Mechanism of Inactivation of Enzyme Proteins by Ultraviolet Light

McLaren, A. D.; Luse, R. A.

doi:10.1126/science.134.3482.836

Cited by 71 publications

(16 citation statements)

References 6 publications

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“…UV radiation damages cells by interfering with synthesis of macromolecules, among which nucleic acid synthesis is the prime target (Murphy 1975, Giese 1976, The alteration of nucleic acids by UV radiation would ultimately lead to changes in catalytic and structural proteins which themselves absorb UV radiation and could therefore be directly affected (McLaren andLuse 1961, Giese 1976). Since about 75% of protein in green leaves is in the chioroplasts, leaves cannot suffer much protein loss without harm to their photosynthetic organelies (Campbell 1975).…”

Section: Discussionmentioning

confidence: 99%

Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C₃ and C₄ crop plants

Allen

Garrard

1982

Physiologia Plantarum

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Effects of increased UV‐B radiation on activities of primary photosynthetic carboxylating enzymes and on contents of soluble proteins were studied in soybean (Glycine max [L.] Merr. cv. Bragg), pea (Pisum sativum L. cv. Little Marvel), tomato (Lycopersicon esculentum L. cv. Rutgers), and sweet corn (Zea mays L. cv. Golden Cross Bantam). The purpose was to evaluate the responses of agronomic crops to increases in solar UV‐B radiation. Plants were grown and exposed under greenhouse conditions for 6 h daily to supplemental UV‐B radiation which was provided by Westinghouse FS‐40 fluorescent sun lamps filtered with 0.127‐mm film of cellulose acetate (UV‐B treated) or Mylar S (Mylar control). Three UV‐B levels were tested: 1.09 (treatment T1), 1.36 (treatment T2), and 1.83 (treatment T3) UV‐Bseu where 1 UV‐Bseu equals 16.0 mW‐m2 weighted by EXP‐[(λ‐265)/21]2. These UV‐B levels corresponded to 6%,21%, and 36%, respectively, of decrease in stratospheric ozone content, based on the interpolations of UV‐B irradiances at a solar elevation angle of 60°. Leaves of plants of soybean, pea, and tomato exposed to UV‐B radiation were generally low in RuBP carboxylase activity. On a fresh weight basis, all three UV‐B radiation levels significantly reduced the enzyme activity in soybean and pea, whereas tomato plants showed significant reduction in RuBP carboxylase activity only when exposed to 1.83 and 1.36 UV‐Bseu. An apparent decrease in soluble proteins was observed in leaf extracts of soybean and pea plants exposed to 1.36 and 1.83 UV‐Bseu whereas higher amounts of proteins were detected in leaves of tomato plants grown under UV‐B radiation. Leaves of sweet corn plants grown under Mylar control were low in PEP carboxylase activity and proteins as compared with those of control plants receiving no supplemental UV and UV‐B treatment. Activities of PEP carboxylase in crode extracts from leaves of sweet corn were significantly suppressed under 1.36 and 1.83 UV‐Bseu as compared with the no UV control. Some stimulation of PEP carboxylase activity was observed in corn plants exposed to 1.09 UV‐Bseu.

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Section: Discussionmentioning

confidence: 99%

Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C₃ and C₄ crop plants

Allen

Garrard

1982

Physiologia Plantarum

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“…1981). generalized changes in enzymatic activity (McLaren and Luse, 1961;Augenstein and Riley, 1964;Vladimirov et al, 1070;Grossweiner, 1976 and1984), and/ or changes in mitochondria1 activity (Kashket and Brodie. 1'163;Ninneman et id.. lY70;Ninneman, 1973;Werben et al, 1974: Crocket andLawwill.…”

Section: Signi/icuriccmentioning

confidence: 99%

Effect of Ultraviolet Radiation on the Energy Metabolism of the Corneal Epithelium of the Rabbit

