What does it look like?
Insulin (http://www.rcsb.org/pdb/explore/explore.do?pdbId=1TRZ) is a tiny peptide hormone that folds into a stable structure, braced by three strong disulfide bonds (shown in yellow). It is this compact structure of the peptide hormone that allows it to easily circulate around our body in the blood stream. The picture below shows a single insulin molecule, but the protein can also form granules consisting of six molecules arranged in a ‘donut’ like form.
What is it?
As many of you are aware, insulin is responsible for controlling our blood sugar levels. Whenever insulin is malfunctioning, our blood sugar levels can rise, resulting in Diabetes.
Where did the structure come from?
The first structure of Insulin came from pigs and was solved in the laboratory of the Nobel Laureate Dorothy Hodgkin (http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1964/). The structure was first published in 1969 after many years of hard work. (Adams, M. J., T. Blundell, E. Dodson, G. Dodson, M. Vijayan, E. Baker, M. Harding, B. Rimmer and S. Sheat. “Structure of Rhombohedral 2-zinc Insulin Crystals.” Nature 224: 491 (1969)). Dorothy continued to work on the structure of insulin in its many forms for 34 years.