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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
2
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pubmed:dateCreated |
1989-6-20
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pubmed:abstractText |
1. The pH-dependence of the second-order rate constant (k) for the reaction of actinidin (EC 3.4.22.14) with 2-(N'-acetyl-L-phenylalanylamino)ethyl 2'-pyridyl disulphide was determined and the contributions to k of various hydronic states were evaluated. 2. The data were used to assess the consequences for transition-state geometry of providing P2/S2 hydrophobic contacts in addition to hydrogen-bonding opportunities in the S1-S2 intersubsite region. 3. The P2/S2 contacts (a) substantially improve enzyme-ligand binding, (b) greatly enhance the contribution to reactivity of the hydronic state bounded by pKa 3 (the pKa characteristic of the formation of catalytic-site-S-/-ImH+ state) and pKa 5 (a relatively minor contributor in reactions that lack the P2/S2 contacts), such that the major rate optimum occurs at pH 4 instead of at pH 2.8-2.9, and (c) reveal the kinetic influence of a pKa approx. 6.3 not hitherto observed in reactions of actinidin. 4. Possibilities for the interplay of electrostatic effects and binding interactions in both actinidin and papain (EC 3.4.22.2) are discussed.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-11777,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-16744552,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-17874,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-234862,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-25211,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-27512,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-2825655,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-2839145,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-2881845,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-2920023,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-2920024,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-3178748,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-3223929,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-3237687,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-36130,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-3663111,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-3889350,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-4382801,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-4399049,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-444461,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-4692655,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-5084800,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-5126466,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-5466499,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-678536,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-687380,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-7003158,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-7025834,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-7034724,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2719659-743223
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Apr
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pubmed:issn |
0264-6021
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
15
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pubmed:volume |
259
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
443-52
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pubmed:dateRevised |
2010-9-10
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pubmed:meshHeading |
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pubmed:year |
1989
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pubmed:articleTitle |
The interplay of electrostatic fields and binding interactions determining catalytic-site reactivity in actinidin. A possible origin of differences in the behaviour of actinidin and papain.
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pubmed:affiliation |
Department of Biochemistry, Medical College of St. Bartholomew's Hospital (University of London), U.K.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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