Antibody Fragments and Their Purification by Protein L Affinity Chromatography

Antibodies and related proteins comprise one of the largest and fastest-growing classes of protein pharmaceuticals. A majority of such molecules are monoclonal antibodies; however, many new entities are antibody fragments. Due to their structural, physiological, and pharmacological properties, antibody fragments offer new biopharmaceutical opportunities. In the case of recombinant full-length antibodies with suitable Fc regions, two or three column purification processes centered around Protein A affinity chromatography have proven to be fast, efficient, robust, cost-effective, and scalable. Most antibody fragments lack Fc and suitable affinity for Protein A. Adapting proven antibody purification processes to antibody fragments demands different affinity chromatography. Such technology must offer the unit operation advantages noted above, and be suitable for most of the many different types of antibody fragments. Protein L affinity chromatography appears to fulfill these criteria—suggesting its consideration as a key unit operation in antibody fragment processing

Reactivity Ratios of Comonomers from a Single MALDI–ToF–MS Measurement at One Feed Composition

The reactivity ratios in a copolymerization are needed to predict the microstructure (random, gradient, block or alternating) of the produced copolymer. This microstructure reflects on the physical properties of the polymeric material. Conventional ways to determine these reactivity ratios demand in most cases tedious laboratory work and several experiments at different monomer feed compositions. Here, a novel method is described to derive these ratios from a single MALDI-ToF-MS spectrum obtained at one feed composition by employing either a Monte Carlo approach to numerically simulate a first order Markov chain or the analytical form of the first order Markov chain. A single MALDI-ToF-MS spectrum proved to give very good estimates of the reactivity ratios of comonomers from copolymer's synthesized by free radical polymerization, ring-opening polymerization of lactones and lactides, or ring-opening copolymerization of anhydrides plus epoxides