What is it about X−rays that makes them so useful in crystallography? It is their very short wavelengths. X−rays are between 10 nm and 0.01 nm in length,

What is it about X−rays that makes them so useful in crystallography? It is their very short wavelengths. X−rays are between 10 nm and 0.01 nm in length,

in a heart valve —Frank et al 1994

Source: Biosites, David S. Goodsell, Scripps

The Basement Membrane is a layer of fibers found under the epidermis, also around the capillaries, in kidneys, etc. Goodsell’s painting of it is based microscopic views and on PDB structures like the one below

Introduction to THE PROTEIN DATA BANK

& What X-ray Crystallography Can Show Us About the Structures of Important Proteins

Basement Membrane

C

Length of dotted line: 8.33 nm

PDB ID: 1bkv

Collagen III

Physics 3750. Dr. Villanueva 1 Winter 2018

at crystal

X−rays

Structures deduced (Fourier analysis, geometry …)

HUGE amount of math is done are projected

Images are made crystal layers in different ways

X−rays interact with

So ur

ce :

R an

dy R

ea de

, U ni

ve rs

ity o

f C

am br

id ge

What is it about X−rays that makes them so useful in crystallography? It is their very short wavelengths. X−rays are between 10 nm and 0.01 nm in length,

that is, between 100 and 0.1 Angstroms.

The phenomenon of X−rays was discovered in 1895 By 1914 scientists were

using X−rays to investigate

very simple: halite, or rock salt. atomic structure to be deduced crystals of minerals. The first

Halite crystal (Rock salt)

Atoms in Halite crystal

Dorothy Crowfoot Hodgkins produced the structure of cholesterol. In 1969

Thus some X−rays are on the same scale as atoms, 1 or 2 Angstroms,

with atoms and molecules, and the interactions can be analyzed as well as bonds between atoms . Being of similar size, X−rays can interact

Analysis of more complex organic compounds came later. In 1937

she unravelled the much more complex structure of the insulin molecule.

X−ray Crystallography

Introduction to Assignment 2

Physics 3750. Dr. Villanueva 2 Winter 2018

An early example of

X-ray Diffraction Analysis

Rosalyn Franklin’s “Photo 51”

1 nm

10 “rungs”

on the

ladder

Explanation & Answer

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