{"title":"Photoexcitation dynamics of azide ion bound ferric myoglobin probed by femtosecond infrared spectroscopy","authors":"Seongchul Park, Jooyoung Kim, Manho Lim","doi":"10.1002/bkcs.12803","DOIUrl":null,"url":null,"abstract":"<p>The photoexcitation dynamics of N<sub>3</sub><sup>−</sup>-bound ferric myoglobin (MbN<sub>3</sub>) were investigated after exciting MbN<sub>3</sub> in D<sub>2</sub>O at 283 K with a 575 nm pulse by probing the anti-symmetric stretching mode of the azide. Global fitting of the overall time-resolved spectra revealed that thermal relaxation of two stretching bands proceeded with a time constant of 6 ps, and that a new absorption band formed and decayed with time constants of 0.6 and 23 ps, respectively. The new absorption near 2040 cm<sup>−1</sup> was attributed to the high-spin species 2.4 kJ/mol above the low-spin species, as the excited low-spin relaxes thermally via the high-spin species. However, this absorption could also arise from deligated N<sub>3</sub>̄ remaining within the protein. The decay of this absorption can be interpreted as either spin transition of the high-spin species into the low-spin species or geminate recombination of the dissociated N<sub>3</sub>̄. The implications of both interpretations are discussed.</p>","PeriodicalId":54252,"journal":{"name":"Bulletin of the Korean Chemical Society","volume":"45 2","pages":"171-177"},"PeriodicalIF":1.7000,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bulletin of the Korean Chemical Society","FirstCategoryId":"92","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/bkcs.12803","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The photoexcitation dynamics of N3−-bound ferric myoglobin (MbN3) were investigated after exciting MbN3 in D2O at 283 K with a 575 nm pulse by probing the anti-symmetric stretching mode of the azide. Global fitting of the overall time-resolved spectra revealed that thermal relaxation of two stretching bands proceeded with a time constant of 6 ps, and that a new absorption band formed and decayed with time constants of 0.6 and 23 ps, respectively. The new absorption near 2040 cm−1 was attributed to the high-spin species 2.4 kJ/mol above the low-spin species, as the excited low-spin relaxes thermally via the high-spin species. However, this absorption could also arise from deligated N3̄ remaining within the protein. The decay of this absorption can be interpreted as either spin transition of the high-spin species into the low-spin species or geminate recombination of the dissociated N3̄. The implications of both interpretations are discussed.
期刊介绍:
The Bulletin of the Korean Chemical Society is an official research journal of the Korean Chemical Society. It was founded in 1980 and reaches out to the chemical community worldwide. It is strictly peer-reviewed and welcomes Accounts, Communications, Articles, and Notes written in English. The scope of the journal covers all major areas of chemistry: analytical chemistry, electrochemistry, industrial chemistry, inorganic chemistry, life-science chemistry, macromolecular chemistry, organic synthesis, non-synthetic organic chemistry, physical chemistry, and materials chemistry.