Biology 2581B Study Guide - Quiz Guide: Nuclear Magnetic Resonance, Protein Data Bank, Transmission Electron Microscopy
3 Jun 2020
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Document Summary
X-rays enter the crystallised molecule that diffracts the ray on the x-ray detector, then the diffraction pattern is computed and refined manually to get an electron density map and thus a protein structure model. Proteins must be crystallisable and static structure obtained in solid state. Typically 0. 9-3a resolution (c-h bond length is 1. 1a and c-c bonds can be observed) Advantages : can solve very large structures as well as small ones can soak (immerse in liquid for a certain time to make it wet) different ligands into crystals to obtain ligand-bound structures. Disadvantages : crystallisation process can be slow crystallisation can deform structure through contacts between proteins. Unstable or mobile regions cannot be observed. H atoms positions are inferred only as not directly detected. Nuclear spins have high and low energy states in a permanent magnetic field. Rf coil at a frequency matched to energy gap induces spin alignment to high energy.
