• Marcinkeviciene, Jovita (PI)
  • Friedman, Joel M. (PI)
  • Ash, D. E. (PI)
  • Gerfen, Gary J. (PI)

Project: Research project

Project Details


A series of 2H- and 13C-labeled glutamates were used as substrates for coenzyme B12-dependent glutamate mutase, which equilibrates (S)-glutamate with (2S, 3S)-3-methylasparate. These compounds contained the isotopes at C-2, C-3 or C-4 of the carbon chain: [2-2H], [3-2H2], [4-2H2], [2,3,3,4,4-2H5], [2-13C], [3-13C], and [4-13C]glutamate. Each reaction was monitored by EPR spectroscopy and revealed a similar signal characterized by g'xy=2.1,g'z=1.985 and A'=5.0mT. The interpretation of the spectral data was aided by simulations which gave close agreement with experiment. This approach underpinned the idea of the formation of a radical pair, consisting of cob(II)alamin interacting with an organic radical at a distance of 6.6+/- 0.9A. Comparison of the hyperfine couplings observed with unlabeled glutamate with those from the labeled glutamates enabled a principle contributor to the radical pair to be identiied as the 4-glytamyl radical. These findings support the currently accepted mechanism for the glutamate mutase reaction, i.e. the process is initiated through hydrogen atom abstraction from C-4 of glutamate by the 5'-deoxyadenosyl radical, which is derived by homolysis of the Co-C sigma-bond o the coenzyme B21.
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