The binding of precipitant ions in the tetragonal crystals of hen egg white lysozyme

Abstract

The bonds between lysozyme molecules and precipitant ions in single crystals grown with chlorides of several metals are analysed on the basis of crystal structure data. Crystals of tetragonal hen egg lysozyme (HEWL) were grown with chlorides of several alkali and transition metals (LiCl, NaCl, KCl, NiCl₂ and CuCl₂) as precipitants and the three-dimensional structures were determined at 1.35?Å resolution by X-ray diffraction method. The positions of metal and chloride ions attached to the protein were located, divided into three groups and analysed. Some of them, in accordance with the recently proposed and experimentally confirmed crystal growth model, provide connections in protein dimers and octamers that are precursor clusters in the crystallization lysozyme solution. The first group, including Cu⁺², Ni⁺² and Na⁺¹ cations, binds specifically to the protein molecule. The second group consists of metal and chloride ions bound inside the dimers and octamers. The third group of ions can participate in connections between the octamers that are suggested as building units during the crystal growth. The arrangement of chloride and metal ions associated with lysozyme molecule at all stages of the crystallization solution formation and crystal growth is discussed.

Communicated by Ramaswamy H. Sarma     

Abiotic Photophosphorylation Model Based on Abiogenic Flavin and Pteridine Pigments

A model for abiotic photophosphorylation of adenosine diphosphate by orthophosphate with the formation of adenosine triphosphate was studied. The model was based on the photochemical activity of the abiogenic conjugates of pigments with the polymeric material formed after thermolysis of amino acid mixtures. The pigments formed showed different fluorescence parameters depending on the composition of the mixture of amino acid precursors. Thermolysis of the mixture of glutamic acid, glycine, and lysine (8:3:1) resulted in a predominant formation of a pigment fraction which had the fluorescence maximum at 525 nm and the excitation band maxima at 260, 375, and 450 nm and was identified as flavin. When glycine in the initial mixture was replaced with alanine, a product formed whose fluorescence parameters were typical to pteridines (excitation maximum at 350 nm, emission maximum at 440 nm). When irradiated with the quasi-monochromatic light (over the range 325–525 nm), microspheres in which flavin pigments were prevailing showed a maximum photophosphorylating activity at 375 and 450 nm, and pteridine-containing chromoproteinoid microspheres were most active at 350 nm. The positions and the relative height of maxima in the action spectra correlate with those in the excitation spectra of the pigments, which point to the involvement of abiogenic flavins and pteridines in photophosphorylation.     

Critical Role of S1PR1 and Integrin β4 in HGF/c-Met-mediated Increases in Vascular Integrity

Vascular endothelial cell (EC) barrier integrity is critical to vessel homeostasis whereas barrier dysfunction is a key feature of inflammatory disorders and tumor angiogenesis. We previously reported that hepatocyte growth factor (HGF)-mediated increases in EC barrier integrity are signaled through a dynamic complex present in lipid rafts involving its receptor, c-Met (1). We extended these observations to confirm that S1PR1 (sphingosine 1-phosphate receptor 1) and integrin β4 (ITGB4) are essential participants in HGF-induced EC barrier enhancement. Immunoprecipitation experiments demonstrated HGF-mediated recruitment of c-Met, ITGB4 and S1PR1 to caveolin-enriched lipid rafts in human lung EC with direct interactions of c-Met with both S1PR1 and ITGB4 accompanied by c-Met-dependent S1PR1 and ITGB4 transactivation. Reduced S1PR1 expression (siRNA) attenuated both ITGB4 and Rac1 activation as well as c-Met/ITGB4 interaction and resulted in decreased transendothelial electrical resistance. Furthermore, reduced ITGB4 expression attenuated HGF-induced c-Met activation, c-Met/S1PR1 interaction, and effected decreases in S1P- and HGF-induced EC barrier enhancement. Finally, the c-Met inhibitor, XL880, suppressed HGF-induced c-Met activation as well as S1PR1 and ITGB4 transactivation. These results support a critical role for S1PR1 and ITGB4 transactivation as rate-limiting events in the transduction of HGF signals via a dynamic c-Met complex resulting in enhanced EC barrier integrity.     

