Multiscale analysis of enantioselectivity in enzyme-catalysed ‘lethal synthesis’ using projector-based embedding

The action of fluoroacetate as a broad-spectrum mammalian pesticide depends on the ‘lethal synthesis’ of fluorocitrate by citrate synthase, through a subtle enantioselective enolization of fluoroacetyl-coenzyme A. In this work, we demonstrate how a projection-based embedding method can be applied to calculate coupled cluster (CCSD(T)) reaction profiles from quantum mechanics/molecular mechanics optimized pathways for this enzyme reaction. Comparison of pro- R and pro- S proton abstraction in citrate synthase at the CCSD(T)-in-DFT//MM level yields the correct enantioselectivity. We thus demonstrate the potential of projection-based embedding for determining stereoselectivity in enzymatic systems. We further show that the method is simple to apply, eliminates variability due to the choice of density functional theory functional and allows the efficient calculation of CCSD(T) quality enzyme reaction barriers. </jats:p

Atomistic non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model

We present GPU-accelerated ab initio molecular dynamics simulations of nonadiabatic dynamics in the LH2 complex in full atomistic detail.</p

Ethnic land rights in Western Ghana: landlord–stranger relations in the democratic era

In Citizen and Subject (1996), Mahmood Mamdani denounced the ‘bifurcated nature’ of the African state which, in his account, imposed ethnic hierarchy and chiefly despotism on rural dwellers while reserving democratic citizenship for the urban minority. Have twenty years of ‘decentralized democracy’ in many countries washed away these distinctions? This article takes up this issue in an analysis of the politics of land allocation and landlord–stranger relations in Western Ghana. An analysis of historical trajectories, and our own field observations and interviews in two Western Region districts, suggest that at the local level, the bifurcated character of political authority that was identified by Mamdani persists in the domain of economic rights. The record also shows that state policies and institutions, rather than working to chip away at ethnic hierarchy and chiefly authority, work at least in part to reproduce these features of the local political economy. In both non-democratic and democratic eras, Ghana's central government has played an important role in shoring up chiefly and ethnic privilege in the land domain. These local hierarchies influence the practical meaning of democracy and economic liberalization for rural citizens, and should be explored more systematically in future studies of democratic and electoral politics in Ghana and elsewhere