Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers

Research output: Contribution to journalJournal articlepeer-review

Standard

Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers. / Zhao, Zichen; Poojary, Mahesha M.; Skibsted, Leif H.; Lund, Marianne N.

In: Journal of Agricultural and Food Chemistry, Vol. 68, No. 25, 2020, p. 6900-6909.

Research output: Contribution to journalJournal articlepeer-review

Harvard

Zhao, Z, Poojary, MM, Skibsted, LH & Lund, MN 2020, 'Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers', Journal of Agricultural and Food Chemistry, vol. 68, no. 25, pp. 6900-6909. https://doi.org/10.1021/acs.jafc.0c01760

APA

Zhao, Z., Poojary, M. M., Skibsted, L. H., & Lund, M. N. (2020). Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers. Journal of Agricultural and Food Chemistry, 68(25), 6900-6909. https://doi.org/10.1021/acs.jafc.0c01760

Vancouver

Zhao Z, Poojary MM, Skibsted LH, Lund MN. Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers. Journal of Agricultural and Food Chemistry. 2020;68(25):6900-6909. https://doi.org/10.1021/acs.jafc.0c01760

Author

Zhao, Zichen ; Poojary, Mahesha M. ; Skibsted, Leif H. ; Lund, Marianne N. / Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers. In: Journal of Agricultural and Food Chemistry. 2020 ; Vol. 68, No. 25. pp. 6900-6909.

Bibtex

@article{97cc354958b7477eb5b4c6ec6639d103,
title = "Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers",
abstract = "Photolytic cleavage of disulfide bonds in proteins by UV light will influence their structure and functionality. The present study aimed to investigate the efficiency of disulfide cleavage by UV-B light in a system without a protein backbone consisting of combinations of cystine (a disulfide) and tryptophan (Trp) or tyrosine (Tyr) under anaerobic and aerobic conditions and to identify oxidation products formed by UV-B light. Cystine was reduced to cysteine (Cys) almost with a 1:1 stoichiometry by photoexcited Trp for anaerobic equimolar aqueous solutions (each 200 μM; pH 7.0), while photoexcited Tyr provided lower concentrations of Cys. The calculation of apparent quantum yields allowed for a comparison between the efficiency of reactions and showed that formation of Cys from disulfide cleavage of cystine was more efficient by photoexcited Trp than by photoexcited Tyr and of cystine alone and that Trp was more sensitive to photodegradation than Tyr and cystine under both aerobic and anaerobic conditions. Increasing the ratio between cystine and Trp to a 1:2 ratio did not increase the efficiency of free thiol formation but caused a more efficient photodegradation of Trp. The free thiol formed from disulfide cleavage of cystine was further oxidized to other unidentified compounds. Trp oxidation products (3-hydroxykynurenine (3-OH-Kyn) and tryptamine) were only identified in minor concentrations following light exposure of cystine and Trp in 1:1 and 1:2 ratios under both aerobic and anaerobic conditions, indicating further photodegradation to unidentified compounds. 3,4-Dihydroxyphenylalanine (DOPA) was formed from the oxidation of Tyr in the illuminated samples of cystine and Tyr in a 1:1 ratio under both aerobic and anaerobic conditions.",
keywords = "disulfide bond cleavage, photo-oxidation, quantum yield, UV irradiation",
author = "Zichen Zhao and Poojary, {Mahesha M.} and Skibsted, {Leif H.} and Lund, {Marianne N.}",
year = "2020",
doi = "10.1021/acs.jafc.0c01760",
language = "English",
volume = "68",
pages = "6900--6909",
journal = "Journal of Agricultural and Food Chemistry",
issn = "0021-8561",
publisher = "American Chemical Society",
number = "25",

}

RIS

TY - JOUR

T1 - Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers

AU - Zhao, Zichen

AU - Poojary, Mahesha M.

AU - Skibsted, Leif H.

AU - Lund, Marianne N.

