Biomaterial Database

Chemical structure of the peptidoglycan, its modifiability and relation to the biological activity. 1975

K H Schleifer

The peptidoglycan is a heteropolymer composed of polysaccharide chains which are cross-linked through short peptides. The polysaccharide moiety (glycan) is made up of beta-1,4 glycosidically linked N-acetylglucosamine and N-acylmuramic acid residues. The carboxyl group of muramic acid is usually substituted by a peptide which consists of alternating L- and D-amino acids. These peptide subunits are cross-linked between the diamino acid in position 3 and the C-terminal D-alanine in position 4 of an adjacent peptide subunit either in a direct way or via an interpeptide bridge (Group A). In some coryneform bacteria the cross-linkage extends from the alpha-carboxyl group of D-glutamic acid in position 2 to D-alanine of a neighbouring peptide subunit (Group B). In the latter case a diamino acid is always found in the interpeptide bridge. A chemical modification of the peptidoglycan may occur in some bacteria due to growth in a quite unbalanced medium. The influence of glycine-rich and glycine-deficient growth medium on the chemical structure of the peptidoglycan of S. aureus will be discussed. Inhibiting concentrations of penicillin, glycine or D-amino acids can also modify the peptidoglycan. Further modification can occur through different extraction procedures which are used to obtain a clean peptidoglycan free of non-peptidoglycan cell wall material. Little is known about the molecular basis of the biological activity. The chemical composition is at least important for the antigenic determinants. The lysozyme susceptibility and the size of the preparation may be other crucial points for the biological activity of the peptidoglycan.

UI	MeSH Term	Description	Entries
D009112	Muramic Acids	Compounds consisting of glucosamine and lactate joined by an ether linkage. They occur naturally as N-acetyl derivatives in peptidoglycan, the characteristic polysaccharide composing bacterial cell walls. (From Dorland, 28th ed)	Muramic Acid,Acid, Muramic,Acids, Muramic
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
D010457	Peptidoglycan	A structural polymer of the bacterial cell envelope consisting of sugars and amino acids which is responsible for both shape determination and cellular integrity under osmotic stress in virtually all bacteria.	Murein,Pseudomurein
D011134	Polysaccharides	Long chain polymeric CARBOHYDRATES composed of MONOSACCHARIDES linked by glycosidic bonds.	Glycan,Glycans,Polysaccharide
D002473	Cell Wall	The outermost layer of a cell in most PLANTS; BACTERIA; FUNGI; and ALGAE. The cell wall is usually a rigid structure that lies external to the CELL MEMBRANE, and provides a protective barrier against physical or chemical agents.	Cell Walls,Wall, Cell,Walls, Cell
D003352	Corynebacterium	A genus of asporogenous bacteria that is widely distributed in nature. Its organisms appear as straight to slightly curved rods and are known to be human and animal parasites and pathogens.
D000117	Acetylglucosamine	The N-acetyl derivative of glucosamine.	Acetyl Glucosamine,N-Acetyl Glucosamine,N-Acetyl-beta-D-Glucosamine,N-Acetylglucosamine,beta-N-Acetylglucosamine,2-Acetamido-2-Deoxy-D-Glucose,2-Acetamido-2-Deoxyglucose,N-Acetyl-D-Glucosamine,2 Acetamido 2 Deoxy D Glucose,2 Acetamido 2 Deoxyglucose,Glucosamine, Acetyl,Glucosamine, N-Acetyl,N Acetyl D Glucosamine,N Acetyl Glucosamine,N Acetyl beta D Glucosamine,N Acetylglucosamine,beta N Acetylglucosamine
D013210	Staphylococcus	A genus of gram-positive, facultatively anaerobic, coccoid bacteria. Its organisms occur singly, in pairs, and in tetrads and characteristically divide in more than one plane to form irregular clusters. Natural populations of Staphylococcus are found on the skin and mucous membranes of warm-blooded animals. Some species are opportunistic pathogens of humans and animals.
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships