%0 Journal Article
%T Spin-orbit coupling and zero-field splitting of the high-spin ferric enzyme-substrate complex: Protocatechuate 3,4-dioxygenase complexed with 3,4-dihydroxyphenylacetate
%A LingLing L¨¹
%A YuanCheng Zhu
%A XiaoFang Wang
%A GuoFang Zuo
%A Feng Guo
%A SuRui Zhao
%A YongCheng Wang
%J Chinese Science Bulletin
%@ 1861-9541
%D 2013
%I 
%R 10.1007/s11434-012-5316-7
%X We used density functional calculations to investigate the electronic origins of the magnetic properties of the high-spin ferric enzyme-substrate complex protocatechuate 3,4-dioxygenase (3,4-PCD). The calculated g-tensors show that ligand-to-metal charge transfer transitions are from the protocatechuate (PCA) and Tyr408 orbitals to the Fe d¦Ð orbitals, which lead to x- and y-polarized transitions. These polarized transitions require a spin-orbit coupling (SOC) matrix element in the z-direction, L z (z = z¡ä), resulting in a g z¡ä value of 2.0158, significantly deviating from 2.0023. A large zero-field splitting parameter value of +1.147 cm 1 is due to ¦¤S =  1 spin-orbit mixing with the quartet states for the sextet ground state, accounting for around 73% of the SOC contribution. The SOC matrix elements indicate that the high-spin d5 system Fe(III), 3,4-PCD-PCA is a weak spin-crossover compound with an SOC of 31.56 cm 1.
%K 3
%K 4-PCD-PCA
%K g-tensor
%K zero-field splitting
%K spin-orbit coupling
%U http://link.springer.com/article/10.1007/s11434-012-5316-7