Walls of Gram-positive Bacteria

Teichoic acid chains normally bear a number of substituents which have an important influence upon their molecular properties. For example, D-alanyl groups may be present, attached by an ester linkage between the carboxyl group of D-alanine and a fi-ee hydroxyl group on either glycerol 

The simplest cases are organisms such as Micrococcus luteus and Bacillus megaterium M46 walls of these organisms contain teichuronic acids regardless of the growth conditions. The organisms seem to be unable to produce teichoic acid. By contrast walls of Staphylococcus aureus nearly 

Repeating unit of teichoic acid ribitol phosphate 

AAacetylglucosamine phosphate ribitol phosphate glycerol phosphate 

Linkage of Teichoic and Teichuronic Adds to the Peptidoglycan Layer 

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In the walls of Gram-positive bacteria, molecules of a polyribitol or polyglyeerol-phosphate are attached by covalent links to the ohgosaccharide backbone these entities... 

In addition, all organisms studied contained an amino sugar or hexosamine. Generally, the walls of Gram-positive bacteria are richer in hexosamine than the Gram-negative forms. 

Teichoic and teichuronic acids. The cell walls of gram-positive bacteria are composed of a thick peptidoglycan layer which also contains proteins and additional polymers known as teichoic acids and teichuronic acids. In some species these account for 50% of the dry weight of the cells.598 599 Teichoic acids are high polymers of the following general types ... 

The walls of Gram-positive bacteria, unlike the membranes, sometimes do not contain teichoic acids. However, there are numerous examples of walls which do contain these compounds in substantial proportions, although in relatively few cases has detailed structural work been carried out. The purification of wall teichoic acids is often much more readily achieved than for the membrane polymers. Addition of ethanol to trichloroacetic acid extracts of walls gives a precipitate which is usually pure teichoic acid. Extraction is effected at low temperatures, and for a reasonably short time, in order to avoid extensive degradation of the polymers under the acidic conditions. Consequently, although walls may contain 20-50% by weight of teichoic acid, practiced yields are generally rather low. 

Lysozyme is an enzyme that can cause lysis of the cell walls of Gram-positive bacteria, including lactic acid bacteria in wine (Delfini 2004). Lysozyme maintains its activity in wines with high pH values so it can be used successfully to delay or inhibit the growth of lactic acid bacteria, especially when used together with SO2,... 

Feptidoglycan. The main component of the bacterial cell wall, consisting of a two-dimensional network of heteropolysaccharides running in one direction, cross-linked with pol) eptides running in the perpendicular direction, or Carbohydrate polymer cross-linked by proteins. It is found in the cell wall of gram positive bacteria, where it stains with the dye crystal-violet. 

The cell walls of Gram-positive bacteria, including the pathogens S. aureus. Bacillus anthracis. Streptococcus pneumoniae, and Enterococcus faecalis contain thick layers of peptidoglycan. The peptidoglycan layers serve as both a protective barrier and as a scaffold for the attachment of secondary cell wall polymers and surface proteins. Surface proteins include hydrolytic enzymes involved in peptidoglycan turnover, as well as structures such as pili... 

The cell walls of Gram-positive bacteria are quite thick (20-80 nm) and consist of between 60% and 80% peptidoglycan, which is extensively cross-linked in three dimensions to form a thick polymeric mesh (Fig. 3.3). Gram-positive walls frequently contain acidic polysaccharides called teichoic acids these are either ribitol phosphate or glycerol phosphate molecules that are connected by phos-... 

GH 22 - Lysozyme. The natural substrate of lysozyme is the murein of the cell walls of Gram-positive bacteria (see Figures 5.43 and 4.95(a)). Hen egg-white lysozyme was the first enzyme for which an X-ray structure was available,... 

TddMronicaclds. Poly saccharides, which may contain uronic acids (e.g., D- glucuronic acid or N-ace-tyl-D-mannosaminuronic acid), isolated from the cell walls (hence the name, from Greek teichos=wall) of Gram-positive bacteria. T. a. are either linked directly or via oligosaccharides to the peptidoglycan (murein) of the cell wall. 

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