EPR OF METHEMOGLOBIN FORMATION IN RED CELLS W/ UNSTABLE HEMOGLOBIN

Project: Research project

Project Details

Description

A Hb from the chloroplast of Chlamydomonas eugametos has been cloned andexpressed in E. coli. This Hb resembles several invetebrate in having a tyr residue in the B10 and a glut in the E7 positions, both of which are believed to participate in H-bonding to bound O2 that results in extremely slow off-rates. On the other hand, Chlamydomonas Hb is unusual in that the ferrous protein has a high-spin to low spin (six-coordinate) transition pK of 8.5, whereas the ferric protein has a high-spin to low spin (six-coordinate) transition pK of 6.4. This suggests that the distal ligand of the low spin forms of the ferrous and the ferric proteins may be different. The ferric protein exhibits a single low spin form with g values of 2.52, 2.31, 1.86, and thus an anisotropy similar to that of myoglobin hydroxide. However, 17O EPR and 18O resonance Raman studies failed to provide direct evidence for a hydroxide ligand. Spectroscopic studies on the distal mutants of the B10 Tyr, E7 Gln, and the E10 Lys residues have so far failed to identify a possible amino acid ligand. Further studies are being conducted to identify the distal ligand and to understand the unusual low spin EPR spectrum.
StatusFinished
Effective start/end date10/1/959/30/99

Funding

  • National Center for Research Resources

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  • BIOTECHNOLOGY RESOURCE IN PULSED EPR SPECTROSCOPY

    Peisach, J., Aisen, P., Armstrong, W. H., Ash, D. E., Astroff, N., Avdievich, N., Baker, T. A., Banerjee, R. V., Bender, C., Benkovic, S., Brewer, C. F., Brewer, F., Britt, D., Cammack, R., Caradonna, J., Chan, J., Colaneri, M., Danzinger, N. R., Das, T., Dooley, D., Dyson, H. J., Ettinger, M., Fabry, M. E., Fee, J. A., Frank, N. H. A., Friedman, J. M., Gerfen, G. J., Goutermann, M., Guajardo, G. B., Janson, E., Kamp, N., Kozarich, J., Lee, C. C., Lippai, I., Magliozzo, R. S., Mason, R., McMillin, D., Michael, D., Mildvan, A., Mims, W. B., Narasimhulu, S., Nersissian, A., Ohnishi, T., Palmer, G., Que, L., Rousseau, D. L., Sam, J., Scholes, C., Scholes, C. P., Schramm, V. L., Shaka, O., Shanklin, J., Sinclair, P., Singel, D., Stafford, D. W., Stegeman, J., Stubbe, N. J. A., Stubbe, J., Tipton, P. A., Villafranca, N. J. J., Walter, P., Wang, W., Wittaker, J., Zweier, J. L., Belford, L., Beltramini, M., Bowman, M., Chance, M., Clarkson, R., Coffino, A., Crowder, M., Gluck, M. R., Klein, M., Klinman, J., Krzystek, Y., Licht, S., Marcinkeviciene, J., Mcdermott, A., Ming, L., Peisach, J., Ranney, H., Sands, R., Sheik, A., Stubbe, J., Sumuni, R., Tsuneshige, A., Valentine, J., Vieso, V., Wirt, M., Wong, K. & Zhang, C.

    9/30/854/30/00

    Project: Research project