An Escherichia coli enzyme involved in photoreactivation repair.

An enzyme that utilizes visible light to cleave thymine-dimers that have formed by unwanted photoreactions with ultraviolet light

Photolyase is an enzyme that binds complementary DNA strands and breaks pyrimidine dimers that are typically caused by exposure to ultraviolet light. Pyrimidine dimers occur when a pair of thymine bases or cytosine bases on the same strand of DNA bind together, resulting in a 'bulge' of the DNA structure referred to as a lesion. Photolyase has a high affinity for these lesions in the DNA and will reversibly bind and split the dimer using light-energy.