1999
DOI: 10.1021/bi9908888
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Hydrogen Bonding Modulates Binding of Exogenous Ligands in a Myoglobin Proximal Cavity Mutant

Abstract: In the sperm whale myoglobin mutant H93G, the proximal histidine is replaced by glycine, leaving a cavity in which exogenous imidazole can bind and ligate the heme iron (Barrick, D. (1994) Biochemistry 33, 6545-6554). Structural studies of this mutant suggest that serine 92 may play an important role in imidazole binding by serving as a hydrogen bond acceptor. Serine 92 is highly conserved in myoglobins, forming a well-characterized weak hydrogen bond with the proximal histidine in the native protein. We have… Show more

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Cited by 31 publications
(43 citation statements)
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“…The relative thermodynamic stability of the ligands in the proximal pocket has been determined [29]. The increased relative stability of imidazole and 4-methyl imidazole ligands over the 1-methyl and 2-methyl imidazoles is likely due to the fact that the first two species are closest in binding geometry to the wild-type histidine side-chain.…”
Section: Discussionmentioning
confidence: 99%
See 1 more Smart Citation
“…The relative thermodynamic stability of the ligands in the proximal pocket has been determined [29]. The increased relative stability of imidazole and 4-methyl imidazole ligands over the 1-methyl and 2-methyl imidazoles is likely due to the fact that the first two species are closest in binding geometry to the wild-type histidine side-chain.…”
Section: Discussionmentioning
confidence: 99%
“…Nonetheless, there is a substantial difference in the proximal dynamics for these two ligands. It is reasonable to suggest that the inability of 1-methyl imidazole to form a hydrogen bond is responsible for the differences in proximal dynamics [29]. Comparison with other proximal mutations such as S92A and L89I indicates that hydrogen bonding does not have a large effect when native histidine is ligated to the heme iron [45].…”
Section: H93g(1-meim) Probes Hydrogen Bonding In the Proximal Pocketmentioning
confidence: 99%
“…The proximal histidine in Mb is H-bonded to Ser92, a highly conserved residue [50]. Very recently, this H-bond interaction was determined to be very important in modulating the ligand binding affinity of the heme iron when the bonding between the iron and the proximal ligand are weak, conditions similar to those that characterize Mb in DMSO [51]. An alternative mechanism involves the protonation of the N atom of the proximal histidine and consequent cleavage of the Fe-N bond.…”
Section: Heme Active Site Structural Alterationsmentioning
confidence: 95%
“…In the case of monomeric hemoproteins, the protein matrix plays important roles through residues that either limit the access of the ligand to the distal portion of the heme pocket (3)(4)(5)(6) or constrain the conformation of the hemoprotein stereochemistry in the proximal portion of the pocket (7)(8)(9). In the case of myoglobin, the H-bond between Ser 92 and N ␦ of the proximal His 93 appears to be of particular importance (9).…”
mentioning
confidence: 99%
“…In the case of myoglobin, the H-bond between Ser 92 and N ␦ of the proximal His 93 appears to be of particular importance (9).…”
mentioning
confidence: 99%