Fluorescence studies on tryptophan and sulfhydryl group changes of bovine lens crystallins in a photodynamic system

Andley, Usha P.; Chapman, Susan F.; Chylack, Leo T.

doi:10.3109/00365529209067643

Cited by 3 publications

(16 citation statements)

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“…These sensitizers included ribo¯avin (Andley, Chapman and Chylack, 1985), Rose Bengal (Balasubramanian, Du and Zigler, 1990), porphyrins (Roberts et al, 1991) and either methylene blue or formylkynurenine (Mandal, Bose and Chakrabarti, 1986;Ichijima and Iwata, 1987), all of which are capable of producing singlet oxygen in response to UVR light. These were accurate models, in that crude protein preparations from aged lenses also produced singlet oxygen when irradiated with UVA light (Zigler and Goosey, 1981;Linetsky and Ortwerth, 1997).…”

Section: Discussionmentioning

confidence: 99%

Studies on Singlet Oxygen Formation and UVA Light-mediated Photobleaching of the Yellow Chromophores in Human Lenses

Ortwerth

Chemoganskiy

Olesen

2002

Experimental Eye Research

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Section: Discussionmentioning

confidence: 99%

Studies on Singlet Oxygen Formation and UVA Light-mediated Photobleaching of the Yellow Chromophores in Human Lenses

Ortwerth

Chemoganskiy

Olesen

2002

Experimental Eye Research

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“…Calf lens crystallins (a-, Plr-, PLand y-) were isolated and purified from calf cortices using a Sephacryl S-200 column, as described previously ( Andley e t a / . , 1982: Andley andChylack. 1986).…”

Section: Moteriulsmentioning

confidence: 99%

“…Irradiation of crystallins. The crystallins were irradiated in the presence of the photosensitizer methylene blue as described previously (Andley et a / . , 1985).…”

Section: Moteriulsmentioning

confidence: 99%

“…Conformational aspects of normal lens crystallins have been reported (Liang and Chakrabarti. 1982;Andley et al, 1982;Liang et al, 1985b). The effect of near-UV light (300 nm) has recently shown that there are significant changes in the conformation (tertiary structure).…”

Section: Introductionmentioning

confidence: 99%

“…The effect of near-UV light (300 nm) has recently shown that there are significant changes in the conformation (tertiary structure). involving tryptophan and cysteine residues of a-crystallin (Andley e f id., 1984;Andley and Chylack, 1986). These studies were done using circular dichroism (CD) and fluorescence methods.…”

Section: Introductionmentioning

confidence: 99%

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Conformational Changes of Bovine Lens Crystallins in a Photodynamic System

Andley

Chapman

1986

Photochem & Photobiology

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Abstract— Conformational changes of bovine lens crystallins in a photodynamic system generating singlet oxygen, have been investigated. The formation of intersubunit crosslinks was observed in all three classes (α‐, β and γ‐) of crystallins by irradiation in the presence of the photosensitizer methylene blue. Near‐UV circular dichroism (CD) spectra of the crystallins were significantly altered by irradiation under these conditions, indicating changes in tertiary structure but the far‐UV CD remained unchanged suggesting that the secondary structure ((β‐sheet conformation) remains unchanged. Significant changes in the absorption and fluorescence spectra were also observed. Measurement of total sulfhydryl content showed a decrease of 27%, 50% and 37% for α‐, β‐ and γ‐crystallins respectively, after irradiation. Fluorescence lifetime measurements of N‐iodoacetyl‐N'‐(5‐sulfo‐l‐naphthyl)ethylenediamine‐labeled crystallins showed a significant decrease of the lifetime of the major decay components of the label bound to sulfhydryl groups of α‐ and γ‐crystallins, but showed no change in the microenvironment of the sulfhydryl groups of β‐crystallin. The results are consistent with the microenvironments of the tryptophan and sulfhydryl groups predicted from sequence studies.

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Small molecules, both dietary and endogenous, influence the onset of lens cataracts

Barnes

Quinlan

2017

Experimental Eye Research

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How the lens ages successfully is a lesson in biological adaption and the emergent properties of its complement of cells and proteins. This living tissue contains some of the oldest proteins in our bodies and yet they remain functional for decades, despite exposure to UV light, to reactive oxygen species and all the other hazards to protein function. This remarkable feat is achieved by a shrewd investment in very stable proteins as lens crystallins, by providing a reservoir of ATP-independent protein chaperones unequalled by any other tissue and by an oxidation-resistant environment. In addition, glutathione, a free radical scavenger, is present in mM concentrations and the plasma membranes contain oxidation-resistant sphingolipids, so what compromises lens function as it ages? In this review, we examine the role of small molecules in the prevention or causation of cataracts, including those associated with diet, metabolic pathways and drug therapy (steroids).

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Fluorescence studies on tryptophan and sulfhydryl group changes of bovine lens crystallins in a photodynamic system

Cited by 3 publications

References 0 publications

Studies on Singlet Oxygen Formation and UVA Light-mediated Photobleaching of the Yellow Chromophores in Human Lenses

Studies on Singlet Oxygen Formation and UVA Light-mediated Photobleaching of the Yellow Chromophores in Human Lenses

Conformational Changes of Bovine Lens Crystallins in a Photodynamic System

Small molecules, both dietary and endogenous, influence the onset of lens cataracts

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