Project: Research project

Project Details


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.
Effective start/end date10/1/959/30/99


  • National Center for Research Resources


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


    Project: Research project