Uncovering the Properties of Energy-Weighted Conformation Space Networks with a Hydrophobic-Hydrophilic Model

The conformation spaces generated by short hydrophobic-hydrophilic (HP) lattice chains are mapped to conformation space networks (CSNs). The vertices (nodes) of the network are the conformations and the links are the transitions between them. It has been found that these networks have “small-world” properties without considering the interaction energy of the monomers in the chain, i. e. the hydrophobic or hydrophilic amino acids inside the chain. When the weight based on the interaction energy of the monomers in the chain is added to the CSNs, it is found that the weighted networks show the “scale-free” characteristic. In addition, it reveals that there is a connection between the scale-free property of the weighted CSN and the folding dynamics of the chain by investigating the relationship between the scale-free structure of the weighted CSN and the noted parameter Z score. Moreover, the modular (community) structure of weighted CSNs is also studied. These results are helpful to understand the topological properties of the CSN and the underlying free-energy landscapes

Solid phase extraction and spectrophotometric determination of palladium with 2-(2-quinolylazo)-5-diethylaminobenzoic acid

Asensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with 2-(2-quinolylazo)-5-diethylaminobenzoic acid (QADEAB) and the solid phase extraction of the Pd(II) –QADEAB chelate with a reversed phase polymer-based C18 cartridge was developed. In the presence of 0.05 – 0. 5 mol/L of hydrochloric acid solution and cetyl trimethylammonium bromide (CTAB) medium, QADEAB reacts with palladium(II) to form a violet complex with a mole ratio 1:2 (palladium to QADEAB). The chelate was enriched by solid phase extraction with a reversed phase polymer-based C18 cartridge. An enrichment factor of 200 was obtained by elution of the chelate form the cartridge with the minimal amount of isopentyl alcohol. The molar absorptivity of the chelate in the isopentyl alcohol medium was 1.43 × 105 L mol-1 cm-1 at 628 nm. Beer’s law was obeyed in the range of 0.01 – 1.2 mg/mL. The relative standard deviation for eleven replicate samples at the 0.2 mg/L level was 2.18 %. The attained detection limit amounted to 0.02 mg/L in the original samples. This method was applied to the determination of palladium in environmental samples with good results

Phosphoethanolamine cytidylyltransferase ameliorates mitochondrial function and apoptosis in hepatocytes in T2DM in vitro

Liver function indicators are often impaired in patients with type 2 diabetes mellitus (T2DM), who present higher concentrations of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase than individuals without diabetes. However, the mechanism of liver injury in patients with T2DM has not been clearly elucidated. In this study, we performed a lipidomics analysis on the liver of T2DM mice, and we found that phosphatidylethanolamine (PE) levels were low in T2DM, along with an increase in diglyceride, which may be due to a decrease in the levels of phosphoethanolamine cytidylyltransferase (Pcyt2), thus likely affecting the de novo synthesis of PE. The phosphatidylserine decarboxylase pathway did not change significantly in the T2DM model, although both pathways are critical sources of PE. Supplementation with CDP-ethanolamine (CDP-etn) to increase the production of PE from the CDP-etn pathway reversed high glucose and FFA (HG&FFA)-induced mitochondrial damage including increased apoptosis, decreased ATP synthesis, decreased mitochondrial membrane potential, and increased reactive oxygen species, whereas supplementation with lysophosphatidylethanolamine, which can increase PE production in the phosphatidylserine decarboxylase pathway, did not. Additionally, we found that overexpression of PCYT2 significantly ameliorated ATP synthesis and abnormal mitochondrial morphology induced by HG&FFA. Finally, the BAX/Bcl-2/caspase3 apoptosis pathway was activated in hepatocytes of the T2DM model, which could also be reversed by CDP-etn supplements and PCYT2 overexpression. In summary, in the liver of T2DM mice, Pcyt2 reduction may lead to a decrease in the levels of PE, whereas CDP-etn supplementation and PCYT2 overexpression ameliorate partial mitochondrial function and apoptosis in HG&FFA-stimulated L02 cells

The stability and bioavailability of curcumin loaded α-lactalbumin nanocarriers formulated in functional dairy drink

There is a high demand for the development of functional foods formulated with health-promoting carotenoids. Curcumin (Cur) is one of the most promising carotenoids, but its application in functional foods especially drinks is limited due to its poor water solubility, low stability and bioavailability. Nanocarriers have shown great potential to solve these problems. In this work, Cur was loaded into nanocarriers made of self-assembly of partially hydrolyzing α-lactalbumin (α-lac). Cur functional dairy drinks were developed by adding Cur-loaded nanocarriers (nanocarriers (Cur)) into dairy drinks, and their colloidal stability and bioavailability were evaluated. The results showed that Cur exhibited intestine-responsive release behavior due to the unique nanospheres micellar structure that the hydrophobic cutting sites were buried in the core and not easily accessible to pepsin. In addition, the α-lac nanocarriers improved the stability of Cur against ultraviolet light. Furthermore, static and accelerated stability experiments showed that nanocarriers (Cur) dairy drinks possessed excellent colloidal stability. According to the sensory evaluation, the addition of nanocarriers (Cur) to dairy drinks significantly improved the perception score of stability and overall assessment. Moreover, nanocarriers (Cur) dairy drinks showed the highest Cur bioavailability. Therefore, the embedding via α-lac nanocarriers is feasible for applying Cur to functional dairy drinks and has broad prospects in the food industry

Differential Interaction of Cardiac, Skeletal Muscle, and Yeast Tropomyosins with Fluorescent (Pyrene(235)) Yeast Actin

To monitor binding of tropomyosin to yeast actin, we mutated S(235) to C and labeled the actin with pyrene maleimide at both C(235) and the normally reactive C(374). Saturating cardiac tropomyosin (cTM) caused about a 20% increase in pyrene fluorescence of the doubly labeled F-actin but no change in WT actin C(374) probe fluorescence. Skeletal muscle tropomyosin caused only a 7% fluorescence increase, suggesting differential binding modes for the two tropomyosins. The increased cTM-induced fluorescence was proportional to the extent of tropomyosin binding. Yeast tropomyosin (TPM1) produced less increase in fluorescence than did cTM, whereas that caused by yeast TPM2 was greater than either TPM1 or cTM. Cardiac troponin largely reversed the cTM-induced fluorescence increase, and subsequent addition of calcium resulted in a small fluorescence recovery. An A(230)Y mutation, which causes a Ca(+2)-dependent hypercontractile response of regulated thin filaments, did not change probe235 fluorescence of actin alone or with tropomyosin ± troponin. However, addition of calcium resulted in twice the fluorescence recovery observed with WT actin. Our results demonstrate isoform-specific binding of different tropomyosins to actin and suggest allosteric regulation of the tropomyosin/actin interaction across the actin interdomain cleft

The B73 maize genome: Complexity, diversity, and dynamics

We report an improved draft nucleotide sequence of the 2.3-gigabase genome of maize, an important crop plant and model for biological research. Over 32,000 genes were predicted, of which 99.8% were placed on reference chromosomes. Nearly 85% of the genome is composed of hundreds of families of transposable elements, dispersed nonuniformly across the genome. These were responsible for the capture and amplification of numerous gene fragments and affect the composition, sizes, and positions of centromeres. We also report on the correlation of methylationpoor regions with Mu transposon insertions and recombination, and copy number variants with insertions and/or deletions, as well as how uneven gene losses between duplicated regions were involved in returning an ancient allotetraploid to a genetically diploid state. These analyses inform and set the stage for further investigations to improve our understanding of the domestication and agricultural improvements of maize