The use of self-interaction chromatography in stable formulation and crystallization of proteins.

This paper reviews the basic principles of the recently developed self-interaction chromatography (SIC) technique with regard to protein solution stability and protein crystallization. It gives experimental protocols for both normal-scale and micro-scale SIC experiments and reviews recent developments and current applications of this novel technique in the biopharmaceutical area. This paper aims to be a benchmark in the further proliferation of this highly effective and fast technology for the rational design of stable aqueous formulations of therapeutic proteins and the determination of solution conditions favoring protein crystallization.

Protein self-interaction chromatography on a microchip.

This paper presents the development of a novel miniaturized experimental procedure for the measurement of protein-protein interactions through Self-Interaction Chromatography (SIC) on a microchip, without the use of chromatographic resins. SIC was recently demonstrated to be a relatively easy method to obtain quantitative thermodynamic information about protein-protein interactions, like the osmotic second virial coefficient B(22), which relates to protein phase behavior including protein crystallization. This successful miniaturization to microchip level of a measurement device for protein self-interaction data is a first key step to a complete microfluidic screening platform for the rational design of protein crystallizations, using substantially less expensive protein and experimentation time.

Lipase-catalyzed ethanolysis of milk fat with a focus on short-chain fatty acid selectivity.

Mixtures of fatty acid ethyl esters were produced by lipase-catalyzed ethanolysis of milk fat triglycerides. Three commercial immobilized lipases (Lipozyme TL, Lipozyme RM, and Novozym 435) were tested in different reaction conditions with the aim of maximizing the conversion of the short-chain fatty acid fraction of milk fat to flavor ethyl esters. The influence of the reactants molar ratio was investigated, as well as three different reaction media, that is, hexane, CO(2)-expanded liquid (GXL), and the solvent-free mixture. Novozym 435 showed the highest activity in all conditions. This lipase also exhibited selectivity for short-chain fatty acids, which, at short reaction times, resulted in a product mixture richer in short-chain fatty acids than the original milk fat. The highest selectivities were obtained in hexane and in CO(2)-expanded liquid fat, at low ethanol to fat ratios. Using dense CO(2) as the reaction cosolvent is attractive because it results in the largest short-chain fatty acid enrichment in the product mixture, while leaving no residues in the product.

Reducing CO2 emissions and energy consumption of heat-integrated distillation systems.

Distillation systems are energy and power intensive processes and contribute significantly to the greenhouse gases emissions (e.g. carbon dioxide). Reducing CO2 emissions is an absolute necessity and expensive challenge to the chemical process industries in orderto meetthe environmental targets as agreed in the Kyoto Protocol. A simple model for the calculation of CO2 emissions from heat-integrated distillation systems is introduced, considering typical process industry utility devices such as boilers, furnaces, and turbines. Furnaces and turbines consume large quantities of fuels to provide electricity and process heats. As a result, they produce considerable amounts of CO2 gas to the atmosphere. Boilers are necessary to supply steam for heating purposes; besides, they are also significant emissions contributors. The model is used in an optimization-based approach to optimize the process conditions of an existing crude oil atmospheric tower in order to reduce its CO2 emissions and energy demands. It is also applied to generate design options to reduce the emissions from a novel internally heat-integrated distillation column (HIDiC). A gas turbine can be integrated with these distillation systems for larger emissions reduction and further energy savings. Results show that existing crude oil installations can save up to 21% in energy and 22% in emissions, when the process conditions are optimized. Additionally, by integrating a gas turbine, the total emissions can be reduced further by 48%. Internal heat-integrated columns can be a good alternative to conventional heat pump and other energy intensive close boiling mixtures separations. Energy savings can reach up to 100% with respect to reboiler heat requirements. Emissions of these configurations are cut down by up to 83%, compared to conventional units, and by 36%, with respect to heat pump alternatives. Importantly, cost savings and more profit are gained in parallel to emissions minimization.