Glutathione S-transferase (GST) enzyme from a malaria-carrying strain of mosquito, Anopheles gambiae, molecular model. GSTs detoxify foreign substances in the body of the mosquito, and this particular form has evolved to detoxify the pesticide DDT. Consequently, mosquitoes carrying the enzyme will be DDT-resistant. In this model, solid colours represent the secondary structure of the protein (spiral ribbons are alpha helices; arrows are beta sheets), and the faded tubular structure behind represents the individual atoms and bonds.