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| S. no. | Enzymes | Mechanism | Function | Reference |
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| 1 | Cytochrome P450 | Performs electron transfer reactions and catalysis by reduction or oxidation of heme iron. Utilizes pyridine nucleotides as electron donors producing carbon substrates and oxidized products.
NAD(P)H + O2 + R ⟶ NAD(P)+ + RO + H2O | Synthesis and metabolism of various molecules and chemicals within cells oxidize steroids, fatty acids, and xenobiotics | [37] |
| 2 | Laccase | Reduction of the O2 molecule, including the oxidation of one electron with a wide range of aromatic compounds. | Ring cleavage in aromatic compounds and reduce one molecule of oxygen in the water and produce free radicals | [47] |
| 3 | Dehalogenase | Mainly occurred through three mechanisms:
(1) Hydrolytic mechanism: water molecule serves as a cofactor; halogen substituent is replaced in SN reaction by the hydroxyl group
(2) Oxygenlytic mechanism: catalyzed by mono/dioxygenase incorporating one/two atoms of molecular oxygen into the substrate
(3) Reductive mechanism: it is related to the carbamide family; in this course, halogen is substituted by hydrogen under aerobic conditions, where organohalides are used as the terminal electron acceptors | Cleaves the carbon-halogen bond and eliminates the halogens | [48, 49] |
| 4 | Dehydrogenase | Catalyze the reactions with coenzymes such as NAD+/NADP+ or flavin such as FAD and FMN as an electron acceptor. It transfers two hydrogen atoms from organic compounds to electron acceptors. | Oxidizing organic compounds and generating energy | [5, 50] |
| 5 | Hydrolase | In triglyceride hydrolysis, one-mole triglyceride (T) reacts with three moles of water (W) to produce one-mole glycerol (G), and three-mole fatty acids (P) peptide bond of protein is broken down by hydrolyzing. | Degradation of fats and proteins | [3] |
| 6 | Protease | Catalyze the breakdown of peptide bonds of proteins | Degradation of proteins like keratin, casein, etc., leather dehairing, and wastewater treatment | [51] |
| 7 | Lipase | The transfer of a proton between the aspartate, the histidine, and the serine residues of the lipase followed by hydroxyl residue of the serine attacks the carbonyl group of the substrate. In the deacylation step, nucleophile attacks the enzyme regenerating the enzyme and releasing the product. | Catalyzes the hydrolysis of mono-, di-, and triglycerides into fatty acids and glycerol.
Also, catalyze the esterification and transesterification reactions. | [52] |
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