Effects of precipitation process on the biophysical properties of highly concentrated proteins

Quantitative analysis of therapeutic proteins in biological fluids: recent advancement in analytical techniques

Pharmaceutical application of therapeutic proteins has been continuously expanded for the treatment of various diseases. Efficient and reliable bioanalytical methods are essential to expedite the identification and successful clinical development of therapeutic proteins. In particular, selective quantitative assays in a high-throughput format are critical for the pharmacokinetic and pharmacodynamic evaluation of protein drugs and to meet the regulatory requirements for new drug approval. However, the inherent complexity of proteins and many interfering substances presented in biological matrices have a great impact on the specificity, sensitivity, accuracy, and robustness of analytical assays, thereby hindering the quantification of proteins. To overcome these issues, various protein assays and sample preparation methods are currently available in a medium- or high-throughput format. While there is no standard or universal approach suitable for all circumstances, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay often becomes a method of choice for the identification and quantitative analysis of therapeutic proteins in complex biological samples, owing to its high sensitivity, specificity, and throughput. Accordingly, its application as an essential analytical tool is continuously expanded in pharmaceutical R&D processes. Proper sample preparation is also important since clean samples can minimize the interference from co-existing substances and improve the specificity and sensitivity of LC-MS/MS assays. A combination of different methods can be utilized to improve bioanalytical performance and ensure more accurate quantification. This review provides an overview of various protein assays and sample preparation methods, with particular emphasis on quantitative protein analysis by LC-MS/MS.

Design of millidevices to expedite apparent solubility measurements

A fast, automated and accurate millidevice for determination of the apparent solubility of proteins and impurities and different industrially relevant precipitating agents.

Utilization of tofu processing wastewater as a source of the bioactive peptide lunasin

The goal of our study was to design a simple and feasible method to obtain lunasin, a naturally-occurring bioactive peptide, from tofu whey wastewater. A combination of alcoholic precipitation of high-molecular weight proteins from the whey, isoelectric precipitation of lunasin enriched material, and purification via gel filtration chromatography was selected as the best approach using tofu whey prepared at the laboratory scale. This process was applied to tofu whey produced by a local tofu factory and 773 mg of 80% purity lunasin was obtained per kg of dry tofu whey. Significant reduction of nitric oxide, and pro-inflammatory cytokines TNF-α and IL-6 over lipopolysaccharide activated murine macrophages demonstrate its biological activity. Our three-step process is not only simpler and faster than the previously reported methods to obtain lunasin but provides a sustainable approach for the valorization of a waste product, promoting the better utilization of soybean nutrients and active compounds.