Triosephosphate isomerase: the perfect enzyme, but how does it work?

Insights are offered on the study by Kelpšas et al. [IUCrJ (2021). 8, 633-643], who have combined neutron and X-ray crystallography then QM (quantum mechanics) calculations on triosephosphate isomerase (TIM). The authors dissect three possible enzyme mechanisms of TIM that have arisen in the decades since the first X-ray crystal structure of this enzyme was published in 1975.