Refinement

Question 1

I/sigma(I)

Answer 1

Describes the determined reflection intensities compared to average

Question 2

Rigid Body Refinement

Answer 2

Treats parts of the protein as a rigid body.
Can fit to low resolution data with high radius of convergence.

Question 3

A siagmaA-weighted map is good for? And what is m and D?

Answer 3

Are the least biased, for our model.
m - figure of merit, related to phase error
D - Luzzati D-factor compensates for missing or incorrect part of model

Question 4

Rfree

Answer 4

= sum(Fobs-Fcalc)/sum(Fobs)
Fobs comes from test dataset that was not used in refinement.

Question 5

Refinement aims to?

Answer 5

Fix local errors.
Aims to optimize fit:
*calculated and observed structure factor amplitudes
*model and ideal stereochemical parameters

Question 6

Validation

Answer 6

Discloses large errors –> remodelling