/- 0.5 mu M and 1.25 +/- 0.5 mu M respectively. The rate constants determined for the isomerization of EI to EI* and the dissociation of EI* were 14.5 +/- 1.5 x 10(-5) s(-1) and 2.85 +/- 1.2 x 10(-8) s(-1) respectively, whereas the overall inhibition constant K (i) (*) was 27 +/- 1 nM. The conformational changes induced upon inhibitor binding to xyloglucanase were monitored by fluorescence analysis and the rate constants derived were in agreement with the kinetic data. The abolished isoindole fluorescence of o-phthalaldehyde (OPTA)-labeled xyloglucanase and far UV analysis suggested that pepstatin binds to the active site of the enzyme. Our results revealed that the inactivation of xyloglucanase is due to the interference in the electronic microenvironment and disruption of the hydrogen-bonding network between the essential histidine and other residues involved in catalysis.

10a4 xyloglucan hydrolase10aEndo-beta 110aEnzyme kinetics10aInactivation mechanism10aPepstatin10aSlow-tight binding1 aMenon, Vishnu1 aRao, Mala uhttps://library.ncl.res.in/content/mechanistic-insights-inhibition-endo-beta-14-xyloglucan-hydrolase-classical-aspartic-002145nas a2200217 4500008004100000022001400041245014700055210006900202260007900271300001400350490000800364520126400372653002101636653002601657653002701683653003401710653002601744100001801770700001401788856012501802 2014 eng d a0273-228900aInteractions of a low molecular weight inhibitor from streptomyces sp. MBR04 with human cathepsin D: implications in mechanism of inactivation0 aInteractions of a low molecular weight inhibitor from streptomyc a999 RIVERVIEW DRIVE SUITE 208, TOTOWA, NJ 07512 USAbHUMANA PRESS INCcNOV a1705-17230 v1743 a

Cathepsin D, a lysosomal aspartic protease, is of potential interest as a target for drug design due to its implication in breast and ovarian cancer. The article reports a low molecular weight cathepsin D inhibitor from Streptomyces sp. MBR04. The M-r of the inhibitor was 1,078 Da as determined by MALDI-TOF, and the amino acid analysis showed the presence of Asp, Asp, Gly, Ala, Lys, Leu, Tyr, Trp residues. The steady-state kinetic interactions revealed reversible, competitive, slow-tight-binding nature of the inhibitor with an IC50 and K (i) values of 3.2 and 2.5 nM, respectively. The binding of the inhibitor with the enzyme and the subsequent conformational changes were monitored by exploiting the intrinsic fluorescence of the surface exposed Trp-54 residue. Based on the fluorescence and circular dichroism studies, we demonstrate that the inhibitor binds to the active site of cathepsin D and causes inactivation. All these kinetic, thermodynamic, and quenching studies suggest that the newly isolated peptidic inhibitor could be a potential scaffold to study and can be used to develop new potent therapeutic lead molecule for the development of drugs. The inhibitor will be significant as a potential lead molecule to target cathepsin D.

10aCancer treatment10aCathepsin D inhibitor10aInactivation mechanism10aSlow-tight-binding inhibition10aStreptomyces sp MBR041 aMenon, Vishnu1 aRao, Mala uhttps://library.ncl.res.in/content/interactions-low-molecular-weight-inhibitor-streptomyces-sp-mbr04-human-cathepsin-d-0