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rdf:type |
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lifeskim:mentions |
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pubmed:dateCreated |
1997-6-3
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pubmed:abstractText |
The stability and activity of indole-3-glycerol phosphate synthase from Sulfolobus solfataricus were studied as a function of pH and temperature. In this paper we focus on three points: (1) the long-term stability of the protein to irreversible denaturation at high temperature; (2) the short-term stability of the protein to reversible temperature-driven unfolding; and (3) the dependence of its activity on temperature. Results can be summarized as follows: (a) the same first-order kinetic constant (0.020+/-0.003 min-1) was determined at different pH values (6.5, 8.0 and 9.5) from long-term stability experiments at 80 degrees C; (b) short-term stability experiments revealed different behaviour in two different pH ranges (6.5-8.0, 8.5-9.5), suggesting that the melting temperature is higher at alkaline than at neutral pH; (c) the dependence of activity on temperature was investigated at pH 7.0 and 9.0, and a discontinuity was observed in the Arrhenius plot of kcat values at pH 9.0. We also investigated the stability in the presence of guanidinium chloride at 20 degrees C either at pH 7.0 or at pH 9.0, and we present data that indicate that the unfolding mechanism closely approaches a two-state model at pH 7.0 and a more complex mechanism at pH 9.0. Satisfactory fitting of the equilibrium unfolding transition obtained by fluorescence measurements at pH 9.0 required a model that involves a stable intermediate in addition to the native and unfolded forms. At 20 degrees C the folded conformation is more stable than the unfolded conformation by (14. 7+/-1.2) kJ/mol at pH 7.0 and by (25.5+/-1.8) kJ/mol at pH 9.0.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-1429615,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-1463738,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-1551394,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-3233195,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-3298981,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-3303031,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-3773761,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-4001942,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-4200852,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-4912353,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-4924490,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-4978220,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-5332729,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-5636809,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-5942950,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-7290210,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-7947963,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-8297515,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-8416906,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-8747456,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-881418,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9173891-942051
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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 |
1
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pubmed:volume |
323 ( Pt 1)
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
259-64
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
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pubmed:year |
1997
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pubmed:articleTitle |
Stability of a thermophilic TIM-barrel enzyme: indole-3-glycerol phosphate synthase from the thermophilic archaeon Sulfolobus solfataricus.
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pubmed:affiliation |
Dipartimento di Chimica Organica e Biologica, Via Mezzocannone 16, Universit à di Napoli 'Federico II', 80134 Napoli, Italy.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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