The structure and catalytic role of decarboxylases of amino acids

Decarboxylases of amino acids consist of apoenzyme and coenzyme as phosphopyridoxal (vitamin B6 + H3PO4). Decarboxylases of amino acids catalyze the decarboxylation of amino acids that results in formation of biogenic, or proteinogenic amines:

5-hydroxytryptophanàserotonin+CO2

Hystidineàhystamine+CO2

Glutamic acidàgamma-aminobutyric acid

Aspartic acidàbeta-alanine+CO2

Phenylalanineàphenylethylamine+CO2

Tyrosineàtyramine+CO2

The structure and catalytic role of carbonic anhydrase

Carbonic anhydrase consists of apoenzyme and coenzyme as zinc. This enzyme catalyzes the reaction of cleavage of H2CO3 to CO2 and H2O: H2CO3↔H2O + CO2. The direction of this reaction depends on CO2 concentration, therefore this enzyme regulates the function of respiratory center

The general characteristic and classification of oxireductases

Oxireductases catalyze oxidative-reductive reactions. They’re two-component enzymes. Oxireductases may divide into 4 groups:

1) dehydrogenases

2) cytochromes

3) catalase and peroxidases

4) oxygenases

Dehydrogenasesoxidize substrates by dint of their dehydrogenation (removal of hydrogen). They participate in biologic oxidation and reduction. There are pyridine and flavin (FP) dehydrogenases and ubiquinone. They may be primary and secondary. Primary DH-ases oxidize substrates. Secondary DH-ases oxidize reduced forms of other DH-ases. Cytochromes are heme-containing enzymes. They take part in transport of electrons. Catalase and peroxidase are heme-containing enzymes. They don’t participate in oxidative-reductive reations, but they cleave H2O2 which is formed in oxidative-reductive processes. Oxygenases may be monooxygenases (hydroxylases) and dioxygenases. They oxidize substrates by dint of inclusion of oxygen.

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The structure, role and representatives of phosphotransferases	\|	The structure and catalytic role of Pyridine enzymes

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