Mechanisms of metalloenzymes studied by quantum chemical methods

Abstract

1. Introduction 922. Methods and models 932.1 Density Functional Theory 932.2 Chemical models 983. Examples of mechanisms studied 1043.1 Photosystem II 1053.2 Cytochrome c oxidase 1083.3 Manganese catalase 1123.4 Ribonucleotide reductase 1143.5 Methane mono-oxygenase 1193.6 Methyl coenzyme M reductase 1223.7 Intra- and extradiol dioxygenases 1243.8 Tyrosinase and catechol oxidase 1263.9 Amino-acid hydroxylases 1303.10 Isopenicillin N synthase 1323.11 Cytochrome c peroxidase 1343.12 Copper-dependent amine oxidase 1363.13 Galactose oxidase 1384. Summary and conclusions 1385. Acknowledgements 1406. References 140The study of metalloenzymes using quantum chemical methods of high accuracy is a relatively new field. During the past five years a quite good understanding has been reached concerning the methods and models to be used for these systems. For systems containing transition metals hybrid density functional methods have proven both accurate and computationally efficient. A background on these methods and the accuracy achieved in benchmark tests are given first in this review. The rest of the review describes examples of studies on different metalloenzymes. Most of these examples describe mechanisms where dioxygen is either formed, as in photosystem II, or cleaved as in many other enzymes life cytochrome c oxidase, ribonucleotide reductase, methane mono-oxygenase and tyrosinase. In the descriptions below high emphasis is put on the actual determination of the transition states, which are the key points determining the mechanisms.