Summary
Highlights
Crystallization involves creating a supersaturated protein solution and dehydrating it in a controlled manner, similar to how sodium acetate rapidly crystallizes. Due to the difficulty of crystallizing some proteins, small volumes are loaded into trays with various additives, and robots assist with pipetting.
The video introduces the three-dimensional structure of lysozyme, an enzyme in tears, saliva, and mucus that fights bacteria. Understanding its 3D structure helps to comprehend its mechanism of action. Due to the molecule's tiny size, too small for light microscopes, X-rays are used.
Protein crystals contain millions of protein molecules arranged in an ordered grid. Firing X-rays at these crystals and measuring their scattering allows scientists to determine the molecular structure of crystallized samples. This method, X-ray crystallography, has revealed structures from DNA's double helix to proteins, vitamins, and drugs.
Before crystallization, proteins must be produced and purified in significant quantities. This involves genetically modifying E. coli bacteria to act as protein 'factories'. After incubation, the bacteria are opened, the protein is extracted, and then purified, ready for crystallization.
An individual protein molecule, despite its complex folded structure, will scatter X-rays randomly, yielding no information. However, when protein molecules are aligned in an ordered array within a crystal, X-rays scatter in a way that provides enough signal to determine the protein's three-dimensional structure.
The trays are then stored in a 'Crystal Hotel' for several weeks at 4°C, where cameras monitor for crystal formation. Once crystals are grown, they are taken for X-ray analysis, often requiring powerful X-ray sources at specialized facilities like the Diamond Light Source, the UK's most sophisticated scientific facility.