Department of Medicinal & Biological Chemistry : James T. Slama

 Institutions/Degrees

Medicinal/pharmaceutical chemistry; organic chemistry. Mechanisms of enzymatic and organic reactions, design of specific mechanism-based enzymye inhibitors, structure and synthesis of natural products of biochemical interest.

Research Interests

The general focus of our research is on glycosidases, glycosyltransferases, nucleosidases, and ADP-ribosyl transferases. Each of these enzyme families defines an important area of research and each offers novel opportunities for new drug development. Glycosidases are important in the digestion of carbohydrates and in the biosynthesis of glycoproteins containing complex carbohydrate chains. Glycosyl transferases utilize nucleoside diphosphate sugars and are responsible for the biosynthesis of complex carbohydrates, glycoproteins, and glycolipids, and in microorganisms for the synthesis of the cell wall. Nucleosidases function in nucleotide and nucleotide salvage pathways targeted by a variety of anticancer, immunosuppressive, and antiprotozoal drugs. Last, ADP-ribosyl transferases catalyze transfer of the ADP-ribose moiety of NAD to a variety of macromolecular acceptors. The functions of ADP-ribosyl transfer reactions are poorly understood, but roles in cell regulation seems likely. Compounds that target ADP-ribosyl transfer reactions could therefore constitute a new class of drugs.

Our experimental approach combines efforts directed toward the design and synthesis of mechanism based enzyme inhibitors with biochemical studies on targeted enzymes, utilizing both conventional and recombinant DNA-based approaches. The goal is to better understand the metabolism and biological function of each enzyme family and at the same time define the specific enzymatic targets relevant to drug development.

As an example, some of our recent work focuses on studies on ADP-ribosyl transfer reactions where oxidized nicotinamide adenine dinucleotide (NAD) serves as an adenosine diphosphate ribose (ADP-ribose) donor. CarbaNAD was the first successful designed inhibitor for this class of enzyme. In carbaNAD a cyclopentane ring replaces the furanose of the nicotinamide ribonucleoside moiety. CarbaNAD is therefore resistant to nicotinamide ribotide cleavage but is recognized as a competitive inhibitor by several ADP-ribosyl transferases.

Adenosine diphosphate (hydroxymethyl)pyrrolidinediol (ADP-HPD) is another example of a successful designed inhibitor. ADP-HPD is a nitrogen-in-the-ring analog of ADP-ribose and a potent inhibitor of poly(ADP-ribose) glycohydrolase. Poly(ADP-ribose) glycohydrolase catalyzes the degradation of ADP-ribose polymers, which are synthesized in the nucleus as a response to DNA damage. ADP-HPD will serve as a useful biochemical probe for deciphering the structure and mechanism of this glycohydrolase. It will also be applied in ongoing studies to elucidate the function of ADP-ribose metabolism following DNA damage. Last, it will serve as a lead compound for the development of inhibitors with improved stability and bioavailability, which may be useful as antitumor drugs.

Representative Publications

1. Hatanaka, K., J.T. Slama and A.D. Elbein. Synthesis of new inhibitors of UDP-GalNAc: polypeptide galactosaminyl transferase. Biochem. Biophys. Res. Comm. 175, 668-672,1991.
   
   
2. Slama, J.T. and A.M. Simmons. Synthesis and properties of photoaffinity labels for the pyridine dinucleotide binding site of NAD glycohydrolase. Biochemistry 30, 2527-2534, 1991.
   
   
3. Drake, R.R., J.T. Slama, K.A. Wall, M. Abramova, C. D'Souza, A.D. Elbein, P.J. Crocker and D.S. Watt. Application of an N-(4-azido-2,3,5,6-tetrafluorobenzoyl)-tyrosine-substituted peptide as a heterobifunctional cross-linking agent in a study of protein O-glycosylation in yeast. Bioconjugate Chem. 3, 69-73, 1992.
   
   
4. Goli, D.M., B. Cheeseman, M.E. Hassan, R. Lodaya and J.T. Slama. Synthesis of (2R,3S,4R)-2-hydroxymethylpyrrolidine-3,4-diol from (2S)-3,4-dehydroproline. Carbohydrate Res. 259, 219-241, 1994.
   
   
5. Slama, J.T., N. Aboul-Ela, D.M. Goli, B.V. Cheeseman, A.M. Simmons and M.K. Jacobson. Specific inhibition of poly(ADP-ribose) glycohydrolase by adenosine diphosphate (hydroxymethyl)pyrrolidinediol. J. Med. Chem. 38, 389-393, 1995.
   
   
6. Slama, J.T., N. Aboul-Ela and M. K. Jacobson. Mechanism of inhibition of poly(ADP-ribose) glycohydrolase by adenosine diphosphate (hydroxymethyl)pyrrolidinediol. J. Med. Chem. 38, 4332-4336, 1995.
   
   
7. Mueller-Steffner, H., J. Slama and F. Schuber. Photodependent inhibition of bovine spleen NAD+ glycohydrolase by 8-azido carbocyclic analogs of NAD+. Biochem. Biophys. Res. Comm. 228, 128-133, 1996.
   
   
8. Slama, J.T., J.L. Hancock, T. Rho, L. Sambucetti, and K.A. Bachmann. Influence of Some Novel N-Substituted Azoles and Pyridines on Rat Hepatic CYP3A Activity. Biochemical Pharmacology 55: 1881-1892, 1998.
   
   
9. Ramsinghani, S., D. Coyle, J. Amé, D.W. Koh, M.K. Jacobson and J.T. Slama. Syntheses of Photoactive Analogs of Adenosine Diphosphate (Hydroxymethyl)pyrrolidine Diol and Photoaffinity Labeling of Poly(ADP-ribose) Glycohydrolase. Biochemistry 37: 7801-7812, 1998.
   
   
10. Wall, K.A., M. Klis, J. Kornet, D. Coyle, J. Amé, M.K. Jacobson and J.T. Slama. Inhibition of the Intrinsic NADase Activity of CD38 by Carbocyclic NAD Analogs. Biochemical Journal 335: 631-636, 1998.
    
    
11. Lodaya, R. and J.T. Slama. Synthesis of [a-32P]-8-N3-NAD, A Photoaffinity Labeling Reagent for Pyridine Dinucleotide Binding Sites. Journal of Labelled Compounds and Radiopharmaceuticals, 42: 867-875, 1999.
    
    
12. Rita Lodaya, Steven R. Blanke, R. John Collier and James T. Slama. Photoaffinity Labeling of Diphteria Toxin Fragment A with 8-Azidoadenosy Nicotinamide Adenine Dinucleotide. Biochemistry, 38:13877-13886, 1999.
    
    
13. Tomohiko Maehama, Gregory S. Taylor, James T. Slama, and Jack E. Dixon. "A sensitive Assay for Phosphoinositide Phosphatases" Analytical Biochemistry 279: 248-250, 2000.