Protonation behavior of histidine 24 and histidine 119 in forming the pH 4 folding intermediate of apomyoglobin. Biochemistry 37:4254–4265
ABSTRACT: Heteronuclear NMR methods are used to study the protonation of histidine and aspartate residues in the acid-induced unfolding of recombinant sperm whale apomyoglobin. The results are combined with fluorescence and circular dichroism measurements of acid-induced unfolding of wild-type and d...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.664.2854 2023-05-15T18:26:49+02:00 Protonation behavior of histidine 24 and histidine 119 in forming the pH 4 folding intermediate of apomyoglobin. Biochemistry 37:4254–4265 Bernhard Geierstanger Marc Jamin Brian F. Volkman Robert L. Baldwin The Pennsylvania State University CiteSeerX Archives 1998 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.664.2854 http://rbaldwin.stanford.edu/PDFs/protonation_behavior_of_histidine.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.664.2854 http://rbaldwin.stanford.edu/PDFs/protonation_behavior_of_histidine.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://rbaldwin.stanford.edu/PDFs/protonation_behavior_of_histidine.pdf text 1998 ftciteseerx 2016-01-08T17:01:20Z ABSTRACT: Heteronuclear NMR methods are used to study the protonation of histidine and aspartate residues in the acid-induced unfolding of recombinant sperm whale apomyoglobin. The results are combined with fluorescence and circular dichroism measurements of acid-induced unfolding of wild-type and double mutant (H24V/H119F) proteins. They are consistent with a simple model in which the failure to protonate a single buried histidine, H24, is largely responsible for the partial unfolding of native (N) wild-type apomyoglobin to the pH 4 folding intermediate (I). H24 is known to form an unusual interaction in which its side chain is buried and hydrogen-bonded to the side chain of H119. Two-dimensional 1H-15N heteronuclear NMR spectra indicate that H24 is present in the rare ä tautomeric form and remains neutral until N unfolds to I, while H119 becomes protonated before the N f I reaction occurs. In the H24V/H119F double mutant, all histidines are protonated in N and the N f I reaction occurs at lower pH. Therefore, the protonation of aspartate and/or glutamate residues must provide an additional driving force for the N to I reaction. Two-dimensional 1H-13C NMR experiments are used to measure the protonation of aspartates in selectively 13C-labeled apomyoglobin; the results indicate that none of the aspartate residues has a strongly depressed pKa in N, as would be expected if it forms a stabilizing salt bridge. Text Sperm whale Unknown |
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ABSTRACT: Heteronuclear NMR methods are used to study the protonation of histidine and aspartate residues in the acid-induced unfolding of recombinant sperm whale apomyoglobin. The results are combined with fluorescence and circular dichroism measurements of acid-induced unfolding of wild-type and double mutant (H24V/H119F) proteins. They are consistent with a simple model in which the failure to protonate a single buried histidine, H24, is largely responsible for the partial unfolding of native (N) wild-type apomyoglobin to the pH 4 folding intermediate (I). H24 is known to form an unusual interaction in which its side chain is buried and hydrogen-bonded to the side chain of H119. Two-dimensional 1H-15N heteronuclear NMR spectra indicate that H24 is present in the rare ä tautomeric form and remains neutral until N unfolds to I, while H119 becomes protonated before the N f I reaction occurs. In the H24V/H119F double mutant, all histidines are protonated in N and the N f I reaction occurs at lower pH. Therefore, the protonation of aspartate and/or glutamate residues must provide an additional driving force for the N to I reaction. Two-dimensional 1H-13C NMR experiments are used to measure the protonation of aspartates in selectively 13C-labeled apomyoglobin; the results indicate that none of the aspartate residues has a strongly depressed pKa in N, as would be expected if it forms a stabilizing salt bridge. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Bernhard Geierstanger Marc Jamin Brian F. Volkman Robert L. Baldwin |
spellingShingle |
Bernhard Geierstanger Marc Jamin Brian F. Volkman Robert L. Baldwin Protonation behavior of histidine 24 and histidine 119 in forming the pH 4 folding intermediate of apomyoglobin. Biochemistry 37:4254–4265 |
author_facet |
Bernhard Geierstanger Marc Jamin Brian F. Volkman Robert L. Baldwin |
author_sort |
Bernhard Geierstanger |
title |
Protonation behavior of histidine 24 and histidine 119 in forming the pH 4 folding intermediate of apomyoglobin. Biochemistry 37:4254–4265 |
title_short |
Protonation behavior of histidine 24 and histidine 119 in forming the pH 4 folding intermediate of apomyoglobin. Biochemistry 37:4254–4265 |
title_full |
Protonation behavior of histidine 24 and histidine 119 in forming the pH 4 folding intermediate of apomyoglobin. Biochemistry 37:4254–4265 |
title_fullStr |
Protonation behavior of histidine 24 and histidine 119 in forming the pH 4 folding intermediate of apomyoglobin. Biochemistry 37:4254–4265 |
title_full_unstemmed |
Protonation behavior of histidine 24 and histidine 119 in forming the pH 4 folding intermediate of apomyoglobin. Biochemistry 37:4254–4265 |
title_sort |
protonation behavior of histidine 24 and histidine 119 in forming the ph 4 folding intermediate of apomyoglobin. biochemistry 37:4254–4265 |
publishDate |
1998 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.664.2854 http://rbaldwin.stanford.edu/PDFs/protonation_behavior_of_histidine.pdf |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_source |
http://rbaldwin.stanford.edu/PDFs/protonation_behavior_of_histidine.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.664.2854 http://rbaldwin.stanford.edu/PDFs/protonation_behavior_of_histidine.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
_version_ |
1766208792887820288 |