One-and two-photon ionization of aqueous tryptophan by the harmonics of the Nd laser

Finnström, Bengt; Tfibel, F.; Lindqvist, Lars

doi:10.1016/0009-2614(80)80172-2

Cited by 28 publications

(5 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, in protein systems containing tyrosine and tryptophan, the principal products of UV-induced photochemical reactions are phenoxyl (from tyrosine) and tryptophanyl radicals, which can change further photochemically. 20,21,[23][24][25] In peptide systems containing both tryptophan and tyrosine, the formation of tryptophanyl radicals m ay be a precursor to phenoxyl radical formation. 23 The effect of 250 nm light on double-stranded DNA depends on the speci c sequence of nucleotides comprising the DNA and the exibility of the DNA at the photoproduct formation site.…”

Section: Discussionmentioning

confidence: 99%

Effects of Freeze-Thaw and Photobleaching on the Ultraviolet Resonance Raman Spectra of Human Colon Biopsies

et al. 2001

View full text Add to dashboard Cite

We studied the effects of sample freezing and thawing, laser fluence, temperature, and oxygen on the ultraviolet resonance Raman (UVRR) spectra of human colon biopsies at 251 nm excitation. We show that the total adenylate content of the tissue decreases as a result of freezing and subsequent thawing to room temperature. We also show that photobleaching is the result of oxidative as well as thermal damage. Photobleaching consisted of a decrease in the intensity of the purine spectral bands and broadening and intensity increase of the aromatic amino acid bands. Both bio- and photodegradation of the tissue can be minimized by keeping the biopsy samples refrigerated during testing and the laser fluence under 0.2 mJ/μm2. Unlike amino acid photobleaching, purine photobleaching was also greatly reduced by placing the samples in an argon atmosphere. Sample storage could be achieved by refrigerating the fresh specimens and testing them within 30 h of surgical resection, without freezing. Alternatively, the fresh specimens could be snap-frozen in liquid nitrogen, then thawed and tested for up to 30 min. Altogether, these studies can be utilized to guide future experimental design and data interpretation during ultraviolet spectroscopy of biological tissues.

show abstract

Section: Discussionmentioning

confidence: 99%

Effects of Freeze-Thaw and Photobleaching on the Ultraviolet Resonance Raman Spectra of Human Colon Biopsies

et al. 2001

View full text Add to dashboard Cite

show abstract

“…These effects decrease in the presence of a singlet quencher and the biphotonic nature of the process becomes apparent. It is interesting to note that in the intramolecular analogous case of tryptophan, a quadratic dependence on laser intensity was found (Finnstrom et al, 1980). The quenching effect of glycine, proline and hydroxy proline on the photoionization were determined by the initial slopes of plots such as those of Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The curves in Fig. 3 show a negative curvature, which can be due to several factors, among them a biphotonic process from the triplet itself (Finnstrom et at., 1980), or depopulation of the ground state (Lachish et al, 1976) and/or the excited singlet. In any case it is clearly shown that previous studies could have underestimated the triplet formation *In a recent review (Creed, 1984) a compilation of experimental results for +eG for indole is given.…”

Section: Resultsmentioning

confidence: 99%

“…Some results suggest that the monophotonic photoionization at 265 nm of indole derivatives arises from a non-relaxed prefluorescent state (Grossweiner et Amouyal et a/., 1982). Other workers found that at high laser intensities there is a contribution to the photoionization from a biphotonic process (Finnstrom et al, 1980), even when a linear relationship is found between electron yield and laser intensity (Klein et a/., 1981). In a ~~ Abbreviations: In indole; AA, amino acids; e & hydrated electron; Ini, indole cation radical; 'In*, indole excited singlet: 'In*, indole triplet.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Laser Flash Photolysis of Indole in the Presence of Amino Acids

Previtali

1984

Photochem & Photobiology

View full text Add to dashboard Cite

The laser flash photolysis of indole at 265 nm in the presence of glycine, proline and hydroxy proline was studied. The relative yields of c aq, triplet state, and indole cation radical were determined in the absence and in the presence of the amino acids. The yields were determined as a function of laser intensity and the values at very low intensity were compared with the fluorescence quenching results. It was concluded that in these conditions the photoionization of indole occurs via the fluorescent state. From the curves of triplet yield vs laser intensity, the triplet quantum yield extrapolated at low laser intensity was obtained, φr = 0.55 φ 0.05, relative to the literature value of 0.15 for φeag. This gives φF+φeaq= 1.0 ± 0.1 at room temperature. When proline and hydroxy proline were used as singlet quenchers, the yield of In was greater than the yield of caq. This was considered as evidence that a fraction of the quenching processes leads to complete electron transfer from indole to the amino acids.

show abstract

“…* To whom correspondence should be addressed. The photophysics of Trp have been extensively studied in aqueous solution (Bent and Hayon, 1975;Finnstrom et a / . , 1980;Grossweiner et al.…”

Section: Introductionmentioning

confidence: 99%

Photosensitization of Methyl Linoleate Oxidation by Tryptophan in Peptides

Kochevar

Yoon

1983

Photochem & Photobiology

View full text Add to dashboard Cite

The ability of tryptophan in peptides to photosensitize the oxidation of methyl linoleate (ML) was evaluated. Purified ML was irradiated (λ > 270 nm) alone or in the presence of a tryptophan‐containing peptide in ethanol solution. Oxidation was monitored by measuring the dienc hydroperoxides formed from ML by high performance liquid chromatography. N‐acetylphenylalanyltryptophan (NAPT) and N‐acetyltryptophan were about 2‐fold more effective as photosensitizers than leucyltryptophan and tryptophylleucine. N‐acetylphenylalanyltryptophan photolyzed in ethanol to form multiple photoproducts including N‐formylkynurenine‐type compounds. However, the NAPT photoproducts did not photosensitize the oxidation of ML and N‐formylkynurenine was about 8% as effective as NAPT. Sodium azide partially quenched the photooxidation sensitized by NAPT.

show abstract

One-and two-photon ionization of aqueous tryptophan by the harmonics of the Nd laser

Cited by 28 publications

References 19 publications

Effects of Freeze-Thaw and Photobleaching on the Ultraviolet Resonance Raman Spectra of Human Colon Biopsies

Effects of Freeze-Thaw and Photobleaching on the Ultraviolet Resonance Raman Spectra of Human Colon Biopsies

Laser Flash Photolysis of Indole in the Presence of Amino Acids

Photosensitization of Methyl Linoleate Oxidation by Tryptophan in Peptides

Contact Info

Product

Resources

About