Fluorescence of proteins induced by two-photon absorption.
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.
Xu
Y W
YW
Anhui Institute of Optics and Fine Mechanics, Academia Sinica, Hefei, China.
Zhang
J R
JR
Deng
Y M
YM
Hui
L K
LK
Jiang
S P
SP
Lian
S H
SH
D006454:Hemoglobins; D011487:Protein Conformation; D011506:Proteins; D011827:Radiation; D012709:Serum Albumin; D013050:Spectrometry, Fluorescence / Q000379:methods; D013954:Thyroglobulin; D014357:Trypsin; D014364:Tryptophan
D006454:Hemoglobins; D011506:Proteins; D012709:Serum Albumin; D014364:Tryptophan; D013954:Thyroglobulin; D014357:Trypsin