Fred K. Friedman, Ph.D.

Center for Cancer Research, National Cancer Institute, National Institutes of Health

fkfried@helix.nih.gov

Fred K. Friedman received his Ph.D. degree in chemistry from Columbia University in New York in 1979, where he studied immunoglobulin assembly and antibody-hapten interactions. He joined the Laboratory of Chemical Biology, NIADDK for a three year postdoctoral fellowship in the area of hemoglobin chemistry. He joined NCI in 1982, where his research centers on structure, function and regulation of cytochrome P450. He is currently Chief of the Metabolic Control Section in the Laboratory of Metabolism.

RESEARCH

Structure-function of Cytochrome P450: The multiple forms of cytochrome P450 metabolize a wide variety of xenobiotic compounds such as drugs and carcinogens, as well as endobiotics such as prostaglandins and steroids. Biochemical, biophysical and computational approaches are applied to examine the interactions of P450s with substrates, inhibitors, membrane lipids and microsomal proteins. Since these interactions modulate P450 activity, elucidation of their molecular mechanism will aid in a) clarifying the mechanism of P450 mediated drug and carcinogen metabolism, b) defining the role of individual P450s in the metabolism of endogenous and environmental chemicals and c) development of specific P450 inhibitors.

Rapid kinetic probes of P450 dynamics: The CO flash photolysis technique is applied to study the binding kinetics of CO ligand to P450. This unique probe of P450 conformation/dynamics can be used to define fundamental P450-ligand and P450-substrate interactions in a biological membrane. The kinetics are thus sensitive to binding of substrates and inhibitors, which can sterically hinder CO binding and/or accelerate CO binding via conformational effects. Experiments with human P450s 1A1 and 3A4 show that these are not kinetically homogeneous but are composed of species with different conformations and substrate specificities. In contrast, the alcohol inducible P450 2E1 is homogeneous.

Molecular modeling of P450s: Homology models were generated for rat P450 2B1 and human P450 1A2. The proposed structures include a hydrophobic membrane attachment domain and active sites which are consistent with the known substrate and inhibitor specificities of these P450s. Models were also used to predict the P450 recognition sites for the electron carrier NADPH cytochrome P450 reductase. Synthetic peptides corresponding to these regions on P450 2B1 were prepared and assessed for their ability to inhibit the P450-reductase interaction. The most potent peptide inhibitors were derived from combinations of P450 sequences that are proximate in tertiary structure but distant in primary sequence. Peptide mimics of the P450 surface were thus used to identify a reductase binding domain and thus confirm a predicted feature of the P450 model.

Protein structure-function Using approaches similar to those employed for P450s, functionally important regions on ras-p21 and p53 proteins are identified in collaborations with Drs. M. Pincus (VA and SUNY, Brooklyn NY) and P. Brandt-Rauf (Columbia University). In addition, the laser flash photolysis technique is applied to examine genetically engineered natural and modified hemoglobins, in collaboration with Dr. C. Fronticelli (Johns Hopkins University).

Model of rat P450 2B1, showing mode of membrane attachment

P450 model, showing membrane attachment
 
 

P450 domains

 

Representative Publications:
 
