1v07
From Proteopedia
| Line 4: | Line 4: | ||
==Overview== | ==Overview== | ||
| - | The mini-hemoglobin from Cerebratulus lacteus (CerHb) belongs to a class | + | 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== | ==About this Structure== | ||
| Line 21: | Line 21: | ||
[[Category: Moens, L.]] | [[Category: Moens, L.]] | ||
[[Category: Nardini, M.]] | [[Category: Nardini, M.]] | ||
| - | [[Category: Nienhaus, G | + | [[Category: Nienhaus, G U.]] |
[[Category: Nienhaus, K.]] | [[Category: Nienhaus, K.]] | ||
| - | [[Category: Olson, J | + | [[Category: Olson, J S.]] |
[[Category: Pesce, A.]] | [[Category: Pesce, A.]] | ||
[[Category: Riggs, A.]] | [[Category: Riggs, A.]] | ||
| Line 30: | Line 30: | ||
[[Category: SO4]] | [[Category: SO4]] | ||
[[Category: nerve tissue mini-hemoglobin]] | [[Category: nerve tissue mini-hemoglobin]] | ||
| - | [[Category: oxygen affinity of c | + | [[Category: oxygen affinity of c lacteus mini-hemoglobin]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:30:18 2008'' |
Revision as of 13:30, 21 February 2008
|
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 with , and as ligands. Known structural/functional Site: . 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
Page seeded by OCA on Thu Feb 21 15:30:18 2008
Categories: Cerebratulus lacteus | Single protein | Ascenzi, P. | Bolognesi, M. | Deng, P. | Dewilde, S. | Geuens, E. | Hale, A. | Moens, L. | Nardini, M. | Nienhaus, G U. | Nienhaus, K. | Olson, J S. | Pesce, A. | Riggs, A. | HEM | OXY | SO4 | Nerve tissue mini-hemoglobin | Oxygen affinity of c lacteus mini-hemoglobin
