Cell wall constituents bacteria

Like all bacteria, actinomycetes are prokaryotic microorganisms. In addition, the adenine-thymine and guanine-cytosine contents of bacteria and actinomycetes are similar, as are the cell wall constituents of both types of microorganisms. Actinomycetes filaments are also about the same size as those of bacteria. 

A recently published book provides an excellent survey of issues that relate to contamination with endotoxins (present in both viable and nonviable bacteria), their released cell wall constituents, and also viable bacteria in the pharmaceutical industry [1]. It is important to know both the content of the work environment (e.g., indoor air) and the pharmaceutical products themselves. The former provides information on possible sources of microbial contamination and the latter the purity of the final commercial product (or precursors in various stages in its preparation). In some cases it is vital to know the actual bacterial species involved in contamination culture-based methods are standard microbiological techniques which were the focus of Jimenez [1] and thus will not be discussed further. Any contamination (e.g., with endotoxins), regardless of the species of origin, is of utmost of importance (e.g., in determining the safety of a batch of antibiotics to be administered intravenously). This is determined optimally by non-culture-based methods. 

A number of D-amino acids have been found to be constituents of peptides in the cell walls of bacteria. 

This particular mycoside Ci preparation contains three different deoxy-hexoses 6-deoxytalose, 6-deoxy-3-0-methyltalose, and 3,4-di-O-methyl-rhamnose. The peptide portion of this mycoside C contains three different amino acids linked in a pentapeptide. One molecular proportion contains one molecule of u-phenylalanine, two molecules of D-o/Io-threonine, atid two molecules of D-alanine the pentapeptide has the structure D-Phc-D-allo-Thr-D-Ala-D-oZZo-Thr-D-Ala. The unnatural configuration of all of the constituent amino acids and the presence of D-oWo-thrconine arc remarkable features. It may be recalled that D-amino acids have also been found in the peptide portion of wax D (see page 220) and arc usually found in the cell walls of bacteria. 

Because of the great importance of glycoconjugates as cell wall constituents of bacteria and as cell membrane constituents of 1 vertebrates (essentially glycosphingolipids and glycoproteins), a few applications to their syntheses will be discussed. 

Lysozyme catalyzes the hydrolysis of a polysaccharide that is the major constituent of the cell wall of certain bacteria. The polymer is formed from /3( 1 —> 4)-linked alternating units of IV-acetylglucosamine (NAG) and N-acetyl-muramic acid (NAM) (Figure 1.25). The solution of the structure of lysozyme... 

The cell walls do not contain muramic acid. Ihe characteristic constituent of the pcplidnglycuns that form lxicten.il cell walls. (2l Their mciaholism differs markedly from bacteria. A number nf coenzymes apparently unique 10 methanogens have been identified. Some of these enzymes are involved in methyl transfer reactions, including the formation of methane. One of the coenzymes is possibly the smallesi coen/yme yet... 

The 3-deoxy-D-ma/ino-2-octulosonic acid 8-phosphate synthase (KDO synthase or KdoS EC 4.1.2.16) is an enzyme involved in the biosynthesis of the eight-carbon sugar KDO [63], a constituent of the capsular polysaccharides (K-antigens) and outer membrane lipopolysaccharides (LPS, endotoxin) of Gram-negative bacteria [156], as well as of the cell wall of algae and a variety of plants [157], In vivo, the enzyme catalyzes the irreversible addition of 26 to D-arabinose 5-phosphate (Ara5P, 32) to form KDO 8-phosphate 33 [158]. The... 

The antimicrobial activity of eugenol may be associated with structural damage and alteration of the permeability mechanism of microsome, lysosome, and cell walls. The substance acts primarily on cytoplasm membranes, causing alteration of its permeability, and thus allowing leakage of essential bacterial cell constituents with subsequent death of the bacteria. 

Some of the less common d enantiomers of amino acids are also found in nature. For example, D-glutamic acid is found in the cell walls of many bacteria, and D-serine is found in earthworms. Some naturally occurring amino acids are not a-amino acids y-Aminobutyric acid (GABA) is one of the neurotransmitters in the brain, and jS-alanine is a constituent of the vitamin pantothenic acid. 

Cell walls are biochemically rather inert with reduced digestibility to many organisms because of their complex cellulose, pectin, and lignin molecules. Callose and lignin are often accumulated at the site of infection or wounding (6,7) and form a penetration barrier. Synthesis of inhibitory proteins (e.g., lectins, protease inhibitors) or enzymes (e.g., chitinase, lysozyme, hydrolases, nucleases) that could degrade microbial cell walls or other microbial constituents would be protective, as well as synthesis of peroxidase and phe-nolase, which could help inactivate phytotoxins produced by many bacteria and fungi. These proteins are either stored in the vacuole... 

Sulfolobus species are archaebacteria, distinct from other leaching bacteria, which are eubacteria. They are usually found in acidic environments with temperatures in the range 50-80°C. Archaebacteria lack muramic acid, a constituent of the eubacterial cell wall. Sulfolobus cells are typically small and spherical (0.7-1.0 pm in diameter). They lack true cell walls, being surrounded by a plasma membrane... 

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