Sensitized Photooxygenation And Peroxidase-catalyzed Inactivation Of Xanthine Oxidase--evidence Of Cysteine Damage By Singlet Oxygen.

dc.creatorJusto, G Z
dc.creatorCamargo, F A
dc.creatorHaun, M
dc.creatorFaljoni-Alário, A
dc.creatorDurán, N
dc.date2000
dc.date2015-11-27T12:22:52Z
dc.date2015-11-27T12:22:52Z
dc.date.accessioned2018-03-29T00:54:44Z
dc.date.available2018-03-29T00:54:44Z
dc.identifierPhysiological Chemistry And Physics And Medical Nmr. v. 32, n. 2, p. 145-54, 2000.
dc.identifier0748-6642
dc.identifier
dc.identifierhttp://www.ncbi.nlm.nih.gov/pubmed/11383136
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/194681
dc.identifier11383136
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1294914
dc.descriptionXanthine oxidase (XO) has been investigated for its decreased activity in several cancerous tissues and constitutive generation of reactive oxygen species (ROS) in vivo seems to contribute significantly to its inactivation. Singlet oxygen (1O2) production has been suggested to be relevant when considering folic acid metabolism by cancer cells. Thus, the susceptibility of XO to inactivation by 1O2 generated either by the bioenergized systems folic acid/peroxidase/GSH/Mn2+/O2 and malonaldehyde/peroxidase/Mn2+/O2 or by methylene blue (MB) or eosin-sensitized photooxygenation was studied. Our results showed that other ROS were also responsible for XO inactivation when MB was used. In contrast, eosin produced almost exclusively 1O2. Kinetic studies of XO oxidation in the malonaldehyde/peroxidase system showed that histidine (His) is a competitive inhibitor with respect to XO. A similar result was observed in the eosin-photosensitized process, suggesting the involvement of 1O2 in both processes. In addition, an efficient quenching of XO oxidation by guanosine in the folic acid/peroxidase system was observed. Amino acid analysis revealed that cysteine (Cys) is more affected than other XO amino acids also prone to oxidation such as tyrosine (Tyr), methionine (Met) and His. These results indicate that 1O2 may cause oxidative damage to the Cys residues of XO, with loss of enzyme activity. Alteration of the flavin prosthetic site is hypothesized.
dc.description32
dc.description145-54
dc.languageeng
dc.relationPhysiological Chemistry And Physics And Medical Nmr
dc.relationPhysiol Chem Phys Med NMR
dc.rightsfechado
dc.rights
dc.sourcePubMed
dc.subjectAmino Acids
dc.subjectCatalysis
dc.subjectCysteine
dc.subjectFolic Acid
dc.subjectGlutathione
dc.subjectHorseradish Peroxidase
dc.subjectIndicators And Reagents
dc.subjectMalondialdehyde
dc.subjectOxidation-reduction
dc.subjectPeroxidase
dc.subjectPhotochemistry
dc.subjectReactive Oxygen Species
dc.subjectSpectrometry, Fluorescence
dc.subjectXanthine Oxidase
dc.titleSensitized Photooxygenation And Peroxidase-catalyzed Inactivation Of Xanthine Oxidase--evidence Of Cysteine Damage By Singlet Oxygen.
dc.typeArtículos de revistas


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