Effect of salt modulators on the elution behavior of insulin and the separation of product-related impurities in reversed-phase chromatography.

In this work, the effect of the salt modulators potassium chloride, ammonium chloride, ammonium sulfate, and potassium sulfate on the elution behavior of insulin in reversed-phase chromatography with ethanol as the organic modifier was investigated. Without the addition of salt modulators, insulin shows the formation of multiple peaks under non-linear loading conditions, presumably due to an aggregate formation equilibrium. Flow rate and temperature did not influence the appearance of multiple peaks.

Mechanistic modeling of cation exchange chromatography scale-up considering packing inhomogeneities.

In process development and characterization, the scale-up of chromatographic steps is a crucial part and brings a number of challenges. Usually, scale-down models are used to represent the process step, and constant column properties are assumed. The scaling is then typically based on the concept of linear scale-up.

Mechanistic modeling and simulation of a complex low and high loading elution behavior of a polypeptide in cation exchange chromatography.

The mechanistic modeling of preparative liquid chromatography is still a challenging task. Nonideal thermodynamic conditions may require activity coefficients for the mechanistic description of preparative chromatography. In this work, a chromatographic cation exchange step with a polypeptide having a complex elution behavior in low and high loading situations is modeled.

Model-based monitoring of industrial reversed phase chromatography to predict insulin variants.

Downstream processing in the manufacturing biopharmaceutical industry is a multistep process separating the desired product from process- and product-related impurities. However, removing product-related impurities, such as product variants, without compromising the product yield or prolonging the process time due to extensive quality control analytics, remains a major challenge. Here, we show how mechanistic model-based monitoring, based on analytical quality control data, can predict product variants by modeling their chromatographic separation during product polishing with reversed phase chromatography.

Structural and redox properties of the small laccase Ssl1 from Streptomyces sviceus.

Unlabelled: Laccases (EC 1.10.3.

Enhancement of copper content and specific activity of CotA laccase from Bacillus licheniformis by coexpression with CopZ copper chaperone in E. coli.

Copper depletion of bacterial laccases obtained by heterologous expression in Escherichia coli is a common problem in production of these versatile biocatalysts. We demonstrate that coexpression of small soluble copper chaperones can mitigate this problem. The laccase CotA and the copper chaperone CopZ both from Bacillus licheniformis were used as model system.

Characterization of the alkaline laccase Ssl1 from Streptomyces sviceus with unusual properties discovered by genome mining.

Fungal laccases are well investigated enzymes with high potential in diverse applications like bleaching of waste waters and textiles, cellulose delignification, and organic synthesis. However, they are limited to acidic reaction conditions and require eukaryotic expression systems. This raises a demand for novel laccases without these constraints.