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Oxygen reactivity with pyridoxal 5'-phosphate enzymes: biochemical implications and functional relevance

Bisello, G; Longo, C; Rossignoli, G; Phillips, RS; Bertoldi, M; (2020) Oxygen reactivity with pyridoxal 5'-phosphate enzymes: biochemical implications and functional relevance. Amino Acids 10.1007/s00726-020-02885-6. (In press). Green open access

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Abstract

The versatility of reactions catalyzed by pyridoxal 5'-phosphate (PLP) enzymes is largely due to the chemistry of their extraordinary catalyst. PLP is necessary for many reactions involving amino acids. Reaction specificity is controlled by the orientation of the external aldimine intermediate that is formed upon addition of the amino acidic substrate to the coenzyme. The breakage of a specific bond of the external aldimine gives rise to a carbanionic intermediate. From this point, the different reaction pathways diverge leading to multiple activities: transamination, decarboxylation, racemization, elimination, and synthesis. A significant novelty appeared approximately 30 years ago when it was reported that some PLP-dependent decarboxylases are able to consume molecular oxygen transforming an amino acid into a carbonyl compound. These side paracatalytic reactions could be particularly relevant for human health, also considering that some of these enzymes are responsible for the synthesis of important neurotransmitters such as γ-aminobutyric acid, dopamine, and serotonin, whose dysregulation under oxidative conditions could have important implications in neurodegenerative states. However, the reactivity of PLP enzymes with dioxygen is not confined to mammals/animals. In fact, some plant PLP decarboxylases have been reported to catalyze oxidative reactions producing carbonyl compounds. Moreover, other recent reports revealed the existence of new oxidase activities catalyzed by new PLP enzymes, MppP, RohP, Ind4, CcbF, PvdN, Cap15, and CuaB. These PLP enzymes belong to the bacterial and fungal kingdoms and are present in organisms synthesizing bioactive compounds. These new PLP activities are not paracatalytic and could only scratch the surface on a wider and unexpected catalytic capability of PLP enzymes.

Type: Article
Title: Oxygen reactivity with pyridoxal 5'-phosphate enzymes: biochemical implications and functional relevance
Location: Austria
Open access status: An open access version is available from UCL Discovery
DOI: 10.1007/s00726-020-02885-6
Publisher version: https://doi.org/10.1007/s00726-020-02885-6
Language: English
Additional information: © 2020 Springer Nature Switzerland AG. This article is licensed under a Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/).
Keywords: Aromatic aldehyde, Decarboxylase, Oxidase activity, Oxidative stress, Pyridoxal 5′-phosphate-dependent enzymes
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health > Developmental Neurosciences Dept
URI: https://discovery.ucl.ac.uk/id/eprint/10109614
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