DR TIM EVANS / SCIENCE PHOTO LIBRARY DR TIM EVANS / SCIENCE PHOTO LIBRARY
Human topoisomerase 1/DNA complex, molecular model. Topoisomerase 1 is an enzyme that assists in uncoiling DNA. DNA (deoxyribonucleic acid) is usually stored in a supercoiled form, which must be unravelled before it can be replicated or translated into proteins. In this image, the two strands of the DNA are red and green. The secondary structure of the protein is also colour- coded: alpha helices (spirals) are dark blue, beta sheets are yellow arrows and linking regions are light blue. The arrangement of these domains gives the protein its tertiary structure, which helps to determine its function.
Model release not required. Property release not required.