Let's Get Physical!

The polymer insulin consists of two amino acid chains (conveniently called A and B), joined together by two disulfide bonds. It is a white crystalline powder which is slightly soluble in water. It is usually delivered to the body in this dissolved form, though there have been recent attempts to deliver it as an inhaled powder.

Chemical Make-up

As mentioned before insulin is made up of two chains of amino acids. the A-chain contains 21 amino acids, while the B-chain contains 30 amino acids. Insulin is composed of 257 carbon atoms, 383 hydrogen atoms, 65 nitrogen atoms, 77 oxygen atoms, and only 6 sulfur atoms.

Method for Monomer Linking

The amino acids that make up insulin are all bonded to each other through the process of condensation. All amino acids have either a Hydrogen or Hydroxide tag sticking out in some place. In condensation, the Hydrogen and Hydroxide bond with each other to break off as a water molecule, leaving their respective amino acids with open bonding sites which they promptly use to link themselves in a peptide bond.

Click on the Animation for an Example of a Condensation (dehydration) Reaction:

All Natural

Insulin is a naturally occurring polymer. It is best known for helping control the glucose levels in humans and animals. Insulin is a hormone secreted by the pancreas. Without insulin the body would use all the glucose consumed as soon as possible. Since we don't need energy just when we eat, but throughout the whole day, insulin makes the liver and muscle cells combine the excess glucose to form glycogen. Our bodies can then break down the glycogen to produce energy when needed. If for some reason your pancreas was destroyed or removed, you would die from insulin deprivation in days.


Humalin, sometimes spelled humulin, is synthetically produced insulin. Normally there wouldn't be a need for synthetic insulin, but some people may have problem with the insulin naturally produced inside their body. Any problem with insulin can result in Type 1 diabetes. Humalin is used as a drug to help people with insulin problems process glucose. Drugs like Humulin N produce humalin inside the body so that the body can deal with glucose appropriately. Humalin N is actually a bacteria. To be more specific it is Esecherichia coli bacteria. The e. coli is genetically altered to produce humalin instead of damaging the body.



Cross-linkage occurs twice in insulin's molecular structure. The A-chain and B-chain are connect at two locations; both are formed by the cystine (Cys), one of the amino acids in insulin. Since sulfur is being used for the cross-links, the resulting bonds are disulfide bonds.

Amino Acids in Human Insulin

MLA Citations
"Condensation and Hydrolysis." Biotopics. 2007. 14 May 2008 <>.
"What is insulin and what does it do?" Free Online Health. 2008. 14 May 2008 <>
"Insulin." INCHEM. 1991. 13 May 2008
"Humulin N (Insulin (Human Recombinant)) drug description" RxList. 2008. 14 May 2008 <>
"What is Insulin?" wiseGEEK. 2008. 14 May 2008 <>
"Proteins, Amino Acids, Peptides, and Polypeptides" Scientific Physic. 2007. 14 May 2008 <>