Quiz Questions On The Properties Of A Protein At Dna Level

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BIOT643 Fall 2015- Quiz-3 Answers (60 points)
- Deepa Thamodaran

1. a) SDS-Polyacrylamide Gel electrophoresis
2. b) Change the properties of a protein at DNA level
3. c) Nuclear magnetic resonance
4. b) Northern blot hybridization
5. Far Western Blot analysis and Protein arrays
Far Western Blot analysis:

Far Western Blot analysis is the technique mostly resembles Western Blot analysis, but differs in way that proteins are separated on a blot. Biotinylated non-antibody proteins are used for immobilizing the protein of interest, which are then overlaid with an antibody with streptavidin. Many proteins show considerable affinity for biotin which is a co-factor in many eukaryotic biological processes.
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Fluorescent signals are emitted when there is reaction between the immobilized protein and the probe, which are captured by the laser scanners. Thus they are used in protein expression profiling, studying protein-protein interactions, enzyme-substrate interactions, protein-ligand interaction and differentially expressed proteins screening on a large scale.
6. X-Ray Crystallography and NMR are two common methods used to study protein structures. X-Ray Crystallography NMR
Principle Protein molecules are crystallized and exposed to X-rays. A crystal arranges a large number of molecules in the same orientation, so the scattered waves add up in phase and raise the signal. Protein molecules are made soluble in buffered liquid and isotopically labeled. Therefore, allows thermodynamics, studies of the kinetics aspects of structures and interactions with other components.
Physical state Frozen solid state Liquid state in buffered solution
Time Longer time in screening and optimization but short time for processing data. Short time for preparation but long time for data analysis.
Size Any size of macromolecule Small polypeptide (< 50 kDa)
Advantages Well-diffracting crystals achieve high atomic resolution Soluble state favors mere closer to protein in folding state which is like real functional environments.
Disadvantages Crystallization may change the conformation of proteins due to packing interactions therefore more
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