1 Classification reactions Carbohydrates

In this section, enzymes in the EC 2.4. class are presented that catalyze valuable and interesting reactions in the field of polymer chemistry. The Enzyme Commission (EC) classification scheme organizes enzymes according to their biochemical function in living systems. Enzymes can, however, also catalyze the reverse reaction, which is very often used in biocatalytic synthesis. Therefore, newer classification systems were developed based on the three-dimensional structure and function of the enzyme, the property of the enzyme, the biotransformation the enzyme catalyzes etc. [88-93]. The Carbohydrate-Active enZYmes Database (CAZy), which is currently the best database/classification system for carbohydrate-active enzymes uses an amino-acid-sequence-based classification and would classify some of the enzymes presented in the following as hydrolases rather than transferases (e.g. branching enzyme, sucrases, and amylomaltase) [91]. Nevertheless, we present these enzymes here because they are transferases according to the EC classification. 

DOT CLASSIFICATION 8 Label Corrosive DOT Class 8 Label Corrosive, Poison SAFETY PROFILE Confirmed human carcinogen. A poison. Moderately toxic by inhalation. A corrosive irritant to skin, eyes, and mucous membranes. A very dangerous fire hazard by chemical reaction with reducing agents and carbohydrates. A severe explosion hazard by chemical reaction with acetic acid, acetic anhydride, acetonitrile, acrolein, acrylic acid, acrylonitrile, aUyl... 

Most important in the classification of sulfur bacteria is the distinction between phototrophic and chemotrophic sulfur bacteria. Phototrophic (purple or green) bacteria use light as energy source to reduce CO2 to carbohydrates. Reduced sulfur compounds are used as an electron donor for this reduction, which takes place under anaerobic conditions. The oxidation reactions of sulfide to sulfur and sulfate by phototrophic bacteria are called the Van Niel reactions ... 

The pr e-Woodwardhn era largely concerned itself with the collection and classification of synthetic tools chemical reactions suited to broad application to the constitutional construction of molecular skeletons (including Kiliani s chain-extension of aldoses, reactions of the aldol type, and cycloadditions of the Diels-Alder type). The pre- Woodwardian era is dominated by two synthetic chemists Emil Fischer and Robert Robinson. Emil Fischer was emphasizing the importance of synthetic chemistry in biology as early as 1907 [30]. He was probably the first to make productive use of the three-dimensional structures of organic molecules, in the interpretation of isomerism phenomena in carbohydrates with the aid of the Van t Hoff and Le Bel tetrahedron model (cf. family tree of aldoses in Scheme 1-6), and in the explanation of the action of an enzyme on a substrate, which assumes that the complementarily fitting surfaces of the mutually dependent partners are noncovalently bound for a little while to one another (shape complementarity) [31],... 

Natural polymers are broadly classified as polysaccharides, proteins, polynucleotide, and natural rubber. This classification is based on the type of monomer building blocks for the polymer and type of covalent bonds for formation of the polymer. Polysaccharides that are carbohydrate polymers are formed by condensation of monomeric units called monosaccharides, proteins or peptide polymers are formed from amino acids and polynucleotide are synthesized from nucleotide condensation reaction forming glycosidic, peptide, and phosphodiester bonds, respectively. All natural polymers are condensation polymers. 

Small doses of adrenaline, inactive in control animals, have also been reported to protect adrenalectomized rats from the severe shock produced by egg-white [120, 244]. In fact, it has been suggested that the adrenal medulla, and not the adrenal cortex, protects rats from a fatal anaphylactoid response [392, 606]. Moreover, both adrenaline and noradrenaline inhibit the anaphylactoid reaction produced by egg-white [94, 119, 231, 248, 489] or dextran [125, 250] in the intact animal. Noradrenaline (a more potent vasoconstrictor than adrenaline) was always less active in these studies so that inhibition is probably not related to vasoconstriction (a classical alpha adrenergic action on the Ahlquist classification of adrenergic receptors [19]). Protection may involve an effect on carbohydrate metabolism as adrenaline is more potent than noradrenaline in producing hyperglycaemia [75, 356]. Moreover, the inhibitory effect of adrenaline on the anaphylactoid reaction [445] and its hyperglycaemic activity [116, 604] are inhibited by beta, but not by alpha, adrenergic blockade. 

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