Publisher Summary Lipopolysaccharides (LPS) form a large, unique class of macromolecules representing a characteristic attribute of gram-negative bacteria. Associated with proteins, they are located in the outer leaflet of the outer membrane of the bacterial cell. In this exposed position on the cell surface, lipopolysaccharides are involved in the interaction of the cell with the environment. Thus, contact of the bacterium with the immune system leads to the stimulation of specific antibodies directed predominantly against determinant structures of the lipopolysaccharide. Hence, lipopolysaccharides represent the main surface antigens of gram-negative bacteria. The chapter describes general aspects of the O-specific chains and the core, and principles of their biosynthesis. The O-specific chains of lipopolysaccharides are made up of repeating units of identical oligosaccharides. These units usually contain different constituents, thus the O chain represents a heteropolysaccharide. The chapter discusses the structure of Salmonella lipopolysaccharides (lipid A), and its biosynthesis. Lipid A's of other gram-negative bacteria, recently investigated is also described. The smallest lipid A substructure exhibits antigenicity, mitogenicity, lethal toxicity, (weak) pyrogenicity, and (weak) complement reactivity, but strong Limulus lysate activity. Some aspects of the biological properties of lipopolysaccharides are also discussed. In Gram-positive and Gram-negative bacteria, cell wall components other than lipopolysaccharide may also be endowed with endotoxin-like activities. Like lipopolysaccharide, these constituents are amphipathic in nature (probably with the exception of murein, though it may contain lipoprotein). Thus, the studies indicate that at least some lipid A activities are not restricted to one specific structure, but are rather connected with general physicochemical properties.

Lipopolysaccharides of Gram-Negative Bacteria

Publisher Summary This chapter discusses the preparation of pharmaceutical compounds by immobilized enzymes and cells Immobilized enzymes and cells can be used to prepare many pharmaceutical compounds Industrial exploitation of enzymes and microorganisms traditionally has been accomplished by using intact microorganisms or soluble cell free enzyme preparations These processes are not very efficient because the catalysts (enzymes or microorganisms) are used for just one batch reaction or fermentation Additional uses are not feasible because: enzymes and cells are relatively unstable and may lose activity during a fermentation or reaction; and conventional recovery methods are either expensive or cause denaturation and loss of catalytic activity If enzymes and microorganisms are to be reused effectively, their stability must be improved, and inexpensive non-destructive recovery methods must be developed Immobilization offers a means of achieving both objectives

Preparation of pharmaceutical compounds by immobilized enzymes and cells.

Penicillin V acylase : its potential in the production of 6-aminopenicillanic acid

Molecular aspects of penicillin and cephalosporin acylases

Etude portant sur la purification, les methodes de dosage, les proprietes physicochimiques et cinetiques de l'enzyme. On decrit aussi brievement sa biosynthese

Penicillin acylases. An update

Une penicilline V-acylase intracellulaire, produite par une soucheErwinia aroideae a ete purifiee et caracterisee. Cette enzyme presente des proprietes differentes des penicilline-acylases classiques.

Properties of the purified penicillin V-acylase of Erwinia aroideae.

La biodegradation parBacillus macerans des lipopolysaccharides (LPS), extraites deSalmonella typhimurium, Salmonella minnesota et Escherichia coli fut etudiee dans un milieu liquide mineral, contenant uniquement ces LPS comme sources de carbone. II fut observe qu'apres avoir effectue une hydrolyse des LPS le microorganisme se developpe sur les acides gras, liberes de la fraction lipidique. Apres 17 jours de croissance la fraction polysaccharide etait encore intact. Le meme phenomene de biodegradation fut observe avec une souche typiquement lipolytique (Micrococcus sp.).

E. J. Vandamme

Papers

Properties of the purified penicillin V-acylase of Erwinia aroideae.

Biodegradation of microbial lipopolysaccharides.