Variation in aspects of cysteine proteinase catalytic mechanism deduced by spectroscopic observation of dithioester intermediates, kinetic analysis and molecular dynamics simulations.

@article{Reid2001VariationIA,
  title={Variation in aspects of cysteine proteinase catalytic mechanism deduced by spectroscopic observation of dithioester intermediates, kinetic analysis and molecular dynamics simulations.},
  author={J. D. Reid and S. Hussain and S. Sreedharan and T. S. Bailey and S. Pinitglang and E. Thomas and C. Verma and K. Brocklehurst},
  journal={The Biochemical journal},
  year={2001},
  volume={357 Pt 2},
  pages={
          343-52
        }
}
The possibility of a slow post-acylation conformational change during catalysis by cysteine proteinases was investigated by using a new chromogenic substrate, N-acetyl-Phe-Gly methyl thionoester, four natural variants (papain, caricain, actinidin and ficin), and stopped-flow spectral analysis to monitor the pre-steady state formation of the dithioacylenzyme intermediates and their steady state hydrolysis. The predicted reversibility of acylation was demonstrated kinetically for actinidin and… Expand
Variation in the pH-dependent pre-steady-state and steady-state kinetic characteristics of cysteine-proteinase mechanism: evidence for electrostatic modulation of catalytic-site function by the neighbouring carboxylate anion.
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Differences in the forms of pH-dependence of the steady-state and pre-steady-state kinetic parameters support the hypothesis that, whereas for papain, the rate-determining step is the base-catalysed reaction of the acyl-enzyme intermediate with water, for actinidin it is a post-acylation conformational change required to permit release of the alcohol product and its replacement in the catalytic site by the key water molecule. Expand
Isomerization of the uncomplexed actinidin molecule: kinetic accessibility of additional steps in enzyme catalysis provided by solvent perturbation.
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The free enzyme isomerization of actinidin may provide an explanation for the marked difference in sensitivity between this enzyme and papain of binding site-catalytic site signalling in reactions of substrate-derived 2-pyridyl disulphide reactivity probes. Expand
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Conformational mobility of active and E-64-inhibited actinidin.
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Carbothioic, carboselenoic, and carbotelluroic acids, which have been recognized to exist as tautomeric mixtures of X-acid (X = S, Se, Te) and O-acid forms, were revealed spectroscopically to existExpand
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This up-date reviews papers published between 2003 and 2012. A number of thionolactones such as thionocoumarins and isothionocoumarins have been synthesized from the corresponding lactones withExpand
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Abstract The deacylation reaction of the cysteine protease papain was examined by AM1 reaction-coordinate calculations. The transition-state (TS) structure was extracted from the reaction pathway asExpand
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