Arthur Mallay Lesk, is a protein science researcher, who is a professor of biochemistry and molecular biology at the Pennsylvania State University in University Park. Lesk received a bachelor's degree, magna cum laude, from Harvard University in 1961. He received his doctoral degree from Princeton University in 1966. He also received a master's degree from the University of Cambridge in the United Kingdom in 1999. Lesk has made significant contributions to the study of protein evolution. He and Cyrus Chothia, working at the Medical Research Council (UK) Laboratory of Molecular Biology in Cambridge, United Kingdom, discovered the relationship between changes in amino-acid sequence and changes in protein structure by analyzing the mechanism of evolution in protein families.This discovery has provided the quantitative basis for the most successful and widely used method of structure prediction, known as homology modelling.