Replacement of the main chain peptide bond by imidazole ring seems to be a promising tool for the peptide-based drug design, due to the specific prototropic tautomeric as well as amphoteric properties. In this study, we present that both tautomer and pH change can cause a conformational switch of the studied residues of alanine (1–4) and dehydroalanine (5–8) with the C-terminal peptide group replaced by imidazole. The DFT methods are applied and an environment of increasing polarity is simulated. The conformational maps (Ramachandram diagrams) are presented and the stability of possible conformations is discussed. The neutral forms, tautomers τ (1) and π (2), adapt the conformations αRτ (φ, ψ = − 75°, − 114°) and C7eq (φ, ψ = − 75°, 66°), respectively. Their torsion angles ψ differ by about 180°, which results in a considerable impact on the peptide chain conformation. The cation form (3) adapts both these conformations, whereas the anion analogue (4) prefers the conformations C5 (φ, ψ = − 165°, − 178°) and β2 (φ, ψ ~ − 165°, − 3°). Dehydroamino acid analogues, the tautomers τ (5) and π (6) as well as the anion form (8), have a strong tendency toward the conformations β2 (φ, ψ = − 179°, 0°) and C5 (φ, ψ = − 180°, 180°). The preferences of the protonated imidazolium form (7) depend on the environment. The imidazole ring, acting as a donor or acceptor of the hydrogen bonds created within the studied residues, has a profound effect on the type of conformation.

Mushroom toxins are diversified range of toxic chemical compounds. They vary significantly not only in structures but also in toxicity and level of risk they pose. Some, such as amatoxins, are lethal, while others, like psilocybin are intentionally used as hallucinogens. Certain toxins, such as coprine, may be harmful only under specific conditions. Despite centuries of awareness regarding the potential toxicity of mushrooms, intoxications resulting from mushroom consumption still occur. In this review, our aim is to provide an overview of the mushroom toxins. The first part of this work presents the overview of mushroom toxins, detailing their basic features such as structures and toxicity, along with mushroom species in which they occur. In the second part of this article, we describe selected toxins grouped by their toxicity, into five categories: neurotoxins, hepatotoxins, cytotoxins, nephrotoxins and myostatins.

Ibotenic acid (IA) acts as a psychoactive compound and is one of the toxins, that occurs in certain mushrooms, especially in Amanita muscaria L. This heterocyclic compound is a structural analog of glutamic acid, a well-known neurotransmitter. Mushrooms containing psychotropic compounds are also collected deliberately for their psychedelic effects. Due to their toxicicity designing a sensor capable of detecting and monitoring the presence of ibotenic acid both in mushrooms and biological fluids of patients is of great importance. In order to enable the detection of ibotenic acid with a chemical sensor, we decided to examine interactions between potential sensor materials – small models of graphene oxide (GO) and ibotenic acid. We studied these non-covalent systems using computational methods, including both isolated and implicit solvents, subsequently utilizing semi-empirical method GFN2 (Geometries (vibrational), Frequencies, and Noncovalent interactions) followed by Density Functional Theory (DFT) calculations. The modeled complexes were stabilized mainly by strong and short H-bonds and the highest interaction energy was calculated for graphene oxide models with –COOH substituent and ibotenic acid (up to 20 kcal/mol) whereas benzene formed the weakest π-π type interactions. In comparison to the gas phase, a decrease in interaction was observed in chloroform and water. We confirmed that determining the interaction energy of non-covalent complexes GO-ibotenic acid is not significantly affected by the size of the GO model.