⁵¹V NMR Chemical Shifts Calculated from QM/MM Models of Peroxo Forms of Vanadium Haloperoxidases

Vanadium K-edge XAS studies on the native and peroxo-forms of vanadium chloroperoxidase from Curvularia inaequalis

“…This V-N bond in the peroxo-form is shorter than in the native enzyme, being in line with the previous observation that peroxovanadate binds more strongly to the enzyme than vanadate [2]. Interestingly, a shorter V-N bond in the peroxo-intermediate was also predicted from computational studies by Geethalakshmi et al [36]. The length of the V = O bond (1.54 Å) obtained from analysis of the EXAFS is consistent with the length of V O(3) of 1.60 Å (see Table 4) observed in the crystal structure [9].…”

“…Although this seems to contradict our proposal, H-bonding to the peroxide from a nearby amine differs clearly from the suggested protonated oxygen in the peroxide-form of the enzyme. The recent QM/MM analysis on the protonation state of the peroxo-intermediates of vanadium haloperoxidases by Geethalakshmi et al [36] including the likely important cryo-water molecules suggests that maximally one vanadate oxygen is protonated, however the other possibilities cannot be excluded. As in our interpretation of the EXAFS data, the coordination geometry as observed in the X-ray structure is assumed to be also present at pH 5-6 where the enzyme is active.…”

QM/MM methods: Looking inside heme proteins biochemisty

“…If a more expensive Hamiltonian is used, for example at the Hartree-Fock (HF) or density functional (DFT) level of theory, the study will usually narrow down to one or several reaction coordinates. Recently, Thiel et al applied QM/MM methods in studies on NMR chemical shifts [24] as well as on the stability of redox eliectronmers [25]. Further recent applications include excitation energies of rhodopsin [26] and on the reactive geometry of the HIV-1 protease [27].…”

Activating tert-butyl hydroperoxide by chelated vanadates for stereoselectively preparing sidechain-functionalized tetrahydrofurans

“…From an assessment of methods, we selected Becke's three parameter Lee-Yang-Parr hybrid functional (B3LYP) [54,55] as standard for computations in combination with the 6-311++G**-basis set [56][57][58][59]. For translating results from density functional-minimized energy functions to a more tutorial bonding model, we used the natural bond orbital (NBO)-theory [60].…”