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Drug
Enzyme
Compound
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Query: UNIPROT:P47989 (
xanthine oxidase
)
8,633
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The degradation of peroxisomal and nonperoxisomal proteins by endoproteases of purified peroxisomes from senescent pea (Pisum sativum L.) leaves has been investigated. In our experimental conditions, most peroxisomal proteins were endoproteolytically degraded. This cleavage was prevented, to some extent, by incubation with 2 mM phenylmethylsulfonylfluoride, an inhibitor of serine proteinases. The peroxisomal enzymes glycolate oxidase (EC 1.1.3.1), catalase (EC 1.11.1.6) and glucose-6-phosphate dehydrogenase (EC 1.1. 1.49) were susceptible to proteolytic degradation by peroxisomal endoproteases, whereas peroxisomal manganese superoxide dismutase (EC 1.15.1.1) was not.
Ribulose
-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) from spinach and urease (EC 3.5. 1.5) from jack bean were strongly degraded in the presence of peroxisomal matrices. These results indicate that proteases from plant peroxisomes might play an important role in the turnover of peroxisomal proteins during senescence, as well as in the turnover of proteins located in other cell compartments during advanced stages of senescence. On the other hand, our data show that peroxisomal endoproteases could potentially carry out the partial proteolysis which results in the irreversible conversion of xanthine dehydrogenase into the superoxide-generating
xanthine oxidase
(EC 1. 1.3.22). This suggests a possible involvement of the peroxisomal endoproteases in a regulated modification of proteins.
...
PMID:Proteolytic cleavage of plant proteins by peroxisomal endoproteases from senescent pea leaves 1050 97
Oryza meyeriana is a wild species of rice with high resistance to Xanthomonas oryzae pv. oryzae (Xoo), but the detailed resistance mechanism is unclear.
Ribulose
-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) activase (RCA) is an important enzyme that regulates photosynthesis by activating Rubisco. We have previously reported that
Xoo
infection induced the relocation of RCA from the chloroplast stroma to the thylakoid membrane in O. meyeriana, but the underlying regulating mechanism and physiological significance of this association remains unknown. In this study, "H
2
O
2
burst" with rapid and large increase in the amount of H
2
O
2
was found to be induced by Xoo invasion in the leaves of O. meyeriana. 3, 3-diaminobenzidine (DAB) and oxidative 2, 7-Dichlorodi-hydrofluorescein diacetate (H
2
DCFDA) staining experiments both showed that H
2
O
2
was generated in the chloroplast of O. meyeriana, and that this H
2
O
2
generation as well as Xoo resistance of the wild rice were dramatically dependent on light. H
2
O
2
, methyl viologen with light, and the xanthine-
xanthine oxidase
system all induced RCA to associate with the thylakoid membrane in vitro, which showed that H
2
O
2
could induce the relocation of RCA. In vitro experiments also showed that H
2
O
2
induced changes in both the RCA and thylakoid membrane that were required for them to associate and that this association only occurred in O. meyeriana and not in the susceptible cultivated rice. These results suggest that the association of RCA with the thylakoid membrane helps to protect the thylakoid membrane against oxidative damage from H
2
O
2
. Therefore, in addition to its universal function of activating Rubisco, RCA appears to play a novel role in the resistance of O. meyeriana to Xoo.
...
PMID:H
2
O
2
Induces Association of RCA with the Thylakoid Membrane to Enhance Resistance of Oryza meyeriana to Xanthomonas oryzae pv. oryzae. 3152 48
