Single electron transfer events and dynamical heterogeneity in the small protein azurin from Pseudomonas aeruginosa.

Monitoring the fluorescence of single-dye-labeled azurin molecules, we observed the reaction of azurin with hexacyanoferrate under controlled redox potential yielding data on the timing of individual (forward and backward) electron transfer (ET) events. Change-point analysis of the time traces demonstrates significant fluctuations of ET rates and of mid-point potential E 0. These fluctuations are a signature of dynamical heterogeneity, here observed on a 14 kDa protein, the smallest to date. By correlating changes in forward and backward reaction rates we found that 6% of the observed change events could be explained by a change in midpoint potential, while for 25% a change of the donor-acceptor coupling could explain the data. The remaining 69% are driven by variations in complex association constants or structural changes that cause forward and back ET rates to vary independently. Thus, the observed spread in individual ET rates could be related in a unique way to variations in molecular parameters. The relevance for the understanding of metabolic processes is briefly discussed.

MYC associated zinc finger protein promotes the invasion and metastasis of hepatocellular carcinoma by inducing epithelial mesenchymal transition.

MYC associated zinc finger protein (MAZ) plays a key role in regulation of gene expression and tumor development. Studies have shown that deregulated expression of MAZ is closely related to the progression of tumors such as glioblastoma, breast cancer, prostate cancer and liposarcoma. However, the role of MAZ in hepatocellular carcinoma (HCC) has not been fully elucidated. Here, we found that expression of MAZ was increased in HCC and correlated to the distant metastasis of HCC. Moreover, we found that MAZ had a relationship with zinc finger E-box binding homeobox 1 and 2 (ZEB1 and ZEB2), two important mesenchymal markers in epithelial-mesenchymal transition (EMT) that were over-expressed in HCC. After knocking-down MAZ expression in HCC cell lines using RNA interruption, HCC cell proliferation, tumorigenesis, invasion and migration were significantly inhibited. In addition, we found that expression of other EMT markers was also changed besides ZEB1 and ZEB2 by decreasing MAZ expression, both detected in vivo and in vitro assays. Therefore, we conclude that MAZ can promote the invasion and metastasis of HCC by inducing EMT.

Simultaneous laser-induced fluorescence, coaxial thermal lens spectroscopy and retro-reflected beam interference detection for capillary electrophoresis.

A simultaneous laser-induced fluorescence (LIF), coaxial thermal lens spectroscopy (TLS) and retro-reflected beam interference (RBI) detection for capillary electrophoresis (CE), has been described. In its optical scheme, a diode-pump solid-state (DPSS) laser was employed as the pump laser in both LIF detection and coaxial TLS detection, and a He-Ne laser was utilized as the probe laser in coaxial TLS detection and RBI detection. In addition, RBI signals with and without thermal lens had been theoretically compared to ensure the reliability of the RBI signal. Moreover, the focus length of the key lens has been optimized to improve the performance of the proposed detection. The last but not least, several determinations were taken to evaluate its limit of detection, linear range as well as relative standard deviation, all of which indicate no worse results compared with former reports. LIF and coaxial TLS detection owned high sensitivity, and RBI detection indicated versatile property, based on which the reported detection achieved a sensitive and universal detection for CE.

A separation-free method for simultaneous determination of and sunset yellow in different abundance by integrating RBI and detectors.

A novel method for simultaneous determination of sucrose and sunset yellow in retail soft drink without separation by combination of retro-reflected beam interference-based refractive index (RBI) and thermal lens (TL) detections was developed. The method proposed here successfully realized individual measurements of sucrose and sunset yellow in one single sample, while their concentrations were thousands of times different in the sample. Under optimized conditions, a separation-free process was carried out so that sucrose and sunset yellow were quantified at the same time. Limits of detection (LODs) of sucrose and sunset yellow were 0. 21 mg ml-1 and 0.23 µg ml-1 and the relative standard deviation (RSDs) were 3.9% and 3.07%. The developed method was successfully applied for the simultaneous analysis of sucrose and sunset yellow in retail soft drink. The soft drink containing 123.6 ± 2.6 mg ml-1 sucrose and 46.6 ± 1.8 µg ml-1 sunset yellow have been simultaneously measured without any separation procedure.

Simultaneous LIF and retro-reflected beam interference detection for CE.

This Short Communication describes a novel optical detection method for CE, based on the combination of LIF detection and retro-reflected beam interference detection. By the use of a side-illuminated laser beam, an on-column multifunctional detection for CE has been developed, and some key elements in the scheme have been optimized. In addition, two miscellaneous samples including fluorescent dyes, carbohydrates and amino acids have been determined to evaluate its performance. Without any additional pretreatment, sufficient LOD and linear ranges have been achieved for most analytes. Its performance in retro-reflected beam interference detection is better than those mentioned in a former report, and its fluorescent sensitivity is comparable with the achievable sensitivity by conventional LIF systems, all of which together combine high sensitivity and universal analysis to a certain extent.

Simultaneous coaxial thermal lens spectroscopy and retro-reflected beam interference detection for capillary electrophoresis.

A novel optical scheme, which accomplished simultaneous coaxial thermal lens spectroscopy and retro-reflected beam interference detection for capillary electrophoresis, has been described. By a special design, an adjustable pump laser waist relative to the probe laser waist was implemented, while some key elements for both detection modes were optimized. In either detection modes, certain preponderance compared with former reports was indicated. With both coaxial thermal lens spectroscopy and retro-reflected beam interference detection, the reported detection scheme combined high sensitivity and universal property for capillary electrophoresis detection.