PROTEIN STRUCTURE-FUNCTION RELATIONSHIP

Aromatic amino acids, like other proteinogenic amino acids, are building blocks of proteins. Moreover, they serve as precursors for the synthesis of many neurologically active compounds that are essential for maintaining the normal brain functions in human and other species. For example, tryptophan is the initial precursor for the biosynthesis of tryptamine, serotonin, and melatonin. Kynurenic acid, produced along the tryptophan-kynurenine pathway, is an antagonist at excitatory amino acid receptors and plays a role in protecting neurons from overstimulation by excitatory neurotransmitters. Tyrosine is the initial precursor for the biosynthesis dopa, dopamine, norepinephrine and epinephrine. In addition, tyrosine is the precursor for melanin synthesis.

Our current research includes the determination of the structure-function relationship of proteins involved in kynurenic acid biosynthesis along the tryptophan-kynurenine pathway in the mouse model. Our current studies also include characterization of proteins involved in tyrosine metabolisms in insects and mammals. We have active research collaboration with colleagues at VT in Chemistry and Entomology, at the University of Wisconsin-Madison and at NIH.



Protein structures solved during the past 5 years.

Kajla M.K. Shi L., Li B., Luckhart S., Li J. and Paskewitz S.M. (2011) A new role for an old antimicrobial: Lysozyme c-1 can function to protect malarial parasites in Anopheles mosquitoes. PloS One 6;6(5): e19649. PMID: 21573077   [Abstract]

Vavricka C, Han Q, Huang Y, Erickson SM, Harich K, Christensen BM, Li J. (2011) From L-dopa to 3,4-dihydroxyphenylacetaldehyde: a toxic biochemical pathway plays a vital physiological function. PloS One 24;6:e16124. PMID: 21283636   [Abstract]

Mehere P., Han Q., Christensen B.M. and Li J. (2011) Identification and characterization of two arylalkylamine N-acetyltransferase in the yellow fever mosquito, Aedes aegypti. Insect Biochemistry and Molecular Biology 41: 707-714. PMID: 21645618    [Abstract]

Han Q., Robinson H., Cai T., Tagle D.A. and Li J. (2011) Biochemical and structural characterization of mouse mitochondrial aspartate aminotransferase, a newly identified kynurenine aminotransferase-IV. Bioscience Report 31: 323-332.    [Abstract]

Han Q, Ding H, Robinson H, Christensen BM and Li J (2010) Crystal structure and substrate specificity of Drosophila 3,4-dihydroxyphenylalanine decarboxylase. PloS ONE. Volume 5, Issue 1, e8826.   [Abstract]

Mehere P., Han Q., Lemkul J.A., Robinson H., Bevan D.R. and Li J. (2010) Tyrosine aminotransferase: Biochemical and structural properties and molecular dynamics simulations. Protein & Cell 1: 1023-1032. PMID: 21153519

Han Q., Cai T., Tagle D.A. and Li J. (2010) Thermal stability, pH dependence and inhibition of four murine kynurenine aminotransferases. BMC Biochemistry 11: 19. PMID: 20482848   [Abstract]

Han Q, Cai T, Tagle DA and Li J (2009) Structure, expression and function of kynurenine aminotransferases in human and rodents brains. Cellular and Molecular Life Sciences 67: 353-368 (PMID: 19826765).    [Abstract]

Han Q, Robinson H, Cai T, Tagle DA and Li J (2009). Structural insight into the inhibition of human kynurenine aminotransferase I/glutamine transaminase K. Journal of Medicinal Chemistry 52: 2786 – 2793 (PMID: 19338303)   [Abstract]

Han Q, Robinson H, Cai T, Tagle D and Li J (2009) Biochemical and structural properties of mouse KAT III. Molecular and Cellular Biology 29: 784‐793 (PMID: 19029248).   [Abstract]