Asymmetry of the Active Site Loop Conformation between Subunits of Glutamate-1-semialdehyde Aminomutase in Solution.
Glutamate-1-semialdehyde aminomutase (GSAM) is a dimeric, pyridoxal 5'-phosphate (PLP)-dependent enzyme catalysing in plants and some bacteria the isomerization of L-glutamate-1-semialdehyde to 5-aminolevulinate, a common precursor of chlorophyll, haem, coenzyme B12, and other tetrapyrrolic compound...
| Publicado en: | BioMed Research International Vol. 2013; pp. 353270 - 353271 |
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| Autores principales: | , , , , |
| Formato: | Journal Article |
| Publicado: |
Wiley-Blackwell
2013
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=104090753&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 104090753 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 23146133 FT2T jtl: BioMed Research International issn: 23146133 maglogo: N pubinfo: dt: 2013 vid: 2013 pid: 480 pub: Wiley-Blackwell place: Malden, Massachusetts artinfo: ui: 104090753 2012240530 NLM23984351 PMC3747428 104090753 ppf: 353270 ppct: 1 formats: fmt: @attributes: type: P tig: atl: Asymmetry of the Active Site Loop Conformation between Subunits of Glutamate-1-semialdehyde Aminomutase in Solution. aug: au: Campanini, Barbara Bettati, Stefano di Salvo, Martino Luigi Mozzarelli, Andrea Contestabile, Roberto affil: Dipartimento di Farmacia, Università di Parma, Parco Area delle Scienze 23/A, 43124 Parma, Italy. sug: subj: Amino Acids Enzymes Enzymes Metabolism Proteins Proteins Metabolism Gram-Negative Bacteria Absorption Biochemical Phenomena Drug Effects Coenzymes Metabolism Chemistry Potassium Iodide Pharmacodynamics Vitamin B Complex Metabolism Pyridoxine Metabolism Solutions Spectrometry, Fluorescence ab: Glutamate-1-semialdehyde aminomutase (GSAM) is a dimeric, pyridoxal 5'-phosphate (PLP)-dependent enzyme catalysing in plants and some bacteria the isomerization of L-glutamate-1-semialdehyde to 5-aminolevulinate, a common precursor of chlorophyll, haem, coenzyme B12, and other tetrapyrrolic compounds. During the catalytic cycle, the coenzyme undergoes conversion from pyridoxamine 5'-phosphate (PMP) to PLP. The entrance of the catalytic site is protected by a loop that is believed to switch from an open to a closed conformation during catalysis. Crystallographic studies indicated that the structure of the mobile loop is related to the form of the cofactor bound to the active site, allowing for asymmetry within the dimer. Since no information on structural and functional asymmetry of the enzyme in solution is available in the literature, we investigated the active site accessibility by determining the cofactor fluorescence quenching of PMP- and PLP-GSAM forms. PLP-GSAM is partially quenched by potassium iodide, suggesting that at least one catalytic site is accessible to the anionic quencher and therefore confirming the asymmetry observed in the crystal structure. Iodide induces release of the cofactor from PMP-GSAM, apparently from only one catalytic site, therefore suggesting an asymmetry also in this form of the enzyme in solution, in contrast with the crystallographic data. pubtype: Academic Journal doctype: Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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