Chemical reactivity of Synechococcus sp. PCC 7002 and Synechocystis sp. PCC 6803 hemoglobins: covalent heme attachment and bishistidine coordination
| Autor: | Matthew P. Pond, Emily M. Adney, Matthew R. Preimesberger, Juliette T. J. Lecomte, Benjamin Y. Winer, Henry J. Nothnagel |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Models
Molecular macromolecular substances Heme Biochemistry Article Inorganic Chemistry chemistry.chemical_compound Hemoglobins Histidine Globin Nuclear Magnetic Resonance Biomolecular Synechococcus biology Molecular Structure Electrophilic addition Ligand Synechocystis Hydrogen Peroxide biology.organism_classification chemistry Covalent bond Cysteine |
| Zdroj: | Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry. 16(4) |
| ISSN: | 1432-1327 |
| Popis: | In the absence of an exogenous ligand, the hemoglobins from the cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002 coordinate the heme group with two axial histidines (His46 and His70). These globins also form a covalent linkage between the heme 2-vinyl substituent and His117. The in vitro mechanism of heme attachment to His117 was examined with a combination of site-directed mutagenesis, NMR spectroscopy, and optical spectroscopy. The results supported an electrophilic addition with vinyl protonation being the rate-determining step. Replacement of His117 with a cysteine demonstrated that the reaction could occur with an alternative nucleophile. His46 (distal histidine) was implicated in the specificity of the reaction for the 2-vinyl group as well as protection of the protein from oxidative damage caused by exposure to exogenous H(2)O(2). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full text from SpringerLink