Electromagnetic radiation of baryons containing two heavy quarks

The two heavy quarks in a baryon which contains two heavy quarks and a light one, can constitute a scalar or axial vector diquark. We study electromagnetic radiations of such baryons, (i) \Xi_{(bc)_1} -> \Xi_{(bc)_0}+\gamma, (ii) \Xi_{(bc)_1}^* -> \Xi_{(bc)_0}+\gamma, (iii) \Xi_{(bc)_0}^{**}(1/2, l=1) -> \Xi_{(bc)_0}+\gamma, (iv) \Xi_{(bc)_0}^{**}(3/2, l=1) -> \Xi_{(bc)_0}+\gamma and (v) \Xi_{(bc)_0}^{**}(3/2, l=2) -> \Xi_{(bc)_0}+\gamma, where \Xi_{(bc)_{0(1)}}, \Xi^*_{(bc)_1} are S-wave bound states of a heavy scalar or axial vector diquark and a light quark, and \Xi_{(bc)_0}^{**}(l is bigger than 1) are P- or D-wave bound states of a heavy scalar diquark and a light quark. Analysis indicates that these processes can be attributed into two categories and the physical mechanisms which are responsible for them are completely distinct. Measurements can provide a good judgment for the diquark structure and better understanding of the physical picture.Comment: 15 pages, Late

Inhibitory Effect of Phthalic Acid on Tyrosinase: The Mixed-Type Inhibition and Docking Simulations

Tyrosinase inhibition studies are needed due to the medicinal applications such as hyperpigmentation. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics was important. We predicted the 3D structure of tyrosinase, used a docking algorithm to simulate binding between tyrosinase and phthalic acid (PA), and studied the reversible inhibition of tyrosinase by PA. PA inhibited tyrosinase in a mixed-type manner with a Ki = 65.84 ± 1.10 mM. Measurements of intrinsic and ANS-binding fluorescences showed that PA induced changes in the active site structure via indirect binding. Simulation was successful (binding energies for Dock6.3 = −27.22 and AutoDock4.2 = −0.97 kcal/mol), suggesting that PA interacts with LEU73 residue that is predicted commonly by both programs. The present study suggested that the strategy of predicting tyrosinase inhibition based on hydroxyl groups and orientation may prove useful for screening of potential tyrosinase inhibitors

Pomolic acid inhibits proliferation of human lung carcinoma cells via induction of apoptosis and suppression of cell migration and invasion

Purpose: To investigate the anti-proliferative effect of pomolic acid on lung cancer cells (A549), and theunderlying mechanism.Methods: The viability of pomolic acid-treated A549 cells was determined by MTT and colony formation assays. Cell colony formation was monitored with acridine orange/ethidium bromide (AO/EB) staining. Protein expressions of Bax and Bcl-2 were assayed by western blotting.Results: Pomolic acid suppressed the growth of A549 cells, with an half-maximal inhibitory concentration of (IC50) of 10 μM (p < 0.05). However, the IC50 of pomolic acid for normal BEAS-2B cells was 80 μM. Pomolic acid also decreased colony formation of A549 cells. At 20 μM, the percentage of A549 colonies decreased to 14 % of control. The dose-dependent cytotoxicity of pomolic acid against A549 cells was mediated via induction of apoptosis and oxidative stress. Pomolic acid treatment enhanced the expression of Bax and decreased the expression of Bcl-2 in A549 cells. Moreover, pomolic acid inhibited the migration and invasion in A549 cells in a dose-dependent manner (p < 0.05).Conclusion: These results indicate the potent anticancer effect of pomolic acid against human lung cancer cells. Thus, pomolic acid has promising potential as a lead molecule for the development of chemotherapy

Methods used to study the oligomeric structure of G protein-coupled receptors

G-protein coupled receptors (GPCRs), which constitute the largest family of cell surface receptors, were originally thought to function as monomers, but are now recognized as being able to act in a wide range of oligomeric states and indeed, it is known that the oligomerization state of a GPCR can modulate its pharmacology and function. A number of experimental techniques have been devised to study GPCR oligomerization including those based upon traditional biochemistry such as blue-native polyacrylamide gel-electrophoresis (BN-PAGE), co-immunoprecipitation and protein-fragment complementation assays, those based upon resonance energy transfer, fluorescence resonance energy transfer (FRET), time-resolved FRET, FRET spectrometry and bioluminescence resonance energy transfer (BRET). Those based upon microscopy such as fluorescence recovery after photo-bleaching (FRAP), total internal reflection fluorescence microscopy (TIRF), spatial intensity distribution analysis (SpIDA) and various single molecule imaging techniques. Finally with the solution of a growing number of crystal structures, X-ray crystallography must be acknowledged as an important source of discovery in this field. A different, but in many ways complementary approach to the use of more traditional experimental techniques, are those involving computational methods which possess obvious merit in the study of the dynamics of oligomer formation and function. Here we summarize the latest developments which have been made in the methods used to study GPCR oligomerization and give an overview of their application

