Su Chen Li, PhD
Department of Biochemistry and Molecular Biology
Tulane University School of Medicine
1430 Tulane Avenue, #8543
New Orleans, LA, 70112
Glycobiology – Biochemical basis of inborn lysosomal diseases and biomedically useful glycosidases
S.-C. Li and her husband, Y.-T. Li, have been working as a team in the field of glycobiology for over three decades. The two major research projects in the Li's lab are: (i) biochemical studies of inborn lysosomal diseases, and (ii) studies of biomedically useful glycosidases. S.-C. Li is in charge of Project (i) and Y.-T. Li is responsible for Project (ii).
Through the studies of the catabolism of glycoconjugates, the Lis have contributed substantially to the basic understanding of the biochemical basis of Fabry's disease and Tay-Sachs disease. Their laboratory was the first to correctly establish the structure of the glycosphingolipid that accumulates in the kidney of patients with Fabry's disease (J. Biol. Chem. 246:3769, 1971). In 1973, they discovered that the catabolism of Tay-Sachs ganglioside (GM2) requires a protein cofactor in addition to the enzyme (beta-hexosaminidase A) (J. Biol. Chem. 248:7512, 1973). Subsequently, type AB Tay-Sachs disease was established to be the deficiency of this protein cofactor. They have also discovered a new variant of Type AB GM2-gangliosidosis (Biochem. Biophys, Commun. 101:479-485, 1981), which is now called variant B1. They have successfully cloned the gene for GM2 activator protein and overexpressed this gene in E. coli to produce the recombinant activator protein (J. Biol. Chem. 269:16276, 1994). The crystal structure of this activator protein was solved in collaboration with C. S. Wright of the University of Virginia. Their laboratory has also found that the catabolism of GM2 in man is different from that of mouse (J. Biol. Chem. 273:66, 1998). The results provided an explanation on why the Hex A-knock out mouse (the murine model for variant B Tay-Sachs disease) is phenotypically different from human variant B Tay-Sachs disease. They have also deciphered the nucleotide sequence of the activator protein gene that is responsible for expressing the different specificity of the protein cofactors in man and mouse (J. Biol. Chem. 274:28612, 1999). They have recently detected the presence of a taurine-conjugated GM2 in Tay-Sachs brain (J. Biol. Chem. 278:35286, 2003). Since taurine-conjugation is a well-known detoxification mechanism in higher animals to remove xenobiotics by increasing their aqueous solubility, they hypothesized that neural tissues may use taurine-conjugation as a vehicle for removing the excessive accumulation of GM2 in TS brain.
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