Tuning Maps for Two-Photon Absorption Cross Sections of Canonical and Noncanonical Fluorescent Protein Chromophores.

Two-photon absorption (2PA) spectroscopy, which involves the simultaneous absorption of a pair of photons, is an important area of research in chemical biology, where a diversity of biological chromophores have been explored for 2PA applications. This work offers a perspective on how electrostatic interactions influence the 2PA response of fluorescent protein (FP) chromophores, demonstrating the role of their surrounding environment in modulating 2PA optical properties. In this work, we present electrostatic tuning maps, created by placing partial charges along the van der Waals radii of eight different chromophores: Green FP (neutral and anion), Red FP (neutral and anion), mBlueberry FP, Kusabira orange FP, and two noncanonical chromophores, a hydroxyquinolone derivative, and the chromophore of Gold FP.

A variant on the CREST iMTD algorithm for noncovalent clusters of flexible molecules.

Conformational ensemble generation and the search for the global minimum conformation are important problems in computational chemistry. In this work, a variant on the conformer-rotamer ensemble sampling tool (CREST) iterative metadynamics (iMTD) algorithm designed for determining structural ensembles and energetics of noncovalent clusters of flexible molecules is presented. We term this new algorithm a low-energy diversity-enhanced variant on CREST, or LEDE-CREST.