Glycosphingolipid biosynthesis - globoseries
Glycosphingolipid biosynthesis - ganglioseries
Biochemical and molecular aspects of late-onset GM2-gangliosidosis: B1 variant as a prototype.
Crystallization of recombinant chitobiase from Serratia marcescens.
Structure-function studies on the chitinolytic enzymes of Serratia marcescens chitinase and chitobiase.
N-Acetylglucosaminidase (chitobiase) from Serratia marcescens: gene sequence, and protein production and purification in Escherichia coli.
Characterization of glycoproteins and their associated oligosaccharides through the use of endoglycosidases.
Bacterial chitobiase structure provides insight into catalytic mechanism and the basis of Tay-Sachs disease.
Serratia marcescens chitobiase is a retaining glycosidase utilizing substrate acetamido group participation.
Isoenzymes of N-acetyl-beta-hexosaminidase.
The structural basis for the susceptibility of gangliosides to enzymatic degradation.
Structures of chitobiase mutants complexed with the substrate Di-N-acetyl-d-glucosamine: the catalytic role of the conserved acidic pair, aspartate 539 and glutamate 540.
New structural insights into lectin-type proteins of the immune system.
This enzyme belongs to the glycosidase family-20. This enzyme has a retaining mechanism. According to the literature [6], [7] and [10], the reaction of this enzyme proceeds as follows: (0) Asp539 might modulate the general acid, Glu540, by restraining the positioning of Glu540. (1) Glu540 acts as a general acid, to protonate the glycosidic oxygen atom, the O1 atom, leading to the transition state with oxocarbenium ion character. (2) Asp 539 modulate the N-acetyl group of the substrate, by forming a hydrogen bond with the N2 atom of the N-acetyl group. The O7 oxygen atom of the N-acetyl group makes a nucleophilic attack on the C1 atom of the transition state. This nucleophilic substitution seems to be S1-like reaction. (3) A covalent cyclic oxazolinium ion intermediate is formed and stabilized by Asp539, which forms a hydrogen bond with the N2 atom. (4) A water, which is activated by a general base, Glu540, makes a nucleophilic attack on the C1 atom of the intermediate, leading again to the transition state with oxocarbenium ion character. (5) The covalent bond between the C1 atom and the O7 oxygen atom is broken, and finally the product is formed. Thus, Asp539 play multiple roles, a stabilizer for the oxazolinium ion intermediate, and modulators for the N-acetamido group and Glu540 (see [10]).