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[en] Dielectric measurements of serum albumin and myoglobin in solutions of varying conductivities were performed. The results presented confirm that also for protein solutions, the Maxwell predictions of a threshold frequency in conducting materials holds. The threshold frequency of a serum albumin solution was experimentally determined. Attention should be recalled that, if the dielectric spectra of proteins solutions want to be measured, three distinct frequency regions are to be observed: a low frequency region, where the sample behaves like a conductor; an intermediate region centered around the threshold frequency, where the free charges partially screen the fixed ones; and a high frequency region where the sample behaves like a good dielectric. (author). 8 refs, 5 figs
[en] Human immunoglobulin (IgG), bovine fibrinogen and bovine serum albumin were irradiated at room temperature with short pulses (50 ns to 2 μs) of 16 MeV electrons in 0.2 M NaClO4 solution containing phosphate buffer (pH 7.5). In the presence of N2O the intensity of light (LSI) scattered by the protein solutions increased after the pulse indicating aggregation. The latter process originates from the attack of protein molecules by OH radicals (aggregation is impeded by t-butanol and augmented by N2O). Upon plotting the relative increase of LSI vs. log time (after the pulse) sigmoidally shaped curves were obtained. From these findings and results of optical absorption measurements the following is inferred: Aggregation occurs as a consequence of chemical alterations of the protein molecules induced by the attack by OH radicals. The transient species formed during and a few μs after the pulse are reacting within a period of several ms. At the end of this period the formation of aggregates starts. It is concluded that the primary radiation chemical process consists (among others) in the generation of nucleation sites. The latter subsequently initiate aggregation processes. (orig.)
[en] Measurement of urinary albumin has been used to indicate the degree of renal impairment in patients with clinically diagnosed Diabetes Mellitus and essential Hypertension. Conventional tests for detecting protein in urine lack the sensitivity to delineate this condition and very often yield negative results even when the albumin excretion rate is 10 or 20 times normal. The need to develop highly sensitive assay to screen patients with subclinically elevated albumin excretion is therefore apparent. We developed and validated a rapid, sensitive and precise radioimmunoassay to measure urinary albumin ranging from 5 - 200 mg/l. The technique is PEG- double antibody liquid phase. The iodinated tracer and standard human serum albumin (HSA) were prepared to be used with selected antibody. The method for labelling HSA and the optimization procedure were included. The sensitivity of the assay was found to be 0.22 mg/l with the precision at 10 % CV cover the range of clinical interest(0-100 mg/l)
[en] In the present investigation the interaction of a biologically active photodynamic therapeutic agent Toluidine blue O (TBO) with Serum albumins viz Human serum albumin (HSA) and Bovine serum albumin (BSA) was studied using absorption, emission, circular dichroism spectroscopy and molecular docking experiments. The emission titration experiments between HSA/BSA and TBO revealed the existence of strong interactions between TBO and the proteins. The site competitive experiment of HSA and BSA showed that the primary binding site of TBO is located in site I of HSA/BSA involving hydrophobic, hydrogen bonding and electrostatic interaction. To ascertain the results of site competitive experiments, molecular docking was utilized to characterize the binding models of TBO–HSA/BSA complexes. From the molecular docking studies, free energy calculations were undertaken to examine the energy contributions and the role of various amino acid residues of HSA/BSA in TBO binding. The existence of Forster Resonance Energy Transfer (FRET) between the ligand and the protein was utilized to calculate the donor–acceptor distance of TBO and protein. The TBO induced conformational changes of HSA/BSA was established using synchronous emission, three dimensional emission and circular dichroism studies. - Highlights: • Site selective binding interaction of TBO with HSA and BSA were investigated. • TBO quenches the intrinsic fluorescence of HSA/BSA by static quenching process. • Computational studies of TBO with HSA/BSA substantiate the experimental findings. • 3D and CD spectral studies of TBO–HSA/BSA revealed structural changes in protein. • The distance (r) between TBO and HSA/BSA were estimated from FRET theory
[en] A test antigen for detecting antibodies to a diisocyanate comprises the reaction product of a protein and a monoisocyanate derived from the same radical as the diisocyanate. The diisocyanates most usually encountered and therefore calling for antibody detection are those of toluene, hexamethylene, methylene, isophorone and naphthylene. The preferred protein is human serum albumin. (author)
[en] Highlights: • Cisplatin-induced nephrotoxicity showed a circadian rhythm. • Cisplatin altered the clock genes expression in a tissue- and gene-specific manner. • Dbp was consistently suppressed in peripheral tissues after cisplatin treatment. Cisplatin is a platinum-based chemotherapy drug that is widely used to treat various types of malignancies. Although the involvement of circadian clock in cisplatin metabolism and excretion has been reported, the effect of cisplatin on circadian rhythm remains unclear. In the present study, we investigated the effects of cisplatin on clock genes expression in mouse peripheral tissues. Cisplatin induced severe nephrotoxicity, as revealed by the significant increase of blood urea nitrogen and serum creatinine levels. Moreover, cisplatin circadian time-dependently induced p21 expression in the liver, heart and kidney, with the highest increase during the dark phase. In addition, cisplatin altered the clock genes expression in the liver, heart and kidney in a tissue- and gene-specific manner. Interesting, the expression of D site of the albumin promoter binding protein (Dbp), a gene involved in detoxification and drug metabolism, was consistently suppressed in the liver, heart and kidney after cisplatin treatment, implying a role of DBP in the toxicity of cisplatin.
[en] It is always a challenge to achieve the selective recognition between human serum albumin (HSA) and bovine serum albumin (BSA) because of their highly homologous primary structure. In this work, we reported two red-NIR fluorescence probes, BI-FPI and NTPS-FPI, for HSA and BSA differential recognition. BI-FPI showed remarkable emission enhancement toward HSA over BSA, while NTPS-FPI exhibited the opposite selectivity toward BSA. The obvious different interaction for probes with HSA and BSA were demonstrated by site specific competitive binding experiments and molecular docking studies. BI-FPI located within site I of HSA, which mainly depended on the hydrophobic residues and π-π interaction. While NTPS-FPI docked into the interface between subdomains II and IIIA of BSA, and the strong hydrogen bond interaction was the main contributor for the binding. Furthermore, the good calibration graphs of BI-FPI to HSA enabled us to develop the attractive multiple functional probe for qualitatively and quantitatively detecting HSA, and the detection limit (0.01 μM, 0.66 mg/L) met the requirements of traditional HSA assay in serum or in urine (30 mg/L).