Author(s): Wang S; Orabi EA; Baday S; Bernèche S; Lamoureux G;

Proteins of the Amt/MEP family facilitate ammonium transport across the membranes of plants, fungi, and bacteria and are essential for growth in nitrogen-poor environments. Some are known to facilitate the diffusion of the neutral NH(3), while others, notably in plants, transport the positively charged NH(4)(+). On the basis of the structural data for Amt ...

Article GUID: 22631217

Author(s): Orabi MAA; Orabi EA; Awadh AAA; Alshahrani MM; Abdel-Wahab BA; Sakagami H; Hatano T;

Polyphenols have a variety of phenolic hydroxyl and carbonyl functionalities that enable them to scavenge many oxidants, thereby preserving the human redox balance and preventing a number of oxidative stress-related chronic degenerative diseases. In our ongoing investigation of polyphenol-rich plants in search of novel molecules, we resumed the investigat ...

Article GUID: 38001804

Author(s): Orabi MAA; Orabi EA; Abdel-Sattar ES; English AM; Hatano T; Elimam H;

An ellagitannin monomer, lythracin M (1), and a dimer, lythracin D (2), along with eight known monomers (3-10) were isolated from Lawsonia inermis (Lythraceae) leaves. Lythracin M (1) is a C-glycosidic ellagitannin with a flavogallonyl dilactone moiety that participates in the creation of a ?-lactone ring with the anomeric carbon of the glucose core. Lyth ...

Article GUID: 36423882

Author(s): Orabi EA; English AM;

Long associated with cell death, hydrogen peroxide (H2O2) is now known to perform many physiological roles. Unraveling its biological mechanisms of action requires atomic-level knowledge of its association with proteins and lipids, which we address here. High-level [MP2(full)/6-311++G(3df,3pd)] ab initio calculations reveal skew rotamers as the lowest-ene ...

Article GUID: 33356279

Author(s): Orabi EA; Davis RL; Lamoureux G;

Cation-p interactions play important roles in molecular recognition and in the stability and function of proteins. However, accurate description of the structure and energetics of cation-p interactions presents a challenge to both additive and polarizable force fields, which are rarely designed to account for the complexation of charged groups with aromat ...

Article GUID: 31652004

Author(s): Orabi EA; Peslherbe GH;

S-Sulfhydration of cysteine to the Cys-SSH persulfide is an oxidative post-translational modification that plays an important regulatory role in many physiological systems. Though hydrogen persulfide (H2S2) has recently been established as a signaling and cellular sulfhydration reagent, the chemistry and chemical biology of persulfides remain poorly explo ...

Article GUID: 31297500

Author(s): Orabi EA; English AM;

Oxidation and protonation/deprotonation strongly impact intermolecular noncovalent interactions. For example, S-aromatic interactions are stabilized up to three-fold in the gas phase on oxidation of the sulfur ligand or protonation/deprotonation of the aromatic. To probe if such stabilizing effects are additive and to model interactions of oxidized methio ...

Article GUID: 31214677

Author(s): Orabi EA; English AM;

Noncovalent interactions between Met and aromatic residues define a common Met-aromatic motif in proteins. Met oxidation to MetOn (n = 1 sulfoxide, n = 2 sulfone) alters protein stability and function. To predict the chemical and physical consequences of such oxidations, we modeled the chemistry and redox properties of MetOn-aromatic complexes in depth fo ...

Article GUID: 30168822