Salt effects on ionization equilibria of histidines in myoglobin.
The salt dependence of histidine pK(a) values in sperm whale and horse myoglobin and in histidine-containing peptides was measured by (1)H-NMR spectroscopy. Structure-based pK(a) calculations were performed with continuum methods to test their ability to capture the effects of solution conditions on...
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ftpubmed:oai:pubmedcentral.nih.gov:1301056 2023-05-15T18:26:47+02:00 Salt effects on ionization equilibria of histidines in myoglobin. Kao, Y H Fitch, C A Bhattacharya, S Sarkisian, C J Lecomte, J T García-Moreno E, B 2000-09 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1301056 http://www.ncbi.nlm.nih.gov/pubmed/10969024 en eng http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1301056 http://www.ncbi.nlm.nih.gov/pubmed/10969024 Research Article Text 2000 ftpubmed 2013-08-30T17:56:51Z The salt dependence of histidine pK(a) values in sperm whale and horse myoglobin and in histidine-containing peptides was measured by (1)H-NMR spectroscopy. Structure-based pK(a) calculations were performed with continuum methods to test their ability to capture the effects of solution conditions on pK(a) values. The measured pK(a) of most histidines, whether in the protein or in model compounds, increased by 0.3 pH units or more between 0.02 M and 1.5 M NaCl. In myoglobin two histidines (His(48) and His(36)) exhibited a shallower dependence than the average, and one (His(113)) showed a steeper dependence. The (1)H-NMR data suggested that the salt dependence of histidine pK(a) values in the protein was determined primarily by the preferential stabilization of the charged form of histidine with increasing salt concentrations rather than by screening of electrostatic interactions. The magnitude and salt dependence of interactions between ionizable groups were exaggerated in pK(a) calculations with the finite-difference Poisson-Boltzmann method applied to a static structure, even when the protein interior was treated with arbitrarily high dielectric constants. Improvements in continuum methods for calculating salt effects on pK(a) values will require explicit consideration of the salt dependence of model compound pK(a) values used for reference in the calculations. Text Sperm whale PubMed Central (PMC) |
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Research Article Kao, Y H Fitch, C A Bhattacharya, S Sarkisian, C J Lecomte, J T García-Moreno E, B Salt effects on ionization equilibria of histidines in myoglobin. |
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Research Article |
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The salt dependence of histidine pK(a) values in sperm whale and horse myoglobin and in histidine-containing peptides was measured by (1)H-NMR spectroscopy. Structure-based pK(a) calculations were performed with continuum methods to test their ability to capture the effects of solution conditions on pK(a) values. The measured pK(a) of most histidines, whether in the protein or in model compounds, increased by 0.3 pH units or more between 0.02 M and 1.5 M NaCl. In myoglobin two histidines (His(48) and His(36)) exhibited a shallower dependence than the average, and one (His(113)) showed a steeper dependence. The (1)H-NMR data suggested that the salt dependence of histidine pK(a) values in the protein was determined primarily by the preferential stabilization of the charged form of histidine with increasing salt concentrations rather than by screening of electrostatic interactions. The magnitude and salt dependence of interactions between ionizable groups were exaggerated in pK(a) calculations with the finite-difference Poisson-Boltzmann method applied to a static structure, even when the protein interior was treated with arbitrarily high dielectric constants. Improvements in continuum methods for calculating salt effects on pK(a) values will require explicit consideration of the salt dependence of model compound pK(a) values used for reference in the calculations. |
format |
Text |
author |
Kao, Y H Fitch, C A Bhattacharya, S Sarkisian, C J Lecomte, J T García-Moreno E, B |
author_facet |
Kao, Y H Fitch, C A Bhattacharya, S Sarkisian, C J Lecomte, J T García-Moreno E, B |
author_sort |
Kao, Y H |
title |
Salt effects on ionization equilibria of histidines in myoglobin. |
title_short |
Salt effects on ionization equilibria of histidines in myoglobin. |
title_full |
Salt effects on ionization equilibria of histidines in myoglobin. |
title_fullStr |
Salt effects on ionization equilibria of histidines in myoglobin. |
title_full_unstemmed |
Salt effects on ionization equilibria of histidines in myoglobin. |
title_sort |
salt effects on ionization equilibria of histidines in myoglobin. |
publishDate |
2000 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1301056 http://www.ncbi.nlm.nih.gov/pubmed/10969024 |
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Sperm whale |
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Sperm whale |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1301056 http://www.ncbi.nlm.nih.gov/pubmed/10969024 |
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1766208750433075200 |