From 1952 - 1964, Brian Hartley pioneered work on the sequence and mechanism of the enzyme chymotrypsin in Cambridge. In 1965, he became a founding member of the MRC Laboratory of Molecular Biology, and collaborated with David Blow in determining the structure and mechanism of chymotrypsin. His group also showed that mammalian serine proteases, including the blood clotting cascade, had homologous structures and mechanisms, indicating a common evolutionary origin.

In 1974, he became Head of the Department of Biochemistry at Imperial College, converting it into a centre for molecular biology. His group developed techniques for experimental enzyme evolution, and he collaborated again with David, a biophysicist, and chemist Alan Fersht on tRNA synthetases.

However, in 1982, Brian conceived the need for a discipline - biotechnology - to exploit molecular biology breakthroughs. He left the Department of Biochemistry to set up Imperial's Centre for Biotechnology, and became a founding board member of Biogen - the longest surviving genetic engineering company. After this, Brian founded companies to make cheap bioethanol from waste hemicellulosic biomass, using genetically engineered compost heap microorganisms.

Professor Brian Hartley FRS died on 3 May 2021.