John McGeehan is a British research scientist and professor of structural biology. He is director of the Centre for Enzyme Innovation (CEI) at the University of Portsmouth and leads a research team on enzyme engineering. Plastics such as PET, while incredibly versatile, are resistant to natural breakdown and are now an increasing source of pollution in the environment. The research team aims to develop improved enzymes to breakdown plastics into their original building blocks so they can be reused as part of a circular plastics economy.