Raman Spectroscopic Signature of Ectoine Conformations in Bulk Solution and Crystalline State

Abstract

Recent crystallographic results revealed conformational changes of zwitterionic ectoine upon hydration. By means of confocal Raman spectroscopy and density functional theory calculations, we present a detailed study of this transformation process as part of a Fermi resonance analysis. The corresponding findings highlight that all resonant couplings are lifted upon exposure to water vapor as a consequence of molecular binding processes. The importance of the involved molecular groups for water binding and conformational changes upon hydration is discussed. Our approach further shows that the underlying rapid process can be reversed by carbon dioxide saturated atmospheres. For the first time, we also confirm that the conformational state of ectoine in aqueous bulk solution coincides with crystalline ectoine in its dihydrate state, thereby highlighting the important role of a few bound water molecules.

Electronic Properties of Protein Destabilizers and Stabilizers: Implications for Preferential Binding and Exclusion Mechanisms

“…We are not bound by the various influences of the medium, which is particularly advantageous for the transferability of the approach to solutions with unknown dielectric constants. In addition, also, different conformational dependencies relying on the degree of hydration have been reported for Ect, which are circumvented by gas-phase calculations. − The corresponding values of E HOMO , E LUMO , and the dipole moment D for the considered species in combination with the electronegativity χ, the chemical hardness η, the electrophilicity ω, the electrofugality β E , and the nucleofugality β N are presented in Table . Further DFT calculations for a 3-isopropylacrylamide (3NIPAM) trimer as a proxy for proteins ,, with the same protocol provided values of E HOMO = –6.52 eV and E LUMO = –2.13 eV, leading to χ P = 4.33 eV and η P = 4.39 eV.…”

Bio-SAXS of single-stranded DNA-binding proteins: radiation protection by the compatible solute ectoine

“…Furthermore, in contrast to the chaotropes mentioned above, Ectoine is a so called kosmotropic or water-structure forming substance, which strengthens intermolecular hydrogen bonding. 22,23 Thus, the combination of Ectoine being a compatible solute, a kosmotrop [22][23][24] and a hydroxyl radical scavenger 21,25,26 at the same time, makes it likely to be suitable for the efficient protection of proteins during bio-SAXS based structure determination. Furthermore, Ectoines influence on G5P binding to ssDNA was characterized previously, 15 and is well understood in terms of it's protective effects for DNA against ionizing radiation, 25 UV radiation, 21 as well as repeated freeze-thaw cycles.…”

DNA Stability in Biodosimetry, Pharmacy and DNA Based Data‐Storage: Optimal Storage and Handling Conditions

“…Here we note, that both scavengers have various biotechnological applications and are with respect to a range of properties rather different. For example, DMSO is assumed to interfere with some cellular processes, [44] while Ectoine is termed a compatible solute, which can be accumulated by cells in molar concentrations, without disturbing their metabolism [24,45] . DMSO can cause denaturation of proteins., [46] while Ectoine is a kosmotrop [47] .…”

“…For example, DMSO is assumed to interfere with some cellular processes, [44] while Ectoine is termed a compatible solute, which can be accumulated by cells in molar concentrations, without disturbing their metabolism. [ 24 , 45 ] DMSO can cause denaturation of proteins., [46] while Ectoine is a kosmotrop. [47] Furthermore, the zwitterion and osmolyte Ectoine tends to accumulate at the DNA phosphate backbone [24] and to influence the water structure in its surrounding,[ 45 , 47 ] and therefore might be providing additional damage mitigating effects similar to other cryoprotectants such as glycerol or trehalose besides the actual scavenging.…”

“…[ 24 , 45 ] DMSO can cause denaturation of proteins., [46] while Ectoine is a kosmotrop. [47] Furthermore, the zwitterion and osmolyte Ectoine tends to accumulate at the DNA phosphate backbone [24] and to influence the water structure in its surrounding,[ 45 , 47 ] and therefore might be providing additional damage mitigating effects similar to other cryoprotectants such as glycerol or trehalose besides the actual scavenging. [18] However, when we invoke Occam's razor, it is reasonable to assume, that the protection of DNA by Ectoine and DMSO is most likely based on their common property, the scavenging of ROS.…”