Interaction of nitrite with ferric protoglobin from - an interesting model for spectroscopic studies of the haem-ligand interaction.

Protoglobin from (Pgb) is a dimeric globin belonging to the same lineage of the globin superfamily as globin-coupled sensors. A putative role in the scavenging of reactive nitrogen and oxygen species has been suggested as a possible adaptation mechanism of the host organism to different gaseous environments in the course of evolution. A combination of optical absorption, electronic circular dichroism (ECD), resonance Raman (rRaman), and electron paramagnetic resonance (EPR) reveal the unusual reaction of ferric Pgb with nitrite.

Epimeric Mixture Analysis and Absolute Configuration Determination Using an Integrated Spectroscopic and Computational Approach-A Case Study of Two Epimers of 6-Hydroxyhippeastidine.

Structural elucidation has always been challenging, and misassignment remains a stringent issue in the field of natural products. The growing interest in discovering unknown, complex natural structures accompanies the increasing awareness concerning misassignments in the community. The combination of various spectroscopic methods with molecular modeling has gained popularity in recent years.

Improving the IR spectra alignment algorithm with spectra deconvolution and combination with Raman or VCD spectroscopy.

The relative stereochemistry of organic molecules can be determined by comparing theoretical and experimental infrared (IR) spectra of all isomers and assessing the best match. For this purpose, we have recently developed the IR spectra alignment (IRSA) algorithm for automated optimal alignment. IRSA provides a set of quantitative metrics to identify the candidate structure that agrees best with the experimental spectrum.

Vibrational Optical Activity Study of Four Antibiotic (Lipo)glycopeptides: Vancomycin, Oritavancin, Dalbavancin, and Teicoplanin.

The antibiotic glycopeptide class, of which vancomycin is the original compound, has received due attention over the past few decades in search of antibiotics to overcome resistances developed by bacteria. Crucial for the understanding and further development of glycopeptides that possess desired antibacterial effects is the determination of their conformational behavior, as this sheds light on the mechanism of action of the compound. Among others, vibrational optical activity (VOA) techniques (vibrational circular dichroism and Raman optical activity) can be deployed for this, but the question remains to what extent these spectroscopic techniques can provide information concerning the molecular class under investigation.

GLB-3: A resilient, cysteine-rich, membrane-tethered globin expressed in the reproductive and nervous system of Caenorhabditis elegans.

The popular genetic model organism Caenorhabditis elegans (C. elegans) encodes 34 globins, whereby the few that are well-characterized show divergent properties besides the typical oxygen carrier function. Here, we present a biophysical characterization and expression analysis of C.

Insights in the vibrational optical activity spectra of the antibiotic vancomycin in DMSO.

Vibrational circular dichroism (VCD) and Raman optical activity (ROA) are two spectroscopic techniques that are sensitive towards the conformational behaviour of molecules, and are often complementary herein. In this work we pursue the determination of the conformational ensemble of the antibiotic glycopeptide vancomycin in DMSO through comparison of experimental and computational spectra, both for VCD and ROA. ROA is found to be highly suitable for the task, identifying an ensemble that strongly resembles the NMR conformation.

Paving the way to conformationally unravel complex glycopeptide antibiotics by means of Raman optical activity.

It is crucial for fundamental physical chemistry techniques to find their application in tackling real-world challenges. Hitherto, Raman optical activity (ROA) spectroscopy is one of the examples where a promising future within the pharmaceutical sector is foreseen, but has not yet been established. Namely, the technique is believed to be able to contribute in investigating the conformational behaviour of drug candidates.

Tackling Stereochemistry in Drug Molecules with Vibrational Optical Activity.

Chirality plays a crucial role in drug discovery and development. As a result, a significant number of commercially available drugs are structurally dissymmetric and enantiomerically pure. The determination of the exact 3D structure of drug candidates is, consequently, of paramount importance for the pharmaceutical industry in different stages of the discovery pipeline.

Exploring machine learning methods for absolute configuration determination with vibrational circular dichroism.

The added value of supervised Machine Learning (ML) methods to determine the Absolute Configuration (AC) of compounds from their Vibrational Circular Dichroism (VCD) spectra was explored. Among all ML methods considered, Random Forest (RF) and Feedforward Neural Network (FNN) yield the best performance for identification of the AC. At its best, FNN allows near-perfect AC determination, with accuracy of prediction up to 0.

Employing complementary spectroscopies to study the conformations of an epimeric pair of side-chain stapled peptides in aqueous solution.

Understanding the conformational preferences of free ligands in solution is often necessary to rationalize structure-activity relationships in drug discovery. Herein, we examine the conformational behavior of an epimeric pair of side-chain stapled peptides that inhibit the FAD dependent amine oxidase lysine specific demethylase 1 (LSD1). The peptides differ only at a single stereocenter, but display a major difference in binding affinity.

Synthesis, Structure and Photophysical Properties of a New Class of Inherently Chiral Boron(III) Chelates-The tert-Leucine Complexes.

A new family of boron(III) chelates is introduced whereby molecular chirality, confirmed by circular dichroism, is imported during synthesis such that isolation of the diastereoisomers does not require separation procedures. The photophysical properties of two members of the family have been examined: the N,O,O-salicylaldehyde-based derivative shows pronounced intramolecular charge-transfer character in fluid solution and is weakly fluorescent, with a large Stokes shift. The corresponding 2-methylamino-benzaldehyde-derived N,N,O-chelate absorbs and fluoresces in the visible region with a much smaller Stokes shift.

A combined Raman optical activity and vibrational circular dichroism study on artemisinin-type products.

Artemisinin and two of its derivatives, dihydroartemisinin and artesunate, which are front line drugs against malaria, were investigated using Raman optical activity (ROA) and vibrational circular dichroism (VCD) experiments, both supported by density functional theory (DFT) level calculations. The experimental techniques combined with DFT calculations could show that dihydroartemisinin was present as an epimeric mixture in solution. In addition, an approximation of the epimeric ratio could be extracted which was in agreement with the ratio obtained by 1H-NMR spectroscopy.