Sialidases functions

Rye CS, Withers SG (2000) Glycosidase mechanisms, CurrOpin Chem Biol 4 573-580 Saito M, Yu RK (1995) Biochemistry and function of sialidases. In Rosenberg A (ed) Biology of the sialic acids. Plenum, NY, pp 261-313... 

Because sialoglycoconjugates are essential components of cells and body fluids, and are frequently involved in specific, biological functions, sialidases may become toxic enzymes when present in non-physiological amounts. On the other hand, absence or lessening of the normal amount of this enzyme may lead to diseases, as became evident in studies of some fonns of mucolipidoses and sialidoses, respectively. 

The first method has been widely applied. In some instances, removal of terminal sialic acid by using sialidases modified the function of the glycoprotein, but, in others, the function was not changed. The results of such investigations are listed in a review by L. Warren and coworkers.416... 

A. C. C. Frash, Functional diversity in the trans-sialidase and mucin families in Trypanosoma cruzi, Parasitol. Today, 16 (2000) 282-286. 

Sialidase or NA is the second glycoprotein on the virion surface. One of the most important functions of sialidase is associated with the release of virus progeny from infected host cells to repeat the cycle of infection [6, 50], The enzyme catalyzes the hydrolysis of sialic acid residues from glycoconjugates on the cell surface with either Neu5Ac(a2 3)Gal or Neu5Ac(a2 6)Gal linkages (Gal=galactose) [60, 61]. 

Functionalization of the C7 Position of Zanamivir X-ray studies of influenza virus sialidase in complex with a-Neu5Ac [66] and zanamivir [91] showed that the C7-OH is not involved in any direct interaction in the active site of influenza virus NA, and only the C8- and C9-hydroxy groups are involved in the binding interactions. Based on this knowledge, different manipulations have been attempted at Cl, for example, by a simple substitution of the C7-hydroxy group or alkylation... 

Monitoring of the levels of total sialic acid and lipid-associated sialic acid in serum is an important diagnostic tool for the detection of precancerous lesions [224], Transition-state analogues derived from sialic acid are potent inhibitors of sialidases from various influenza virus strains, and these have been evaluated clinically as influenza remedies [225], A detailed review of our current knowledge regarding the occurrence, specificity and function of sialic acid-specific lectins, particularly those that occur in viruses, bacteria and non-vertebrate eukaryotes has been recently published [226],... 

C. A. Buscaglia, V. A. Campo, A. C. C. Frasch, and J. M. Di Noia, Trypanosoma cruzi surface mucins host-dependent coat diversity, Nat. Rev. Microbiol, 4 (2006) 229-236 A. C. C. Frasch, Functional diversity in the trans-sialidase and mucin families in Trypanosoma cruzi, Parasitol. Today, 16 (2000) 282-286. 

S. Schenkman, D. Eichinger, M. E. S. Pereira, and V. Nussenzweig, Structural and functional properties of Trypanosoma trans-sialidase, Annu. Rev. Microbiol., 48 (1994) 499-523. 

K. B. Lee and Y. C. Lee, Transfer of modified sialic acids by Trypanosoma cruzi trans-sialidase for attachment of functional groups to oligosaccharide, Anal. Biochem., 216 (1994) 358—364. 

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