Introduction Lina
Function
The thiol deoxygenation is the initial oxidation step which allow a thiol to catabolic and biosynthetic pathway. A family of specific non-heme mononuclear iron proteins catalyses the reaction. Each enzyme reacts efficiently with just one substrate. This family includes : cysteine dioxygenase, cysteamine dioxygenase, mercaptosuccinate dioxygenase and 3-mercaptopropionate dioxygenase. (article)
The thiol dioxygenase of P. aeruginose (p3MDO) is a 3-mercaptopropionate (3-MPA) dioxygenase with a secondary cysteine dioxygenase activity. Therefore it can also be named 3-mercaptopropionate dioxygenase or cysteine dioxygenase. This is the first exemple of cysteine dioxigenase (CDO) homologue which utilizes a second substrate with near stochiometric coupling to dioxigen consumption. (article)
The cysteine dioxygenase (p3MDO?) homologue from Pseudomonas aeruginosa is expressed in low levels so this metabolic pathway is present in this organism.
The physiological role is unclear.
Cysteine and 3-mercaptopropionic acid contain two thiol.
Catalytic activity:
It catalyses the dioxygenation of 3-mercaptopropionate (3-MPA) to 3-sulfinopropionate.
3-mercaptopropionate + O2 = 3-sulfinopropionate
(uniProt)
It also oxidizes cysteine to cysteine sulfinate.
This enzyme has a marked preference for 3-mercaptopronionate, that’s why this enzyme is describe as a 3-mercaptopropionate dioxygenase. (article)
Disease
Relevance
Structural highlights
Thiol dioxygenase from Pseudomonas aeruginosa is made of 4 chains (named A, B, C, D). Each chain is made of 211 amino acids. For its secondary structures, it has and . The different binding sites with an atom of iron are three different Histidines : , Histidine 91 and Histidine 142.
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