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Phase I - Functionalization of compounds

Summary

Organism

Homo sapiens (human)

Reactome

R-HSA-211945

PubChem

R-HSA-211945

Description

Phase 1 of metabolism is concerned with functionalization, that is the introduction or exposure of functional groups on the chemical structure of a compound. This provides a 'handle' for phase 2 conjugating species with which to react with. Many xenobiotics are lipophilic and almost chemically inert (e.g. PAHs) so would not necessarily undergo a phase 2 reaction. Making them more chemically reactive would facilitate their excretion but also increases their chance of reacting with cellular macromolecules (e.g. proteins, DNA). There is a fine balance between producing a more reactive metabolite and conjugation reactions.
There are two groups of enzymes in phase 1 - oxidoreductases and hydrolases. Oxidoreductases introduce an oxygen atom into or remove electrons from their substrates. The major oxidoreductase enzyme system is called the P450 monooxygenases. Other systems include flavin-containing monooxygenases (FMO), cyclooxygenases (COX) and monoamine oxidases (MAO). Hydrolases hydrolyse esters, amides, epoxides and glucuronides.

Click on a node on the pathway to see its details. Glycoproteins are marked with a glycoprotein icon in their name.

SPV: a JavaScript Signaling Pathway Visualizer, Bioinformatics, 2018

Displaying entries **1 - 10** of 11 in total

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UniProt ID	Protein Name	Gene Symbol	Pathway Viewer
O00748	Cocaine esterase	CES2 ICE	view
O75106	Amine oxidase [copper-containing] 2	AOC2	view
O75828	Carbonyl reductase [NADPH] 3	CBR3 SDR21C2	view
P00387	NADH-cytochrome b5 reductase 3	CYB5R3 DIA1	view
P19801	Diamine oxidase [copper-containing]	ABP ABP1 AOC1 DAO	view
P22760	Arylacetamide deacetylase	AADAC DAC	view
P23141	Liver carboxylesterase 1	CES1 CES2 SES1	view
P27540	Aryl hydrocarbon receptor nuclear translocator	ARNT BHLHE2	view
P35869	Aryl hydrocarbon receptor	AHR BHLHE76	view
Q16853	Amine oxidase [copper-containing] 3	AOC3 VAP1	view

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