SCWPs

SCHEME 14.13 Synthesis of the SCWP fragment from Bacillus anthracis by Boons and coworkers. Fmoc, 9-fluorenylmethoxycarbonyl TDS, dimethylthexylsilyl. 

One of the common surface structures of archea and bacteria are monomolecular crystalline arrays of protein subunits, called S-layers [106-109]. They constitute the outermost component of tlie cell envelope of these procaryotic organisms. S-layer subunits can be aligned in lattices with oblique, square, or hexagonal symmetry. Since S-layers are monomolecular assemblies of identical protein subunits, they exhibit pores of identical size and morphology. A group of nonclassical cell wall polymers, called secondary cell wall polymers (SCWPs), are attached noncova-lently, presumably by a lectin-type interaction, to the S-layer proteins. 

Figure 4.11 Schematic of S-layer stabilized solid supported lipid membranes, (a) S-layer directly recrystallized on gold, with a lipid bilayer on top. (b) Same as (a), with an additional S-layer recrystallized on top of the lipid bilayer, (c) Thiolated SCWPs directly bound to gold and interacting with an S-layer, with a lipid bilayer on top. (d) Same as (c).

Gram-positive bacteria also have additional anionic polymers (secondary cell-wall polymers, SCWPs), which are covalently attached to the muramic acid residues of the peptidoglyean and attach cell-surface proteins. They can be of the teichoic acid type, linear copolymers of a sugar alcohol and phosphoric acid, or the teichuronic acid type, in which the anionic component is uronic acids.The commonest teichoic acids are based on 1,3-linked glycerol or 1,5-linked ribitol. 

Millipore filters, type SCWP 02500, of 8 pm pore size... 

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