Insulin

Insulin Therapy

Diabetes mellitus may be treated by manually replacing the insulin that is missing in the blood. Of course, we need a plentiful source of insulin for use in these treatments. Fortunately, insulin from pigs (at left, PDB entry 4ins) differs from human insulin (at right, PDB entry 2hiu) by only one amino acid: a threonine at the end of the chain in human insulin is replaced by alanine in pig insulin. Insulin from cows is also very similar, differing in only three positions. Because of their similarity, these forms of insulin are also recognized by our own cells and may be used in therapy. Today, human insulin is also created by biotechnology, using engineered bacteria to produce a protein exactly identical to our own protein.

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