2vyy

Mutant Ala55Trp of Cerebratuls lacteus mini-hemoglobin

spinqualitylabelsall models 2vyy, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2vyy is a 1 chain structure with sequence from Cerebratulus lacteus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: GOL, HEM, OXY, SO4 Related: 1v07, 1kr7, 2vyz Resources: FirstGlance, OCA, RCSB, PDBsum Function [GLBN_CERLA] Acts as an oxygen store capable of sustaining neuronal activity in an anoxic environment for 5 to 30 min. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The major pathway for O2 binding to mammalian myoglobins (Mb) and hemoglobins (Hb) involves transient upward movement of the distal histidine (His-64(E7)), allowing ligand capture in the distal pocket. The mini-globin from Cerebratulus lacteus (CerHb) appears to have an alternative pathway between the E and H helices that is made accessible by loss of the N-terminal A helix. To test this pathway, we examined the effects of changing the size of the E7 gate and closing the end of the apolar channel in CerHb by site-directed mutagenesis. Increasing the size of Gln-44(E7) from Ala to Trp causes variation of association (k'O2) and dissociation (kO2) rate coefficients, but the changes are not systematic. More significantly, the fractions (Fgem approximately 0.05-0.19) and rates (kgem approximately 50-100 micros(-1)) of geminate CO recombination in the Gln-44(E7) mutants are all similar. In contrast, blocking the entrance to the apolar channel by increasing the size of Ala-55(E18) to Phe and Trp causes the following: 1) both k'O2 and kO2 to decrease roughly 4-fold; 2) Fgem for CO to increase from approximately 0.05 to 0.45; and 3) kgem to decrease from approximately 80 to approximately 9 micros(-1), as ligands become trapped in the channel. Crystal structures and low temperature Fourier-transform infrared spectra of Phe-55 and Trp-55 CerHb confirm that the aromatic side chains block the channel entrance, with little effect on the distal pocket. These results provide unambiguous experimental proof that diatomic ligands can enter and exit a globin through an interior channel in preference to the more direct E7 pathway. The apolar channel in Cerebratulus lacteus hemoglobin is the route for O2 entry and exit.,Salter MD, Nienhaus K, Nienhaus GU, Dewilde S, Moens L, Pesce A, Nardini M, Bolognesi M, Olson JS J Biol Chem. 2008 Dec 19;283(51):35689-702. Epub 2008 Oct 7. PMID:18840607 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Hemoglobin 3D structures

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