Spectra of Baryons Containing Two Heavy Quarks in Potential Model

In this work, we employ the effective vertices for interaction between diquarks (scalar or axial-vector) and gluon where the form factors are derived in terms of the B-S equation, to obtain the potential for baryons including a light quark and a heavy diquark. The concerned phenomenological parameters are obtained by fitting data of $B^{(*)}-$mesons instead of the heavy quarkonia. The operator ordering problem in quantum mechanics is discussed. Our numerical results indicate that the mass splitting between $B_{3/2}(V), B_{1/2}(V)$ and $B_{1/2}(S)$ is very small and it is consistent with the heavy quark effective theory (HQET).Comment: 16 page

12α-Hy­droxy-3,27-dioxooleanano-28,13-lactone

There are two independent mol­ecules in the asymmetric unit of the title compound, C30H44O5. They comprise a triterpenoid skeleton of five six-membered rings and a five-membered lactone ring. The five six-membered rings are all trans-fused. In both independent mol­ecules the D rings adopt a slightly distorted half-chair conformation due the presence of the lactone ring while the other four six-membered rings all adopt chair conformations. The characteristic carbon–carbon double bond of the oleanoic skeleton is absent. Inter­molecular O—H⋯O hydrogen bonds between the hy­droxy and carbonyl groups occur in the crystal structure

Taphonomic analysis of the exceptional preservation of early bird feathers during the early Cretaceous period in Northeast China

Fossil soft tissues contain important and irreplaceable information on life evolution, and on the comprehensive understanding of the nature of Mesozoic ecosystems. Compared to other fossil soft tissues, Jehol Biota feathers are more commonly reported. However, taphonomic analysis of these feathers is lacking. Here, five Jehol Biota specimens of early bird Sapeornis chaoyangensis with differently preserved feathers were selected. One specimen, STM 15-36, has a complete set of extraordinarily preserved feathers. An interesting consequence was revealed by their host sediment Zr/Rb analysis that specimen STM 15-36 possesses the coarsest sediment grain size but the best-preserved feathers. More geochemical analyses of host sediments, including organic carbon isotopes and major elements, were conducted to restore the paleoenvironment during those Sapeornis’ burial. The result mainly shows that the paleoclimate when Sapeornis STM 15-36 was buried is warmer and wetter than those of the other four; STM 15-36 host sediment has a pure terrestrial-derived organic input, while the others are aquatic algae. In addition, redox-sensitive trace elements analysis indicates the lake bottom-water preserved Sapeornis STM 15-36 is anoxic and restricted, being more oxygen-depleted than those of the other four. Therefore, the transportation and burial of Sapeornis STM 15-36 were preliminarily inferred as: the carcass of Sapeornis STM 15-36 was transported rapidly into the lake by a short and strong rain flush, and then was buried quickly by the accompanying terrestrial debris; the subsequent anoxic and restricted burial environment inhibited bioturbation and hydrodynamic disturbance on Sapeornis STM 15-36 and its host sediments, allowing its whole set of feathers to be delicately preserved. This finding provides a valuable case study on understanding the taphonomy of fossil soft tissues’ exceptional preservation in Jehol Biota

Computational Prediction of Protein-Protein Interactions of Human Tyrosinase

The various studies on tyrosinase have recently gained the attention of researchers due to their potential application values and the biological functions. In this study, we predicted the 3D structure of human tyrosinase and simulated the protein-protein interactions between tyrosinase and three binding partners, four and half LIM domains 2 (FHL2), cytochrome b-245 alpha polypeptide (CYBA), and RNA-binding motif protein 9 (RBM9). Our interaction simulations showed significant binding energy scores of −595.3 kcal/mol for FHL2, −859.1 kcal/mol for CYBA, and −821.3 kcal/mol for RBM9. We also investigated the residues of each protein facing toward the predicted site of interaction with tyrosinase. Our computational predictions will be useful for elucidating the protein-protein interactions of tyrosinase and studying its binding mechanisms