The instrument, dubbed the Calypso, enables the walk-away quantitative and non-destructive characterisation of protein-protein interactions in native solution without the need to label or immobilise the samples. This allows researchers to analyse the impact of small molecules on protein-protein interactions, determine the best antibody purification methods and optimise buffer conditions for protein crystallography. In addition, the system can be used to determine the effects of ionic strength, pH or excipients on biological aggregation enabling the optimisation of vaccine and biological drug formulations for injection or infusion. The system uses a technique known as composition-gradient multi-angle light scattering (CG-MALS) to directly measure the molecular mass and radius of large molecules in solution. According to Dr Dan Some, principal scientist at Wyatt Technology, the technique is very sensitive and is useful from the start of the drug discovery process to formulation development. "The system is useful for all of the steps involved in drug discovery, protein formulation, purification and QC," said Dr Some. The CG-MALS technique only needs small amounts of sample to conduct experiments, which is particularly important considering how expensive some proteins can be to make. The sample quantities needed to measure equilibrium protein constants ranges from tens of micrograms to a few milligrams depending on the strength of the protein interactions; with the measurement of stronger binding interactions needing less sample. More advanced configurations of the Calypso enable the sample requirements to be reduced as much as tenfold. Kinetics experiments can also be conducted with the amount of protein needed ranging from a few micrograms to hundreds of micrograms. The Calypso system interfaces with Wyatt's light scattering detectors the Dawn-Heleos and miniDawn-Treos and a concentration detector such as Wyatt's Optilab rEX to automate interaction measurements that were prohibitively labour intensive. "It isn't really feasible to measure such sensitive protein interactions manually using light scattering techniques as many different concentrations and verifications would need to be prepared before the experiments could be conducted," said Dr Some. "The Calypso automates all these steps, so after you've prepared the stock and buffer solutions and connected them up to the system; it takes a minute or two to programme the system and then you can just walk away and let the system collect the data." Various application notes on the use of the technology are available on Wyatt Technologies' website detailing the use of the system for generating standard and online Zimm plots used to calculate the virial coefficient that is often used as a measure of protein purity, as well as reversible self association and the characterisation of protein-protein interactions. According to Dr Some, there are more application notes on the way, including the use of small molecules to inhibit protein-protein association and aggregation. "This system would be ideal for studying the ability of potential Alzheimer's therapies to inhibit the aggregation of the amyloid proteins believed to be involved in the progression of the disease," said Dr Some. Protein aggregation can also be a problem in biologic drug formulation where stability is often key to the activity of these drugs. Checking that a product is stable over time and is not aggregated when leaving the manufacturing plant will play an increasingly important role in QC laboratories as more and more biological drugs are released. While the Calypso's software is not yet compliant with the US Food and Drug Administrations FDA 21 CFR(11) rules the data may be collected and analysed using Wyatt's Astra software that does support the regulated environment.