Sialidase bacterial

Compound 34 (BCZ-1812, RWJ-270201, peramivir) showed selective inhibition of influenza virus sialidases over bacterial and mammalian sialidases (Babu et al. 2000 Bantia et al. 2001 Sidwell and Smee 2002). Successful inhibition of influenza virus infectivity in vitro (Smee et al. 2001) and upon oral administration in vivo [mice (Bantia et al. 2001) and ferrets, reviewed in Sidwell and Smee 2002] led to human clinical trials of orally administered peramivir (Barroso et al. 2005). While orally administrated peramivir successfully completed animal studies and Phase I and Phase II clinical trials, in which the compound was showing neither major side effects nor toxicity (Sidwell and Smee 2002), preliminary results of the Phase III trials (June 2002) demonstrated no statistically significant difference in the primary efficacy endpoint, possibly due to low bioavailability (Barroso et al. 2005). 

Hagiwara T, Kijima-Suda I, Ido T, Ohrui H, Tomita K (1994) Inhibition of bacterial and viral sialidases by 3-fluoro-V-acetyIneuraminic acid, Carbohydr Res 263 167-172 Haskell TH, Peterson FE, Watson D, Plessas NR, Culbertson T (1970) Neuraminidase inhibition and viral chemotherapy, J Med Chem 13 697-704 Hatakeyama S, Sugaya N, Ito M, Yamazaki M, Ichikawa M, Kimura K, Kiso M, Shimizu H, Kawakami C, Koike K, Mitamura K, Kawaoka Y (2007) Emergence of influenza B viruses with reduced sensitivity to neuraminidase inhibitors, JAMA 297 1435-1442 Hay AJ (1992) The action of adamantanamines against influenza A viruses inhibition of the M2 ion channel protein, Semin Virol 3 21-30... 

Only a few bacterial and viral sialidases have been purified to high purity or even to protein homogeneity."0 Complete purification of sia-lidase on a preparative scale from the culture filtrate ofC. perfringens was achieved111 by using poly(acrylamide) gel-electrophoresis as the final purification step (see Section VI,1). It is necessary that such purified sialidases be available, as the presence of proteases or other gly-cosidases in the enzyme preparations would lead to severe errors, not only in studies of substrate specificity, but also in cell biological and medical studies (see Sections VI and VII). 

For routine, enzymic hydrolysis of sialic acids on a preparative or an analytical scale in our laboratory, the substrates are incubated with bacterial sialidases in 50 mM acetate buffer at pH 5.5 and 37° for times ranging between a few minutes and several hours, depending on the substrate.107 After incubation, the sialic acids liberated are separated by dialysis, ultrafiltration, or protein precipitation at 0-2°, and purified as will be described in the following Section. 

Apart from the 4-O-acetylated sialic acids, another sialidase-resist-ant sialic acid exists in Nature, namely, the internal, Gal-bound, sialic acid residue of GM,. In contrast to this side-positioned sialic acid, the sialyl residues bound to the peripheral Gal of gangliosides, or to both the peripheral and the internal sialic acid residues forming oligo-sialvl chains in several members of the large ganglioside family,la can be readily removed by sialidases, as was tested with viral, bacterial, and mammalian enzymes.35 -35 1... 

Application of sialidase inhibitors for medical use is still in a premature state. It is imaginable that inhibitors would be useful drugs in infections, caused by micro-organisms, that lead to extensive production of sialidase, for example, in gas edema.371 In the oral cavity, plaque formation and dental caries may be influenced by desialylation of salivary glycoconjugates,399 and bacterial sialidases may play a role therein. This process may be retarded by secretion of the inhibitor Neu2en5Ac in saliva at concentrations which, in some cases, were found to be close to the K value for sialidases.34... 

On the basis of this anti-proteolytic effect of sialic acids, a hypothetical model435 for the role of sialidase in clostridial infections is shown in Scheme 4. It is considered that the bacterial enzyme releases sialic acids from cell-surface glycoproteins of the infected tissue, which thereafter can be readily attacked by proteases. This cooperation between sialidase and protease may support the spreading of the bacteria. Acylneuraminate pyruvate-lyase, also shown in this model, degrades sialic acids for energy supply, and growth, of the bacteria. 

IgG receptors on cultured, human lymphocytes.526 Sialidase treatment of lymphocytes from sensitized subjects increased the responsiveness to viral, bacterial, and fungal antigens.527 The same treatment of human, Herpes simplex virus-infected cells was found to enhance the sensitivity of the cells to lysis mediated by antibody and complement.528... 

Crystals of pronase-released heads of the N2 human strains of A/Tokyo/3/67 [44] and A/RI/5+/57 were used for an x-ray structure determination. The x-ray 3-dimensional molecular structure of neuraminidase heads was determined [45] for these two N2 subtypes by a novel technique of molecular electron density averaging from two different crystal systems, using a combination of multiple isomorphous replacement and noncrystallographic symmetry averaging. The structure of A/Tokyo/3/67 N2 has been refined [46] to 2.2 A as has the structures of two avian N9 subtypes [47-49]. Three influenza type structures [50] have also been determined and found to have an identical fold with 60 residues (including 16 conserved cysteine residues) being invariant. Bacterial sialidases from salmonella [51] and cholera [52] have homologous structures to influenza neuraminidase, but few of the residues are structurally invariant. 

The majority of other modifications examined at the C-4 position of Neu5Ac2en involved A -alkylation or /V-acylation of 4-amino-4-deoxy-Neu5Ac-2en or modification of the guanidino substituent of Zanamivir. IV-Methylamino (22), A -al lyl (23), and Ar,Ar-dimethylamino (24) derivatives of amine 9 were effective inhibitors of NA from influenza A and B viruses (A) = 10 5-10 7M) though they showed diminished activity against a number of bacterial sialidases.57,65... 

T. Hagiwara, I. Kijima-Suda, T. Ido, H. Ohrui, and K. Tomita, Inhibition of bacterial and viral sialidases by 3-fluoro-jV-acetylneuraminic acid, Carbohydr. Res., 263 (1994) 167-172. 

The roles of enteric bacterial sialidase, sialate O-acetyl esterase and glycosulfatase in the degradation of human colonic mucin. Glycoconj J 10, 72-81... 

Another multifunctional bacterial enzyme that has been reported recently is Pasteurella multocida sialyltransferase (PmSTl or tPm0188Ph) (67, 68). It has four different activities, including an a2,3SiaT, a2,6SiaT, a2,3-sialidase, and trans-sialidase activities. PmSTl is a highly active sialyltransferase with broad donor and acceptor substrate specificity therefore it is a powerful tool... 

Deoxy-2,3-didehydro-Neu5Ac (Neu5Ac2en, 148) has long been known to be an inhibitor of sialidases from both bacterial and viral sources [156,157]. Deri-vatisation of the parent compound has been pursued with a view to understanding and improving its inhibitory potency. 

---