1v07

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spinqualitylabelsall models PDB ID 1v07 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
, resolution 1.70Å
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Ligands:	, ,
Resources:	FirstGlance, OCA, PDBsum, RCSB
Coordinates:	save as pdb, mmCIF, xml

CRYSTAL STRUCTURE OF THRE11VAL MUTANT OF THE NERVE TISSUE MINI-HEMOGLOBIN FROM THE NEMERTEAN WORM CEREBRATULUS LACTEUS

Overview

The mini-hemoglobin from Cerebratulus lacteus (CerHb) belongs to a class of globins containing the polar Tyr-B10/Gln-E7 amino acid pair that normally causes low rates of O2 dissociation and ultra-high O2 affinity, which suggest O2 sensing or NO scavenging functions. CerHb, however, has high rates of O2 dissociation (kO2 = 200-600 s(-1)) and moderate O2 affinity (KO2) approximately 1 microm(-1)) as a result of a third polar amino acid in its active site, Thr-E11. When Thr-E11 is replaced by Val, kO2 decreases 1000-fold and KO2 increases 130-fold at pH 7.0, 20 degrees C. The mutation also shifts the stretching frequencies of both heme-bound and photodissociated CO, indicating marked changes of the electrostatic field at the active site. The crystal structure of Thr-E11 --> Val CerHbO2 at 1.70 A resolution is almost identical to that of the wild-type protein (root mean square deviation of 0.12 A). The dramatic functional and spectral effects of the Thr-E11 --> Val mutation are due exclusively to changes in the hydrogen bonding network in the active site. Replacing Thr-E11 with Val "frees" the Tyr-B10 hydroxyl group to rotate toward and donate a strong hydrogen bond to the heme-bound ligand, causing a selective increase in O2 affinity, a decrease of the rate coefficient for O2 dissociation, a 40 cm(-1) decrease in nuCO of heme-bound CO, and an increase in ligand migration toward more remote intermediate sites.

About this Structure

1V07 is a Single protein structure of sequence from Cerebratulus lacteus. Full crystallographic information is available from OCA.

Reference

Thr-E11 regulates O2 affinity in Cerebratulus lacteus mini-hemoglobin., Pesce A, Nardini M, Ascenzi P, Geuens E, Dewilde S, Moens L, Bolognesi M, Riggs AF, Hale A, Deng P, Nienhaus GU, Olson JS, Nienhaus K, J Biol Chem. 2004 Aug 6;279(32):33662-72. Epub 2004 May 25. PMID:15161908

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