Light quenching of fluorescence of aromatic amino acids

Arutyunyan, A. G.; L'vov, K.M.; Mnatsakanyan, A. O.; Oganesyan, V. A.; Shakhnazaryan, N V

doi:10.1007/bf00660434

Cited by 3 publications

(3 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most probably, the effect of BHB on preventing insulin glycation is due to BHB binding to glycation prone residues in protein to diminish the glycation susceptibility. In addition, proteins present their intrinsic fluorescence because of their main flourophore residues; tryptophan (Trp, W), tyrosine (Tyr, Y) and phenylalanine (Phe, F), but only Trp and Tyr are used experimentally because their quantum yields are high enough to give a good fluorescence signal [ 36 ]. In insulin as a special case, Tyr dominates the fluorescence excitation at 280 nm in the absence of Trp.…”

Section: Discussionmentioning

confidence: 99%

Protection by beta-Hydroxybutyric acid against insulin glycation, lipid peroxidation and microglial cell apoptosis

et al. 2015

View full text Add to dashboard Cite

BackgroundDiabetes mellitus is characterized jointly by hyperglycemia and hyperinsulinemia that make insulin more prone to be glycated and evolve insulin advanced glycation end products (Insulin- AGE). Here, we report the effect of beta-hydroxy butyrate (BHB) (the predominant ketone body) on the formation of insulin-AGE, insulin glycation derived liposomal lipid peroxidation and insulin-AGE toxicity in microglial cells.MethodsThe inhibitory effect of BHB was monitored as a result of insulin incubation in the presence of glucose or fructose using AGE-dependent fluorescence, Tyr fluorescence as well as anilinonaphthalenesulfonate (ANS) andthioflavin T (ThT) binding, and circular dichroism (CD) investigations. To study lipid peroxidation induced by insulin glycation, thiobarbituric acid (TBA) assay and thiobarbituric acid reactive substance (TBARS) monitoring were used. The effect of insulin–AGE on microglial viability was investigated by 3-(4, 5 dimethylthiazol-2-yl)—2, 5-diphenyltetrazoliumbromide (MTT) cell assay and Annexin V/propidium iodide (PI) staining.ResultsHere we are reporting the inhibitory effect of BHB on insulin glycation and generation of insulin-AGE as a possible explanation for insulin resistance. Moreover, the protective effect of BHB on consequential glycation derived liposomal lipid peroxidation as a causative event in microglial apoptosis is reported.ConclusionThe reduced insulin fibril formation, structural inertia to glycation involved conformational changes, anti-lipid peroxidation effect, and increasing microglia viability indicated the protective effect of BHB that disclose insight on the possible preventive effect of BHB on Alzheimer’s disease.

show abstract

Section: Discussionmentioning

confidence: 99%

Protection by beta-Hydroxybutyric acid against insulin glycation, lipid peroxidation and microglial cell apoptosis

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Intrinsic protein fluorescence is a sensitive technique that has been exploited in studying the structural, physicochemical, and functional properties of proteins (26). Proteins derive their intrinsic fluorescence from the chromophores phenylalanine, tyrosine, and tryptophan (27). Bovine insulin contains four Tyr and three Phe residues.…”

Section: Introductionmentioning

confidence: 99%

Tyrosine Autofluorescence as a Measure of Bovine Insulin Fibrillation

Bekard

Dunstan

2009

Biophysical Journal

121

113

View full text Add to dashboard Cite

The traditional approach to investigating the partial unfolding and fibrillation of insulin, and proteins at large, has involved use of the dyes 1-anilinonaphthalene-8-sulphonic acid (ANS) and Thioflavin T (ThT), respectively. We compare the kinetic profiles of ThT, ANS, light scattering, and intrinsic Tyr fluorescence during insulin fibrillation. The data reveal that the sequence of structural changes (dimers --> monomers --> partially unfolded monomers --> oligomeric aggregates --> fibrils) accompanying insulin fibrillation can be detected directly using intrinsic Tyr fluorescence. The results indicate that at least two distinguishable structural intermediates precede fibril development. There is no evidence of tyrosinate or dityrosine during insulin aggregation. Obtaining such critical information from the protein itself is complementary to existing aggregation probes and affords the advantage of directly examining structural changes that occur at the molecular level, providing concrete details of the early events preceding fibrillation.

show abstract

“…In the absence of Trp, Tyr dominates the absorption spectrum of insulin (when Phe and nonaromatic absorption are excluded) and provides basic information on the dynamics of structural reorganization in protein molecules. 34,35 Fig. 1 presents the insulin glycation (by glucose or fructose) induced structural alterations as a function of time, using intrinsic or extrinsic uorescence.…”

Section: Resultsmentioning

confidence: 99%