exploring proteins lecture 3 Flashcards
nuclear magnetic resonance
has 2 states
spin e-
excited state and lower state
what does nuclear magnetic resonance tell us
tells us the environment of the nucleus
what does nmr use
correlation between 2 protons`
if 2 protons are close together they show a
correlation peak
which shows that they exchange energy between the 2
triangulation is used to
find the atoms which are close to each other
conversion of distance leads to family of structures
which are structurally similar
so what is dynamic
the side changes
which are flexible
using N15 instead of 14 what happens
for every aa 1 peak for N
chemical shift changes
can study ligand binding where it binds
3 EM variants
negative stained EM
cryo EM
em diffraction
negative stained EM strengths and limitations
strength : small amount of sample
limitation : resolution at 20A
cryo em strengths and limitations
strength: small amount of sample
no staining necessary
limitations: resolution depends on averaging technique -10A
em diffraction strenghts and limitations
requires only 2d crytals
resolution 3-4A
x-ray and neutron scattering strengths
strengths: large range of macromolecules
measurements in sol
approx mg of pure protein required
x-ray and neutron scattering limitations
resolution approx 20A
only shape info
best in combination with other techniques
neutron scattering requires more material and best suited with some level of deuteration
x-ray crystallography strengths
high resolution less then 1A
enormous info content
x-ray crystallography limitations
need to form crystals
may prove impossible
crystals may influence dynamic environment/weak interactions
