Probing the Effect of Ag 2 S Quantum Dots on Human Serum Albumin Using Spectral Techniques

The understanding of the interaction between protein and quantum dots (QDs) has significant implications for biological applications of QDs. Herein, we studied the effect of Ag 2 S QDs on human serum albumin (HSA) using UV-Vis absorption spectra and fluorescence spectroscopy and found that the fluorescence intensity of HSA was gradually decreased with increasing Ag 2 S QDs concentrations. By using the Stern-Volmer equation for the fluorescence quenching constant ( SV ) of the response of Ag 2 S QDs to HSA as well as thermodynamic equations, the values of thermodynamic enthalpy change (Δ ), entropy change (Δ ), and free energy change (Δ ) were calculated to be −10.79 KJ⋅mol −1 , 37.80 J⋅mol −1 ⋅K −1 , and −22.27 KJ⋅mol −1 , respectively. The results indicate that Ag 2 S QDs exert an obvious static fluorescence quenching effect on HSA and electrostatic interaction plays a key role in the binding process. Furthermore, Raman spectral analysis reveals that Ag 2 S QDs alter the external environment of tyrosine and tryptophan or the C-H bending of HSA but not the -helical content

Probing the Effect of Ag 2

The understanding of the interaction between protein and quantum dots (QDs) has significant implications for biological applications of QDs. Herein, we studied the effect of Ag2S QDs on human serum albumin (HSA) using UV-Vis absorption spectra and fluorescence spectroscopy and found that the fluorescence intensity of HSA was gradually decreased with increasing Ag2S QDs concentrations. By using the Stern-Volmer equation for the fluorescence quenching constant (KSV) of the response of Ag2S QDs to HSA as well as thermodynamic equations, the values of thermodynamic enthalpy change (ΔHθ), entropy change (ΔSθ), and free energy change (ΔGθ) were calculated to be −10.79 KJ·mol−1, 37.80 J·mol−1·K−1, and −22.27 KJ·mol−1, respectively. The results indicate that Ag2S QDs exert an obvious static fluorescence quenching effect on HSA and electrostatic interaction plays a key role in the binding process. Furthermore, Raman spectral analysis reveals that Ag2S QDs alter the external environment of tyrosine and tryptophan or the C-H bending of HSA but not the α-helical content

Mutations of von Hippel-Lindau Tumor-Suppressor Gene and Congenital Polycythemia

The von Hippel-Lindau (pVHL) protein plays an important role in hypoxia sensing. It binds to the hydroxylated hypoxia-inducible factor 1α (HIF-1α) and serves as a recognition component of an E3-ubiquitin ligase complex. In hypoxia or secondary to a mutated VHL gene, the nondegraded HIF-1α forms a heterodimer with HIF-β and leads to increased transcription of hypoxia-inducible genes, including erythropoietin (EPO). The autosomal dominant cancer-predisposition von Hippel-Lindau (VHL) syndrome is due to inheritance of a single mutated allele of VHL. In contrast, we recently showed that homozygous germline 598C→T VHL mutation leads to Chuvash polycythemia (CP). We subsequently found VHL mutations in three unrelated individuals unaffected with CP, one of whom was compound heterozygous for the 598C→T mutation and another VHL mutation. We now report seven additional polycythemic patients with VHL mutations in both alleles. Two Danish siblings and another American boy were homozygous for the VHL 598C→T mutation. Three unrelated white Americans were compound heterozygotes for 598C→T and another VHL mutation, 562C→G in two and 574C→T in the third. Additionally, a Croatian boy was homozygous for a 571C→G VHL mutation, the first example of homozygous VHL germline mutation causing polycythemia, other than the VHL 598C→T mutation. We have not observed VHL syndrome–associated tumors in polycythemic subjects or their heterozygous relatives; however, this will need to be evaluated by longitudinal studies. Over all, we found that up to half of the consecutive patients with apparent congenital polycythemia and increased serum Epo we have examined have mutations of both VHL alleles. Those findings, along with reports of CP, underscore that VHL mutations are the most frequent cause of congenital polycythemia and define a new class of polycythemic disorder, polycythemias due to augmented hypoxia sensing

Silver lining to a climate crisis in multiple prospects for alleviating crop waterlogging under future climates

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