What is it about X−rays that makes them so useful in crystallography?
Biology homework help
Assignment 2 Due February 20, 2018 Details of assignment begin on p. 6
PDB shows us proteins like these
→
Collagen
Laminin
Proteoglycan
Electron microscope view of collagen fiber with those two LDL particles attached to it
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
PDB shows us proteins like these
→
Collagen
Laminin
Proteoglycan
Electron microscope view of collagen fiber with those two LDL particles attached to it
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
Source :R an dy Rea de, U nive rsity of Cam brid 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
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
Source :R an dy Rea de, U nive rsity of Cam brid 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~3.4 nm
This photo ↑ is based on an X-ray diffraction study of DNA.
It helped Francis Crick and James Watson show in 1953 that DNA is shaped like the double helix above.
For a simple explanation of how the deduction was made, see the PBS slide show, “Anatomy of Photo 51:” http://www.pbs.org/wgbh/nova/photo51/anat-flash.html
An X-ray wavelength often used in X-ray crystallography: ~ 0.136 nm (< 1/7 of a nanometer: pretty small)
Physics 3750. Dr. Villanueva 3 Winter 2018
X-ray Diffraction Analysis
Rosalyn Franklin’s “Photo 51”1 nm 10 “rungs”on the ladder~3.4 nm
This photo ↑ is based on an X-ray diffraction study of DNA.
It helped Francis Crick and James Watson show in 1953 that DNA is shaped like the double helix above.
For a simple explanation of how the deduction was made, see the PBS slide show, “Anatomy of Photo 51:” http://www.pbs.org/wgbh/nova/photo51/anat-flash.html
An X-ray wavelength often used in X-ray crystallography: ~ 0.136 nm (< 1/7 of a nanometer: pretty small)
Physics 3750. Dr. Villanueva 3 Winter 2018
http://www.pbs.org/wgbh/nova/photo51/anat-flash.htm