Modulation of Protein Function by Exogenous Ligands in Protein Cavities: CO Binding to a Myoglobin Cavity Mutant Containing Unnatural Proximal Ligands†
ABSTRACT: A variety of heterocyclic ligands can be exchanged into the proximal cavity of sperm whale myoglobin mutant H93G, providing a simple method for introduction of the equivalent of unnatural amino acid side chains into a functionally critical location in this protein. These modified proteins...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.552.1615 2023-05-15T18:26:50+02:00 Modulation of Protein Function by Exogenous Ligands in Protein Cavities: CO Binding to a Myoglobin Cavity Mutant Containing Unnatural Proximal Ligands† Sean M. Decatur Gia D. Depillis Steven G. Boxer The Pennsylvania State University CiteSeerX Archives 1995 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.552.1615 http://www.stanford.edu/group/boxer/papers/paper130.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.552.1615 http://www.stanford.edu/group/boxer/papers/paper130.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.stanford.edu/group/boxer/papers/paper130.pdf text 1995 ftciteseerx 2016-01-08T11:36:31Z ABSTRACT: A variety of heterocyclic ligands can be exchanged into the proximal cavity of sperm whale myoglobin mutant H93G, providing a simple method for introduction of the equivalent of unnatural amino acid side chains into a functionally critical location in this protein. These modified proteins bind CO on the distal side. 1H NMR data on H93G(Im)CO, where Im is imidazole, demonstrate that the structure of the distal heme pocket in H93G(Im)CO is very similar to that of wild type; thus, the effects of the proximal ligand’s properties on CO binding can be studied with minimal perturbation of distal pocket structure. The exogenous proximal ligands used in this study include imidazole (Im), 4-methylimidazole (4-MeIm), 4-bromoimidazole (4-BrIm), N-methylimidazole (N-MeIm), pyridine (Pyr), and 3-fluoropyridine (3-FPyr). Substitution of the proximal ligand is found to produce substantial changes in the CO on and off rates, the equilibrium binding constant, and the vibrational stretch frequency of CO. Many of the changes are as large as those reported for distal pocket mutants prepared by site-directed mutagenesis. The ability to systematically vary the nature of the proximal ligand is exploited to test the effects of particular properties of the proximal ligand on CO binding. For example, 4-MeIm and 4-BrIm are similar in size and shape but differ significantly in pKa. The same relationship is true for Pyr and 3-FPyr. By comparison of the IR spectra and CO recombination kinetics of these complexes, the effects of proximal ligand pKa on the Text Sperm whale Unknown |
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description |
ABSTRACT: A variety of heterocyclic ligands can be exchanged into the proximal cavity of sperm whale myoglobin mutant H93G, providing a simple method for introduction of the equivalent of unnatural amino acid side chains into a functionally critical location in this protein. These modified proteins bind CO on the distal side. 1H NMR data on H93G(Im)CO, where Im is imidazole, demonstrate that the structure of the distal heme pocket in H93G(Im)CO is very similar to that of wild type; thus, the effects of the proximal ligand’s properties on CO binding can be studied with minimal perturbation of distal pocket structure. The exogenous proximal ligands used in this study include imidazole (Im), 4-methylimidazole (4-MeIm), 4-bromoimidazole (4-BrIm), N-methylimidazole (N-MeIm), pyridine (Pyr), and 3-fluoropyridine (3-FPyr). Substitution of the proximal ligand is found to produce substantial changes in the CO on and off rates, the equilibrium binding constant, and the vibrational stretch frequency of CO. Many of the changes are as large as those reported for distal pocket mutants prepared by site-directed mutagenesis. The ability to systematically vary the nature of the proximal ligand is exploited to test the effects of particular properties of the proximal ligand on CO binding. For example, 4-MeIm and 4-BrIm are similar in size and shape but differ significantly in pKa. The same relationship is true for Pyr and 3-FPyr. By comparison of the IR spectra and CO recombination kinetics of these complexes, the effects of proximal ligand pKa on the |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Sean M. Decatur Gia D. Depillis Steven G. Boxer |
spellingShingle |
Sean M. Decatur Gia D. Depillis Steven G. Boxer Modulation of Protein Function by Exogenous Ligands in Protein Cavities: CO Binding to a Myoglobin Cavity Mutant Containing Unnatural Proximal Ligands† |
author_facet |
Sean M. Decatur Gia D. Depillis Steven G. Boxer |
author_sort |
Sean M. Decatur |
title |
Modulation of Protein Function by Exogenous Ligands in Protein Cavities: CO Binding to a Myoglobin Cavity Mutant Containing Unnatural Proximal Ligands† |
title_short |
Modulation of Protein Function by Exogenous Ligands in Protein Cavities: CO Binding to a Myoglobin Cavity Mutant Containing Unnatural Proximal Ligands† |
title_full |
Modulation of Protein Function by Exogenous Ligands in Protein Cavities: CO Binding to a Myoglobin Cavity Mutant Containing Unnatural Proximal Ligands† |
title_fullStr |
Modulation of Protein Function by Exogenous Ligands in Protein Cavities: CO Binding to a Myoglobin Cavity Mutant Containing Unnatural Proximal Ligands† |
title_full_unstemmed |
Modulation of Protein Function by Exogenous Ligands in Protein Cavities: CO Binding to a Myoglobin Cavity Mutant Containing Unnatural Proximal Ligands† |
title_sort |
modulation of protein function by exogenous ligands in protein cavities: co binding to a myoglobin cavity mutant containing unnatural proximal ligands† |
publishDate |
1995 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.552.1615 http://www.stanford.edu/group/boxer/papers/paper130.pdf |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_source |
http://www.stanford.edu/group/boxer/papers/paper130.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.552.1615 http://www.stanford.edu/group/boxer/papers/paper130.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
_version_ |
1766208803831808000 |