PY - 2020

Y1 - 2020

N2 - Photolytic cleavage of disulfide bonds in proteins by UV light will influence their structure and functionality. The present study aimed to investigate the efficiency of disulfide cleavage by UV-B light in a system without a protein backbone consisting of combinations of cystine (a disulfide) and tryptophan (Trp) or tyrosine (Tyr) under anaerobic and aerobic conditions and to identify oxidation products formed by UV-B light. Cystine was reduced to cysteine (Cys) almost with a 1:1 stoichiometry by photoexcited Trp for anaerobic equimolar aqueous solutions (each 200 μM; pH 7.0), while photoexcited Tyr provided lower concentrations of Cys. The calculation of apparent quantum yields allowed for a comparison between the efficiency of reactions and showed that formation of Cys from disulfide cleavage of cystine was more efficient by photoexcited Trp than by photoexcited Tyr and of cystine alone and that Trp was more sensitive to photodegradation than Tyr and cystine under both aerobic and anaerobic conditions. Increasing the ratio between cystine and Trp to a 1:2 ratio did not increase the efficiency of free thiol formation but caused a more efficient photodegradation of Trp. The free thiol formed from disulfide cleavage of cystine was further oxidized to other unidentified compounds. Trp oxidation products (3-hydroxykynurenine (3-OH-Kyn) and tryptamine) were only identified in minor concentrations following light exposure of cystine and Trp in 1:1 and 1:2 ratios under both aerobic and anaerobic conditions, indicating further photodegradation to unidentified compounds. 3,4-Dihydroxyphenylalanine (DOPA) was formed from the oxidation of Tyr in the illuminated samples of cystine and Tyr in a 1:1 ratio under both aerobic and anaerobic conditions.

AB - Photolytic cleavage of disulfide bonds in proteins by UV light will influence their structure and functionality. The present study aimed to investigate the efficiency of disulfide cleavage by UV-B light in a system without a protein backbone consisting of combinations of cystine (a disulfide) and tryptophan (Trp) or tyrosine (Tyr) under anaerobic and aerobic conditions and to identify oxidation products formed by UV-B light. Cystine was reduced to cysteine (Cys) almost with a 1:1 stoichiometry by photoexcited Trp for anaerobic equimolar aqueous solutions (each 200 μM; pH 7.0), while photoexcited Tyr provided lower concentrations of Cys. The calculation of apparent quantum yields allowed for a comparison between the efficiency of reactions and showed that formation of Cys from disulfide cleavage of cystine was more efficient by photoexcited Trp than by photoexcited Tyr and of cystine alone and that Trp was more sensitive to photodegradation than Tyr and cystine under both aerobic and anaerobic conditions. Increasing the ratio between cystine and Trp to a 1:2 ratio did not increase the efficiency of free thiol formation but caused a more efficient photodegradation of Trp. The free thiol formed from disulfide cleavage of cystine was further oxidized to other unidentified compounds. Trp oxidation products (3-hydroxykynurenine (3-OH-Kyn) and tryptamine) were only identified in minor concentrations following light exposure of cystine and Trp in 1:1 and 1:2 ratios under both aerobic and anaerobic conditions, indicating further photodegradation to unidentified compounds. 3,4-Dihydroxyphenylalanine (DOPA) was formed from the oxidation of Tyr in the illuminated samples of cystine and Tyr in a 1:1 ratio under both aerobic and anaerobic conditions.

KW - disulfide bond cleavage

KW - photo-oxidation

KW - quantum yield

KW - UV irradiation

U2 - 10.1021/acs.jafc.0c01760

DO - 10.1021/acs.jafc.0c01760

M3 - Journal article

C2 - 32437144

AN - SCOPUS:85087097351

VL - 68

SP - 6900

EP - 6909

JO - Journal of Agricultural and Food Chemistry

JF - Journal of Agricultural and Food Chemistry

SN - 0021-8561

IS - 25

ER -

ID: 244527091