Photoluminescence of Aromatic Amino Acids, Synthetic Polypeptides, Proteins, and Cells
The photoluminescence of proteins is due to the component amino acids (intrinsic luminescence) or various prosthetic groups if such groups are present in the protein molecule. To investigate structure, one can also examine luminescence protein by means of artificially attached groups (dyes) in which the dye luminesces (secondary luminescence).
KeywordsQuantum Yield Fluorescence Spectrum Propylene Glycol Polypeptide Chain Tyrosine Residue
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- The luminescence of aliphatic amino acids [Rybac et al (1955); Dimartin et al (1957); Longin (1959); Douzou and Francq (1962)] and of the aromatic amino acids and proteins excited in spectral regions where there are no appreciable absorption bands [Steele and Szent-Györgyi (1957, 1958); Isenberg and Szent-Györgyi (1958); Fujimori (1960)] is interesting but still not well understood and will not be considered in this chapter.Google Scholar
- According to Vladimirov and Li Chin-ho (1962), the short-wave shifts of the fluorescence of tryptophan-containing proteins and tryptophan crystals in comparison with the free acid in solution are both due to a restriction of the vibrational degrees of freedom. The actual reason for the shift is thought to be hydrogen bonding between the tryptophan NH and adjacent acid groups.Google Scholar
- It is assumed that the “normal” tyrosine residues of ribonuclease are iodinated first [Donovan (1963)].Google Scholar
- Konev (1964) reports that changes in the quaternary structure are also reflected in changes of the fluorescence spectra, but these changes of the fluorescence intensity could be due to associated alterations in the secondary and tertiary structure.Google Scholar
- Konev and Lyskova (1965) found that the addition of urea to mitochondrial suspensions differing in respiration rate reduced the differences between the fluorescence intensities of these suspensions. This was regarded as direct proof of the fact that fluorescence intensity is influenced by the tertiary and quaternary structures of the protein, which are affected by urea. However, it is also possible that the above authors observed not a direct action of urea on the proteins responsible for the fluorescence but an indirect one, since in the concentrations used urea can cause swelling of the mitochondria.Google Scholar