Fluorescence kinetics of Trp-Trp dipeptide and its derivatives in water via ultrafast fluorescence spectroscopy

  • Menghui Jia
  • , Hua Yi
  • , Mengfang Chang
  • , Xiaodan Cao
  • , Lei Li
  • , Zhongneng Zhou
  • , Haifeng Pan
  • , Yan Chen
  • , Sanjun Zhang*
  • , Jianhua Xu
  • *Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Ultrafast fluorescence dynamics of Tryptophan-Tryptophan (Trp-Trp/Trp2) dipeptide and its derivatives in water have been investigated using a picosecond resolved time correlated single photon counting (TCSPC) apparatus together with a femtosecond resolved upconversion spectrophotofluorometer. The fluorescence decay profiles at multiple wavelengths were fitted by a global analysis technique. Nanosecond fluorescence kinetics of Trp2, N-tert-butyl carbonyl oxygen-N′-aldehyde group-l-tryptophan-l-tryptophan (NBTrp2), l-tryptophan-l-tryptophan methyl ester (Trp2Me), and N-acetyl-l-tryptophan-l-tryptophan methyl ester (NATrp2Me) exhibit multi-exponential decays with the average lifetimes of 1.99, 3.04, 0.72 and 1.22 ns, respectively. Due to the intramolecular interaction between two Trp residues, the "water relaxation" lifetime was observed around 4 ps, and it is noticed that Trp2 and its derivatives also exhibit a new decay with a lifetime of ∼100 ps, while single-Trp fluorescence decay in dipeptides/proteins shows 20-30 ps. The intramolecular interaction lifetime constants of Trp2, NBTrp2, Trp2Me and NATrp2Me were then calculated to be 3.64, 0.93, 11.52 and 2.40 ns, respectively. Candidate mechanisms (including heterogeneity, solvent relaxation, quasi static self-quenching or ET/PT quenching) have been discussed.

Original languageEnglish
Pages (from-to)243-248
Number of pages6
JournalJournal of Photochemistry and Photobiology B: Biology
Volume149
DOIs
StatePublished - 23 Jun 2015
Externally publishedYes

Keywords

  • Decay associated spectra (DAS)
  • Electron/proton transfer (ET/PT)
  • Quasi static self-quenching (QSSQ)
  • Time resolved fluorescence
  • Tryptophan dipeptides

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