I wouldn't go as far as saying that they are redefining how enzymes work... all molecules experience tunneling of some sort. Hydrogen very often tunnels through rotational barriers and even through the nucleus as with ammonia; however, all this is described in the wavefunction of the molecule... what I guess the article is trying to say is that, their approximation methods are underestimating the importance of tunneling in their models. As with the case with anything larger than helium, wavefunctions need to be approximated using a variety of methods