Room-temperature photo-induced martensitic transformation in a protein crystal

Abstract

Martensitic transformations are the first-order crystal-to-crystal phase transitions that occur mostly in materials such as steel, alloys and ceramics, thus having many technological applications. These phase transitions are rarely observed in molecular crystals and have not been detected in protein crystals. Reversibly switchable fluorescent proteins are widely used in biotechnology, including super-resolution molecular imaging, and hold promise as candidate biomaterials for future high-tech applications. Here, we report on a reversibly switchable fluorescent protein, Tetdron, whose crystals undergo a photo-induced martensitic transformation at room temperature. Room-temperature X-ray crystallography demonstrates that at equilibrium Tetdron chromophores are all in the trans configuration, with an ∼1:1 mixture of their protonated and deprotonated forms. Irradiation of a Tetdron crystal with 400 nm light induces a martensitic transformation, which results in Tetdron tetramerization at room temperature revealed by X-ray photocrystallography. Crystal and solution spectroscopic measurements provide evidence that the photo-induced martensitic phase transition is coupled with the chromophore deprotonation, but no trans–cis isomerization is detected in the structure of an irradiated crystal. It is hypothesized that protein dynamics assists in the light-induced proton transfer from the chromophore to the bulk solvent and in the ensuing martensitic phase transition. The unique properties of Tetdron may be useful in developing novel biomaterials for optogenetics, data storage and nanotechnology.

Pair distribution function study ofNi2MnGamagnetic shape memory alloy: Evidence for the precursor state of the premartensite phase

“…This transition forms the basis of the development of several technologically important ferrous and nonferrous alloys with applications ranging from ground, marine, and aerospace structures to biomedical implants, energy conversion devices, actuators, and smart structures to name just a few [1][2][3]. Martensite transitions are ubiquitous and have been observed in different classes of materials, including elemental metals (Co and group-IV metals like Ti and Zr) [5,6], ferrous and nonferrous alloys [1][2][3]7], superconducting A-15 alloys [8], ceramics [2,3], oxides (ZrO 2 ) [9], sulfides (ZnS) [10], organometallic compounds [11], amino acids [12,13], and block copolymer micelles [14]. Martensite transition was first discovered in steels where it is irreversible and athermal [1].…”