β-diketonates are customary bidentate ligands in highly luminescent ternary europium complexes, such as Eu(β-diketonate)3(L)2, where L stands for a nonionic ligand. Usually, the syntheses of these complexes start by adding, to an europium salt such as EuCl3(H2O)6, three equivalents of β-diketonate ligands to form the complexes Eu(β-diketonate)3(H2O)2. The nonionic ligands are subsequently added...

Cyclophellitol aziridines have found wide application as mechanism-based, covalent, and irreversible inhibitors of retaining glycosidases. These compounds, like their parent compound, cyclophellitol (a natural product β-glucosidase inactivator), make use the mechanism action glycosidases, which process substrate through formation a transient covalent intermediate. In contrast, inverting other m...

We determine the structure of the set of intermediate β-shifts of finite type. Specifically, we show that this set is dense in the parameter space ∆ = {(β,α) ∈ R2 : β ∈ (1,2) and 0 ≤ α ≤ 2−β}. This generalises the classical result of Parry from 1960 for greedy and (normalised) lazy β-shifts.

Perfringolysin O (PFO), a bacterial cholesterol-dependent cytolysin, binds a mammalian cell membrane, oligomerizes into a circular prepore complex (PPC) and forms a 250-Å transmembrane β-barrel pore in the cell membrane. Each PFO monomer has two sets of three short α-helices that unfold and ultimately refold into two transmembrane β-hairpin (TMH) components of the membrane-embedded β-barrel. In...

β-Lactamases threaten the clinical use of carbapenems, which are considered antibiotics of last resort. The classical mechanism of serine carbapenemase catalysis proceeds through hydrolysis of an acyl-enzyme intermediate. We show that class D β-lactamases also degrade clinically used 1β-methyl-substituted carbapenems through the unprecedented formation of a carbapenem-derived β-lactone. β-Lacto...

background: preterm birth is a major health problem that leads to infant morbidity and mortality. the main goal of this study was to find the relationship between social determinants of health and preterm delivery. methods: a prospective longitudinal cohort study was carried out on 500 pregnant women in their 24th to 28th gestational weeks in 2012. the pregnant women filled out a self-report qu...

β-Lactamases are the major reason β-lactam resistance is seen in Gram-negative bacteria. To combat this resistance mechanism, β-lactamase inhibitors are currently being developed. Presently, there are only three that are in clinical use (clavulanate, sulbactam and tazobactam). In order to address this important medical need, we explored a new inhibition strategy that takes advantage of a long-l...

Metallo-β-lactamases inactivate most β-lactam antibacterials, and much attention has been paid to their catalytic mechanism. One issue of controversy has been whether β-lactam hydrolysis generally proceeds through an anionic intermediate bound to the active-site Zn(II) ions or not. The formation of an intermediate has not been shown conclusively in imipenemase (IMP) enzymes to date. Here, we pr...