  1. Koley, A.P., Robinson, R.C. and Friedman, F.K: Cytochrome P450 conformationand substrate interactions as probed by CO binding kinetics. Biochimie 78: 706- 713, 1996.
  2. Adler, V., Pincus, M.R., Polotskaya, A., Montano, X., Friedman, F.K. and Ronai, Z.: Activation of C-jun-NH2-kinase by UV-irradiation is dependent on p21ras. J Biol Chem 38:23304-23309, 1996.
  3. Koley, A.P., Dai, R., Robinson, R.C., Markowitz, A. and Friedman, F.K: Interaction of erythromycin with cytochromes P450 3A1/2 in the endoplasmic reticulum: a CO flash photolysis study. Biochemistry 36: 3237-3241, 1997.
  4. Koley, A.P., Buters, J.T.M., Robinson, R.C., Markowitz, A. and Friedman, F.K.: Differential mechanisms of cytochrome P450 inhibition and activation by alpha-naphthoflavone. J Biol Chem 272: 3149-3153, 1997.
  5. Sanna, M.T., Razynska, A., Karavitis, M., Koley, A.P., Friedman, F.K., Russu, I.M., Brinigar, W.S. and Fronticelli, C.: Assembly of human hemoglobin: studies with Escherichia coli expressed alpha-globin. J Biol Chem 272: 3478-3486, 1997.
  6. Amar, S., Glozman, A., Chung, D., Adler, V., Ronai, Z., Friedman, F.K., Robinson, R., Brandt-Rauf, P.W., Yamaizumi, Z. and Pincus, M.R.: Selective inhibition of oncogenic ras-p21 in vivo by agents that block its interaction with jun-N-kinase(JNK) and jun proteins. Implications for the design of selective chemotherapeutic agents. Cancer Chemother Pharmacol 41:79-85, 1997.
  7. Dai, R., Pincus, M.R. and Friedman, F.K.: Molecular modeling of cytochrome P450 2B1: mode of membrane insertion and substrate binding. J Prot Chem17: 121-129, 1998.
  8. Dai, R., Zhai, S., Vestal, R.E. and Friedman, F.K.: Inhibition of human cytochrome P450 1A2 by flavones: a molecular modeling study. J Prot Chem 17: 643-650, 1998.
  9. Zhai, S., Dai, R., Friedman, F.K. and Vestal, R.E.: Comparative inhibition of human cytochromes P450 1A1 and 1A2 by flavonoids. Drug Metabol Disp 26: 989-992, 1998.
  10. Wei, X., Dai, R. Zhai, S., Thummel, K.E., Friedman, F.K. and Vestal, R.E.: Inhibition of human cytochrome CYP 1A2 by the class 1B antiarrhythmics mexiletine, lidocaine, and tocainide. J Pharmacol Exper Ther 289: 853-858, 1999.
  11. Pincus, M.R., Brandt-Rauf, P.W., Michl, J., Carty, RP and Friedman, F.K.: ras-p21-induced cell transformation: unique signal transduction pathways and implications for the design of new chemotherapeutic agents. Cancer Invest 18: 39-50, 2000.
  12. Dai, R., Pincus, M.R. and Friedman, F.K.: Molecular modeling of cytochrome P450. Cell Mol Life Sci 57:487-499, 2000.
  13. Smith, S.V., Koley, A.P., Dai, R., Robinson,R.C., Leong, H., Markowitz, A. and Friedman, F.K.: Conformational Modulation of Human Cytochrome P450 2E1 by Ethanol and Other Substrates: A CO Flash Photolysis Study. Biochemistry 39: 5731-5737, 2000.
  14. Chie, L., Amar, S., Chung, D., Friedman, F.K., Robinson, R.C., Adler, V., Ronai, Z., Kovac, C., Brandt-Rauf, P.W., Yamaizumi,Z., Michl, J. and Pincus, M.R.,: Induction of oocyte maturation by jun-N terminalkinase (JNK) on the oncogenic ras-p21 pathway is dependent on the raf-MEK signal transduction pathway. Cancer Chemother Pharmacol 45: 441-449, 2000.
  15. Omata, Y., Dai, R., Smith, S.V., Robinson, R.C. and Friedman, F.K.: Synthetic Peptide Mimics of a Predicted Topographical Interaction Surface: the Cytochrome P450 2B1 Recognition Domain for NADPH-Cytochrome P450 Reductase. J Prot Chem 19: 23-31, 2000.
  16. Chen, J.M., Rijhwani, K., Friedman, F.K., Hyde, M.J. and Pincus, M.R.: Identification, using molecular dynamics, of an effector domain of the ras-binding domain of the raf-p74 protein that is uniquely involved in oncogenic ras-p21 signaling. J Protein Chem 19: 545-551, 2000.
  17. Ranginwale, M., Smith, S.V., Flom, J., Chie, L., Kanovsky, M., Chung, D., Friedman, F.K., Robinson, R.C., Brandt-Rauf, P.W., Yamaizumi, Z., Michl, J. and Pincus, M.R.: Differences in Patterns of Activation of MAP Kinases Induced by Oncogenic ras-p21 and Insulin in Oocytes. Exper Cell Res 269: 162-169, 2001.
  18. Piro, M.C., Militello, V., Leone, M., Gryczynski, Z., Smith, S.V., Brinigar, W.S., Cupane, A.,  Friedman, F.K. and Fronticelli, C.: Heme pocket disorder in myoglobin: reversal by acid-induced soft refolding. Biochemistry 40: 11841-11850, 2001.
  19. Kovac, C., Chie, L., Morin, J., Friedman, F.K., Robinson, R., Chung, D.L., Kanovsky, M., Flom, J., Brandt-Rauf, P.W., Yamaizumi, Z., Michl, J. and Pincus, M.R.: Plasmid expression of a peptide that selectively blocks oncogenic ras-p21-induced oocyte maturation. Cancer Chemother Pharmacol 48: 9-14, 2001.
  20. Kanovsky, M., Raffo, A., Drew, L., Rosal, R., Do, T. , Friedman, F.K., Rubinstein, P., Visser, J., Robinson, R., Brandt-Rauf, P.W., Michl, J., Fine, R. and Pincus, M.R.: Peptides from the amino terminal MDM2 binding domain of p53, designed from conformational analysis, are selectively cytotoxic to transformed cells. Proc Nat Acad Sci USA 98:12438-12443, 2001.
  21. Hadjokas, N.E., Dai, R., Friedman, F.K., Spence, M.J., Cusack, B.J., Vestal, R.E. and Ma, Y.: Arginine to lysine 108 substitution in recombinant CYP1A2 abolishes methoxyresorufin metabolism in lymphoblastoid cells. Br J Pharmacol 136: 347-352, 2002.
  22. Chen, J.M., Friedman, F.K., Brandt-Rauf, P. Pincus, M.R. and Chie, L.: Comparison of the average structures, from molecular dynamics, of complexes of GTPase Activating Protein (GAP) with oncogenic and wild-type ras-p21: identifification of potential effector domains. J Prot Chem 21:349-359, 2002.
  23. Friedman, F.K., Chie, L., Chung, D., Robinson, R., Brandt-Rauf, P., Yamaizumi, Z. and Pincus, M.R.: Inhibition of ras-induced oocyte maturation by peptides from ras-p21 and GTPase Activating Protein (GAP) identified as effector domains from molecular dynamics calculations. J Prot Chem 21:361-366, 2002.
  24. Chie, L., Friedman, F.K., Kung, H.-F., Lin, M.C.M., Chung, D. and Pincus, M.R.: Identification of the site of inhibition of mitogenic signaling by oncogenic ras-p21 by a ras effector peptide. J Prot Chem 21:367-370, 2002.

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National Library of Medicine On-Line Publication List (with abstracts)

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Last revised on September 18, 2002 by Fred K. Friedman

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