Lattimore

1989

Photochem & Photobiology

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The present research was directed at quantifying possible alterations in corneal epithelial metabolic activity secondary to in vivo exposure to ultraviolet radiation (UVR). Microfluorometric energy metabolite assays on microgram (microgram) sized, freeze-dried tissue samples were used as an in vitro means of assessing overall metabolic activity in the epithelium of control rabbit corneas and in the epithelium of UVR-exposed rabbit corneas 2 min after discontinuation of exposure. The specific assays were for glucose, glycogen, adenosine triphosphate (ATP), and phosphocreatine (PCr). The radiant exposures were kept constant at 0.05 J cm-2 for all UVR wavelengths utilized (290, 300, 310 and 360 nm). Experimental UVR exposure conditions served to increase epithelial glucose and glycogen concentrations. Although the epithelial ATP concentrations were unchanged, the epithelial PCr concentrations (a high energy phosphate bond reservoir) decreased as a result of UVR exposure. Overall, the data demonstrate a decrease in corneal epithelial metabolic activity, which may be wavelength-dependent, as a result of UVR exposure. It is suggested that immediate metabolic stress can be responsible for the pattern of epithelial cell loss seen in photokeratitis.

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“…The special importance of cystine residues was suggested by the correlation of Setlow[ 11 showing that the inactivation quantum yield for 1 1 enzymes is an approximate linear function of the half-cystine content. This approach was extended by McLaren and Luse [2,3] who proposed that each chromophoric residue (principally cystine and the aromatics) contributes independently to inactivation according to its absorption coefficient and the quantum yield for photochemical destruction of the residue. The application of this theory (which has been referred to as "McLaren's Rule") gives fair agreement with experiment for a number of enzymes [4,5].…”

Section: Introductionmentioning

confidence: 99%

Flash Photolysis and Inactivation of Aqueous Lysozyme*

Grossweiner

Usui

1971

Photochem & Photobiology

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Flash photolysis of aqueous lysozyme has shown that the initial photochemical products are photo-oxidized tryptophan residues ( A , , , = 500 nm), hydrated electrons (Amax = 720 nm), and the cystine residue electron adduct ( A , , , = 420 nm). Comparisons with mixtures of the chromophoric amino acids show that 1 to 2 tryptophan residues provide electrons at a quantum yield of 0.018 (25 per cent). Part of the ejected electrons are captured by cystine residues via a short-range, intramolecular process with essentially unit efficiency. The remainder become hydrated and back react with oxidized tryptophan residues before sec. The cystine residue electron adduct decays with 2 msec halftime (25°C) and 1.5 kcal/mole activation energy. The surviving oxidized tryptophan residues decay with a comparable time constant in a hydroxyl ion catalyzed process. In acid solutions the oxidized tryptophan residue and long-lived H atom adduct are observed (A,,, = 380 nm). The quantum yield of lysozyme inactivation induced by xenon Rash irradiation above 250 nm is 0.023 (20 per cent), which is not sensitive to oxygen or pH. Comparison to the primary photochemical reactions indicates that electron ejection from the essential tryptophan residues inactivates the enzyme, irrespective of the electron trap and subsequent reactions. On the basis of the structure and supporting information it is proposed that the tryptophan residues of the active site are involved. Direct disruption of cystine residues does not contribute more than 10 per cent to the inactivation quantum yield in this wavelength region. Lysozyme inactivation may differ from other enzymes because the chromophores include essential residues located in the active center.

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Mechanism of Inactivation of Enzyme Proteins by Ultraviolet Light

Cited by 71 publications

References 6 publications

Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C₃ and C₄ crop plants

Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C₃ and C₄ crop plants

Effect of Ultraviolet Radiation on the Energy Metabolism of the Corneal Epithelium of the Rabbit

Flash Photolysis and Inactivation of Aqueous Lysozyme*

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Mechanism of Inactivation of Enzyme Proteins by Ultraviolet Light

Cited by 71 publications

References 6 publications

Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C3 and C4 crop plants

Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C3 and C4 crop plants

Effect of Ultraviolet Radiation on the Energy Metabolism of the Corneal Epithelium of the Rabbit

Flash Photolysis and Inactivation of Aqueous Lysozyme*

Contact Info

Product

Resources

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Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C₃ and C₄ crop plants

Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C₃ and C₄ crop plants