title: Fluorescence of proteins induced by two-photon absorption.
abstract: At room temperature, the UV fluorescence of trypsin, thyroglobulin, hemoglobin and albumin are observed; these molecules undergo two-photon absorption when they are excited with the radiation of a frequency-duplicated Q-switched Nd:YAG laser. It is shown that the fluorescence of these proteins comes from the tryptophan residues and that it has a red shift of about 20 nm relative to the one-photon fluorescence. We suggest that the weak emission from tyrosine arises from the forbidden two-photon transition. The influence of concentration on the fluorescence of hemoglobin and tryptophan is discussed. The two-photon absorption cross-sections are estimated.
authors.affiliation: Anhui Institute of Optics and Fine Mechanics, Academia Sinica, Hefei, China.
authors.forename: Y W
authors.initials: YW
authors.lastname: Xu
authors.forename: J R
authors.initials: JR
authors.lastname: Zhang
authors.forename: Y M
authors.initials: YM
authors.lastname: Deng
authors.forename: L K
authors.initials: LK
authors.lastname: Hui
authors.forename: S P
authors.initials: SP
authors.lastname: Jiang
authors.forename: S H
authors.initials: SH
authors.lastname: Lian
mesh_terms: D006454:Hemoglobins; D011487:Protein Conformation; D011506:Proteins; D011827:Radiation; D012709:Serum Albumin; D013050:Spectrometry, Fluorescence / Q000379:methods; D013954:Thyroglobulin; D014357:Trypsin; D014364:Tryptophan
chemical_list: D006454:Hemoglobins; D011506:Proteins; D012709:Serum Albumin; D014364:Tryptophan; D013954:Thyroglobulin; D014357:Trypsin