The photolysis of lens fiber membranes

Dillon, James; Roy, Debdutta; Spector, Abraham

doi:10.1016/0014-4835(85)90093-4

Cited by 13 publications

(4 citation statements)

References 22 publications

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“…The studies reported here show that thiols can ameliorate inactivation of GAPDH induced by these 1 O 2 -generated peptide and protein peroxides, presumably by acting as sacrificial targets. This is in accord with the known rapid depletion of GSH and other thiols (both low-molecularmass and protein-bound) in photo-oxidized cells, and that maintenance of thiol levels offers protection [58][59][60][61]. Similarly, it has been shown that ascorbate and thiols can readily remove radiation-generated peptide and protein peroxides [26,27,29].…”

Section: Discussionsupporting

confidence: 59%

Inhibition of glyceraldehyde-3-phosphate dehydrogenase by peptide and protein peroxides generated by singlet oxygen attack

Morgan¹,

Dean²,

Davies³

2002

Eur J Biochem

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Reaction of certain peptides and proteins with singlet oxygen (generated by visible light in the presence of rose bengal dye) yields long-lived peptide and protein peroxides. Incubation of these peroxides with glyceraldehyde-3-phosphate dehydrogenase, in the absence of added metal ions, results in loss of enzymatic activity. Comparative studies with a range of peroxides have shown that this inhibition is concentration, peroxide, and time dependent, with H 2 O 2 less efficient than some peptide peroxides. Enzyme inhibition correlates with loss of both the peroxide and enzyme thiol residues, with a stoichiometry of two thiols lost per peroxide consumed. Blocking the thiol residues prevents reaction with the peroxide. This stoichiometry, the lack of metal-ion dependence, and the absence of electron paramagnetic resonance (EPR)-detectable species, is consistent with a molecular (nonradical) reaction between the active-site thiol of the enzyme and the peroxide. A number of low-molecular-mass compounds including thiols and ascorbate, but not Trolox C, can prevent inhibition by removing the initial peroxide, or species derived from it. In contrast, glutathione reductase and lactate dehydrogenase are poorly inhibited by these peroxides in the absence of added Fe 2+ -EDTA. The presence of this metal-ion complex enhanced the inhibition observed with these enzymes consistent with the occurrence of radicalmediated reactions. Overall, these studies demonstrate that singlet oxygen-mediated damage to an initial target protein can result in selective subsequent damage to other proteins, as evidenced by loss of enzymatic activity, via the formation and subsequent reactions of protein peroxides. These reactions may be important in the development of cellular dysfunction as a result of photo-oxidation.

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Section: Discussionsupporting

confidence: 59%

Inhibition of glyceraldehyde-3-phosphate dehydrogenase by peptide and protein peroxides generated by singlet oxygen attack

Morgan¹,

Dean²,

Davies³

2002

Eur J Biochem

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show abstract

“…The studies reported here show that thiols can ameliorate inactivation of GAPDH induced by these 1 O 2 ‐generated peptide and protein peroxides, presumably by acting as sacrificial targets. This is in accord with the known rapid depletion of GSH and other thiols (both low‐molecular‐mass and protein‐bound) in photo‐oxidized cells, and that maintenance of thiol levels offers protection [58–61]. Similarly, it has been shown that ascorbate and thiols can readily remove radiation‐generated peptide and protein peroxides [26,27,29].…”

Section: Discussionsupporting

confidence: 54%

Inhibition of glyceraldehyde‐3‐phosphate dehydrogenase by peptide and protein peroxides generated by singlet oxygen attack

Morgan¹,

Dean²,

Davies³

2002

European Journal of Biochemistry

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Reaction of certain peptides and proteins with singlet oxygen (generated by visible light in the presence of rose bengal dye) yields long-lived peptide and protein peroxides. Incubation of these peroxides with glyceraldehyde-3-phosphate dehy-drogenase, in the absence of added metal ions, results in loss of enzymatic activity. Comparative studies with a range of peroxides have shown that this inhibition is concentration, peroxide, and time dependent, with H 2 O 2 less efficient than some peptide peroxides. Enzyme inhibition correlates with loss of both the peroxide and enzyme thiol residues, with a stoichiometry of two thiols lost per peroxide consumed. Blocking the thiol residues prevents reaction with the per-oxide. This stoichiometry, the lack of metal-ion dependence, and the absence of electron paramagnetic resonance (EPR)-detectable species, is consistent with a molecular (nonradi-cal) reaction between the active-site thiol of the enzyme and the peroxide. A number of low-molecular-mass compounds including thiols and ascorbate, but not Trolox C, can prevent inhibition by removing the initial peroxide, or species derived from it. In contrast, glutathione reductase and lac-tate dehydrogenase are poorly inhibited by these peroxides in the absence of added Fe 2+-EDTA. The presence of this metal-ion complex enhanced the inhibition observed with these enzymes consistent with the occurrence of radical-mediated reactions. Overall, these studies demonstrate that singlet oxygen-mediated damage to an initial target protein can result in selective subsequent damage to other proteins, as evidenced by loss of enzymatic activity, via the formation and subsequent reactions of protein peroxides. These reactions may be important in the development of cellular dys-function as a result of photo-oxidation.

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“…However, in sarcoplasmic reticulum vesicles, UVB induces the photocleavage of Ca++-ATPase, rendering it immediately inactive (25). This susceptibility of the ATPase to oxidation and the fact that UV irradiation can induce protein crosslinking (27) in the lens invites speculation that UV probably is capable of oxidative inactivation of Ca++-ATPase. Photocleavage has not been demonstrated in the lens exposed to the UVB spectrum.…”

Section: Epithelium and Opacificationmentioning

confidence: 99%

The role of the lens epithelium in development of UV cataract

Hightower

1995

Current Eye Research

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In view of renewed interest in the lens epithelium as the initiation site for cataract development, it seemed timely to review recent studies which appear to establish UV damage in the lens epithelium as the cause of UV cataract. While UV photons can and do interact with lens proteins in the cortex and nucleus, experimental results from cultured lenses and tissue cultured epithelial cells also demonstrate both mutagenic and cytotoxic effects in the epithelium. This minireview examines UV-induced changes in lens physiology that appear to follow epithelial cell damage, including inactivation of critical enzymes of transport and metabolic processes. Changes in membrane function include altered cation transport, increased permeability, and altered biosynthesis. One potential scenario for the propagation of damage from the epithelium to the underlying fiber cells includes calcium elevation, an early event in cataract development and critical to many physiological processes.

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The photolysis of lens fiber membranes

Cited by 13 publications

References 22 publications

Inhibition of glyceraldehyde-3-phosphate dehydrogenase by peptide and protein peroxides generated by singlet oxygen attack

Inhibition of glyceraldehyde-3-phosphate dehydrogenase by peptide and protein peroxides generated by singlet oxygen attack

Inhibition of glyceraldehyde‐3‐phosphate dehydrogenase by peptide and protein peroxides generated by singlet oxygen attack

The role of the lens epithelium in development of UV cataract

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