紫背天葵红色素与牛血清白蛋白的作用研究

以最优化条件从紫背天葵中提取出天然红色素,采用可见光谱研究了其与牛血清白蛋白（BSA）的相互作用。     

BSA载体蛋白抗体的去除

为了去除抗血清中BSA载体蛋白产生的抗体,一根对BSA载体蛋白抗体高度特异性的亲和柱被构建。结果表明：所构建的亲和柱对BSA载体蛋白抗体具高度特异性和亲和力,能有效地去除BSA载体蛋白产生的抗体。     

Molecular Mobility and Oxygen Permeability in Amorphous Bovine Serum Albumin Films

We have used phosphorescence from the xanthene probe erythrosin B to characterize the molecular mobility and oxygen permeability as a function of temperature in amorphous solid bovine serum albumin (BSA) films. Analysis of the emission spectrum using a lognormal fitting function provided information on how temperature modulates the emission peak frequency and bandwidth (full width at half maximum). The peak frequency decreased gradually at low and more steeply at high temperature, whereas the bandwidth increased gradually at low and more steeply at high temperature, both changes indicating a softening of the protein matrix at ∼60°C. Phosphorescence intensity decay transients were well fit using a stretched exponential decay function at all temperatures. Lifetimes decreased gradually at low and more steeply at high temperature; Arrhenius analysis of the rate constant for nonradiative collisional quenching indicated an increase in quenching indicative of matrix softening at ∼70°C. The oxygen quenching rate was calculated from a comparison of emission lifetimes in the presence and absence of oxygen. This rate varied linearly with the collisional quenching rate over nearly three orders of magnitude, suggesting that the more global motions that control oxygen translational diffusion are modulated by more local motions that influence collisional quenching of erythrosin. The emission spectrum shifted to higher energy as a function of time following excitation, whereas the phosphorescence lifetime decreased with increasing emission wavelength; both behaviors provided strong evidence for distinct sites within the protein matrix varying in molecular mobility. These results enrich our molecular understanding of the intrinsic mobility of proteins within the amorphous solid phase, provide evidence for a dynamic transition within solid BSA, and provide insight into the molecular mechanisms controlling oxygen diffusion.     

Interactions of Chromium (III) and Chromium (VI) with Bovine Serum Albumin Studied by UV Spectroscopy,Circular Dichroism,and Fluorimetry

In the present work, the interactions of bovine serum albumin (BSA) with chromium (III) chloride, potassium dichromate, and chromate were studied by fluorescence, circular dichroism, and UV–vis absorbance spectroscopy. Fluorescence quenching of BSA by chromium (III) was found to be a dynamic process in the beginning, turning static at later stages. Spectroscopic data show that both dichromate and chromate bind in similar electrostatic fashion to BSA and does not follow the fluorescence quenching observation for chromium (III).     

Flow cytometry: a promising technique for the study of silicone oil-induced particulate formation in protein formulations

Subvisible particles in formulations intended for parenteral administration are of concern in the biopharmaceutical industry. However, monitoring and control of subvisible particulates can be complicated by formulation components, such as the silicone oil used for the lubrication of prefilled syringes, and it is difficult to differentiate microdroplets of silicone oil from particles formed by aggregated protein. In this study, we demonstrate the ability of flow cytometry to resolve mixtures comprising subvisible bovine serum albumin (BSA) aggregate particles and silicone oil emulsion droplets with adsorbed BSA. Flow cytometry was also used to investigate the effects of silicone oil emulsions on the stability of BSA, lysozyme, abatacept, and trastuzumab formulations containing surfactant, sodium chloride, or sucrose. To aid in particle characterization, the fluorescence detection capabilities of flow cytometry were exploited by staining silicone oil with BODIPY 493/503 and model proteins with Alexa Fluor 647. Flow cytometric analyses revealed that silicone oil emulsions induced the loss of soluble protein via protein adsorption onto the silicone oil droplet surface. The addition of surfactant prevented protein from adsorbing onto the surface of silicone oil droplets. There was minimal formation of homogeneous protein aggregates due to exposure to silicone oil droplets, although oil droplets with surface-adsorbed trastuzumab exhibited flocculation. The results of this study demonstrate the utility of flow cytometry as an analytical tool for monitoring the effects of subvisible silicone oil droplets on the stability of protein formulations.