Reactivity Tuning of Metal-Free Artificial Photoenzymes through Binding Site Specific Bioconjugation

The design and development of artificial metal-free photoenzymes aims to combine the selectivity of enzymatic reactions with the benefits of modern synthetic photocatalysts. Removing the need for rare earth metals and allowing for milder reaction conditions, leading to a more sustainable catalytic system. Here, we present the design of a novel artificial photoenzyme by integrating an organophotocatalytic moiety based on a donor-acceptor design into a steroid carrier protein (SCP-2L). SCP-2L possesses a hydrophobic tunnel facilitating substrate binding in aqueous media. The photocatalyst was site-selectively bound to three SCP-2L variants, possessing a non-native cysteine residue strategically placed around the hydrophobic tunnel of the protein. The three modified photoenzymes were shown to be selective for the oxidation of organic sulfides giving up to 192 turnovers.     

Problem-driven scenario generation: an analytical approach for stochastic programs with tail risk measure

Mathematical Programming - Scenario generation is the construction of a discrete random vector to represent parameters of uncertain values in a stochastic program. Most approaches to scenario...     

Thermal behavior and structural properites of plant-derived eugenyl acetate

Eugenol is an allyl chain-substituted guaiacol in the biosynthesized phenylpropanoid compound class derived from Syzygium aromaticum L. and widely used in folk medicine. Nonetheless, its pharmacological use is limited by some problems, such as instability when exposed to light and high temperature. In order to enhance stability, the eugenol molecule was structurally modified, resulting in eugenyl acetate. The eugenyl acetate’s thermal behavior and crystal structure was then characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) and compared to a commercial sample.     

Synthesis,characterization, and star polymer assembly of boronic acid end‐functionalized polycaprolactone

Boronic acid end‐functionalized polycaprolactone (PCL) polymers were synthesized by ring‐opening polymerization using a pinacol boronate ester‐containing (Bpin) initiator. The polymerization provides access to boron‐terminated polymers (i.e. Bpin‐PCL‐OH) with narrow molecular weight distributions (PDI = 1.09). Postsynthetic manipulation of the polymer's terminal hydroxyl group by copper‐catalyzed azide‐alkyne cycloaddition chemistry provides a series of bis end‐functionalized polymers with significant structural diversity at the termini. Deprotection of the boronate ester end group was accomplished with an acidic solid phase DOWEX resin. The boronate ester deprotection methodology does not result in hydrolysis of the polymeric backbone. The boronic acid‐tipped polymers were converted into star polymer assemblies using thermal dehydration and ligand‐facilitated trimerization. Thermal dehydration of (HO)₂B‐PCL‐OAc to the corresponding boroxine‐based star polymer assembly was inefficient and lead to degradation products. Ligand‐facilitated trimerization using either pyridine or 7‐azaindole as the Lewis base was efficient and mild. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Some upper bounds on the total and list chromatic numbers of multigraphs

In this paper we discuss some estimates for upper bounds on a number of chromatic parameters of a multigraph. In particular, we show that the total chromatic number for an n-order multigraph exceeds the chromatic index by the smallest t such that t! > n.     

Detection and discrimination of simple and complex sounds by hearing-impaired Belgian Waterslager canaries

Belgian Waterslager canaries (BWC) are bred to produce a distinctive low-pitched song with energy restricted to a lower range of frequencies than in other types of canaries. Previous studies have shown a high frequency hearing loss primarily above 2000 Hz that is related to hair cell abnormalities in BWC, but little is known about auditory perception in these birds. Here, frequency, duration, and intensity discrimination, temporal integration, gap detection, and discrimination of temporally reversed harmonic complexes in BWC were measured and compared to normal-hearing non-BWC. BWC had excellent frequency discrimination ability at 1000 Hz, but showed poor frequency discrimination compared to non-BWC at frequencies in the region of hearing loss. Duration and intensity discrimination were not adversely affected in BWC. Temporal integration was reduced in BWC, except at 2000 Hz. Gap detection and discrimination of temporally reversed stimuli were somewhat better in BWC than in non-BWC. Those tests that relied primarily on temporal processing were less affected by the cochlear damage in BWC than tests that probably relied more on audibility and spectral analysis. Thus, despite significant high frequency hearing loss and extensive damage along the basilar papilla, BWC retain relatively good hearing abilities under many conditions.