Fluorometric investigation of the interaction of bovine serum albumin with surfactants and 6-mercaptopurine.

Fluorescence quenching in solutions of bovine serum albumin has been investigated in the presence of 6-mercaptopurine and ionic surfactants. Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of bovine serum albumin by 6-mercaptopurine was dynamic quenching mechanism. The Stern-Volmer quenching model has been successfully applied, and the activation energy of the interaction between 6-mercaptopurine and bovine serum albumin as much as 4.26 kJ mol(-1) was calculated. The distance r between donor (bovine serum albumin) and acceptor (6-mercaptopurine) was obtained according to fluorescence resonance energy transfer (FRET). The result of synchronous fluorescence spectra shows that the conformation of bovine serum albumin has been changed at the present of 6-mercaptopurine.

Interaction of colchicine with human serum albumin investigated by spectroscopic methods.

We investigated the interaction between colchicine and human serum albumin (HSA) by fluorescence and UV-vis absorption spectroscopy. In the mechanism discussion, it was proved that the fluorescence quenching of HSA by colchicine is a result of the formation of colchicines-HSA complex; van der Waals interactions and hydrogen bonds play a major role in stabilizing the complex. The modified Stern-Volmer quenching constant K(a) and corresponding thermodynamic parameters deltaH, deltaG, deltaS at different temperatures were calculated. The distance r between donor (Trp214) and acceptor (colchicine) was obtained according to fluorescence resonance energy transfer (FRET).

Helicobacter pylori promotes invasion and metastasis of gastric cancer cells through activation of AP-1 and up-regulation of CACUL1.

Infection with Helicobacter pylori is important in the development and progression of gastric cancer. However, the mechanisms that regulate this activation in gastric tumors remain elusive. CACUL1 has been cloned and identified as a novel gene that is expressed in many types of cancer and is involved in cell cycle regulation and tumor growth. The current study aimed to examine the expression of CACUL1 in gastric cancer samples and analyze its correlation with H. pylori infection. We found that CACUL1 was highly expressed in gastric cancer tissues and negatively correlated with gastric cancer differentiation and TNM stage. In addition, CACUL1 expression was high in H. pylori-infected tissues compared with H. pylori non-infected tissue. We found that H. pylori could up-regulate CACUL1 expression through activating protein 1. The up-regulation of CACUL1 expression could promote matrix metalloproteinase 9 and Slug expression to increase invasion and metastasis of tumor cells. These results suggested that H. pylori-triggered CACUL1 production occurred in an activating protein 1-dependent manner and regulated matrix metalloproteinase 9 and Slug expression to affect the invasion and metastasis of tumor cells. Therefore, CACUL1 is a potential therapeutic target for the treatment of aggressive gastric cancer.

Biological activation of heteropoly complex of molybdotungstosilicate containing lanthanum K10H 3La(SiMo6W5O39)2x26H2O: spectroscopic approach and microcalorimetry.

In this paper, the biological activation of heteropoly complex of molybdotungstosilicate containing lanthanum K(10)H(3)La(SiMo(6)W(5)O(39))(2)x26H(2)O (LaW(5)) was investigated by spectroscopic approach and microcalorimetry under the human physiological conditions. Fluorescence spectroscopy in combination with UV-Vis absorption spectroscopy was employed to investigate the binding of LaW(5) to bovine serum albumin (BSA). In the mechanism discussion, it was proved that the fluorescence quenching of BSA by LaW(5) is a result of the formation of LaW(5)-BSA complex. Binding parameters were determined using the Stern-Volmer equation. The results of thermodynamic parameters G, H, S at different temperatures indicate that van der Waals interactions and hydrogen bonds play a major role for LaW(5)-BSA association. The distance r between donor (BSA) and acceptor (LaW(5)) was obtained according to fluorescence resonance energy transfer. Furthermore, the calorimetric method was used to monitor the biological activity of LaW(5) in Escherichia coli.

A series of novel rare Earth molybdotungstosilicate heteropolyoxometalates binding to bovine serum albumin: spectroscopic approach.

Heteropolyoxometalate complexes have been widely applied in many fields. In this paper, the interaction between a series of novel rare earth molybdotungstosilicate heteropolyoxometalates, K(10)H(3)[Ln(SiMo(6)W(5)O(39))(2)].xH(2)O (abbr. LnW(5), Ln = Pr (x = 30), Gd (x = 29), Dy (x = 28), and Yb (x = 31)), and bovine serum albumin (BSA) was investigated by spectroscopic approach under the physiological conditions. In the mechanism discussion, it was proved that the fluorescence quenching of BSA by LnW(5) is a result of the formation of LnW(5)-BSA complex. Fluorescence quenching constants were determined using the Stern-Volmer equation to provide a measure of the binding affinity between LnW(5) and BSA. The binding affinity ranked in the order GdW(5) > DyW(5) > PrW(5) > YbW(5). The results of thermodynamic parameters DeltaG, DeltaH, and DeltaS at different temperatures indicate that van der Waals interactions and hydrogen bonds play a major role for LnW(5)-BSA association. Furthermore, the distance r between donor (BSA) and acceptor (LnW(5)) was obtained according to fluorescence resonance energy transfer.