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In 1921 two researchers, Fred Banting and Charles Best, were the first to discover insulin and use it to treat diabetes.
At the time that Banting and Best were looking for a cure for diabetes, there were no alternatives but to perform their experiments using animals.
To test their theory Banting and Best used 10 dogs. They made the dogs diabetic and then investigated treatments for the diabetes. The result of their research has saved the lives of millions of people.
Injecting insulin allows
individuals with diabetes to
control their blood sugarblood sugar
The sugar (glucose) dissolved in the blood; the normal range is 4.0 - 7.8 mmol/l.
levels.
Some people have very strong opinions about testing medicines on animals. Today the use of animals is very tightly regulated and only allowed in circumstances where there are no other viable alternatives.
Using animals for biomedical research is highly regulated in the UK. The law contains these principles:
Banting and Best did not know the chemical structure of insulin. In 1955, Fred Sanger determined its amino acidamino acid
The basic building blocks of proteins. There are twenty amino acids used, in different combinations, to make every protein required by the human body.
sequence, and in 1969, Dorothy Hodgkin used X-ray crystallographyX-ray crystallography
A technique that uses the diffraction of X-rays to determine the molecular structure of a crystalline substance.
to find its three-dimensional structure.
The insulin molecule acts by attaching to cell-surface receptorsreceptors
Protein molecules attached to cells that only bind to specific molecules with a particular structure.
on its target cells. Its three-dimensional structure enables it to attach to these receptors. The shape of the insulin molecule is determined by the way the protein chains fold around each other due to hydrogen bondhydrogen bond
An intermolecular attractive force between hydrogen, when it is covalently bonded to a highly electronegative atom (fluorine, oxygen or nitrogen), and an oxygen, nitrogen or fluorine atom on another molecule.
s and disulphide bridges.
Insulin is a protein made up of two amino acid chains.
The three dimensional structure of protein is described using four categories:
Another good example is haemoglobinhaemoglobin
The protein that carries oxygen within red blood cells.
. Its quaternary structurequaternary structure
In some proteins several polypeptide chains fit together to form a larger molecule. The quaternary structure refers to the way the different polypeptide chains fit together.
is a heterotetramerHeterotetramer
protein complex formed by four subunits, where one, or more subunits, are different.
. The active conformation is formed by the arrangement of two copies of the α and two copies of the β chain. Each one binds a haem group.