Planar Cell Polarity Pathway Regulates Nephrin Endocytosis in Developing Podocytes

The noncanonical Wnt/planar cell polarity (PCP) pathway controls a variety of cell behaviors such as polarized protrusive cell activity, directional cell movement, and oriented cell division and is crucial for the normal development of many tissues. Mutations in the PCP genes cause malformation in multiple organs. Recently, the PCP pathway was shown to control endocytosis of PCP and non-PCP proteins necessary for cell shape remodeling and formation of specific junctional protein complexes. During formation of the renal glomerulus, the glomerular capillary becomes enveloped by highly specialized epithelial cells, podocytes, that display unique architecture and are connected via specialized cell-cell junctions (slit diaphragms) that restrict passage of protein into the urine; podocyte differentiation requires active remodeling of cytoskeleton and junctional protein complexes. We report here that in cultured human podocytes, activation of the PCP pathway significantly stimulates endocytosis of the core slit diaphragm protein, nephrin, via a clathrin/β-arrestin-dependent endocytic route. In contrast, depletion of the PCP protein Vangl2 leads to an increase of nephrin at the cell surface; loss of Vangl2 functions in Looptail mice results in disturbed glomerular maturation. We propose that the PCP pathway contributes to podocyte development by regulating nephrin turnover during junctional remodeling as the cells differentiate.     

Two-component covalent inhibitor

Inhibitors that covalently damage proteins or nucleic acids offer great potency, but are difficult to rationally design and suffer from poor specificity. Here we outline a general concept for constructing covalent inhibitors, called the two-component covalent inhibitor (TCCI). The approach takes advantage of two ligand analogs equipped with pre-reactive groups. Binding of the analogs to the adjacent sites of a target biopolymer brings the pre-reactive groups in close proximity and causes their interaction followed by covalent damage of the target. In the present study we used light-activated pre-reactive groups to inactivate a DNA polymerase. It was found that the efficiency of a traditional single-component inhibitor was greatly reduced in the presence of a non-target protein, while the TCCI was not significantly affected. Our findings suggest that TCCI approach has advantages in inactivation of biopolymers in complex multi-component systems.     

Phase II Study of Concurrent Capecitabine and External Beam Radiotherapy for Pain Control of Bone Metastases of Breast Cancer Origin

Background

Pain from bone metastases of breast cancer origin is treated with localized radiation. Modulating doses and schedules has shown little efficacy in improving results. Given the synergistic therapeutic effect reported for combined systemic chemotherapy with local radiation in anal, rectal, and head and neck malignancies, we sought to evaluate the tolerability and efficacy of combined capecitabine and radiation for palliation of pain due to bone metastases from breast cancer.

Methodology/Principal Findings

Twenty-nine women with painful bone metastases from breast cancer were treated with external beam radiation in 10 fractions of 3 Gy, 5 fractions a week for 2 consecutive weeks. Oral capecitabine 700 mg/m² twice daily was administered throughout radiation therapy. Rates of complete response, defined as a score of 0 on a 10-point pain scale and no increase in analgesic consumption, were 14% at 1 week, 38% at 2 weeks, 52% at 4 weeks, 52% at 8 weeks, and 48% at 12 weeks. Corresponding rates of partial response, defined as a reduction of at least 2 points in pain score without an increase in analgesics consumption, were 31%, 38%, 28%, 34% and 38%. The overall response rate (complete and partial) at 12 weeks was 86%. Side effects were of mild intensity (grade I or II) and included nausea (38% of patients), weakness (24%), diarrhea (24%), mucositis (10%), and hand and foot syndrome (7%).

Conclusions/Significance

External beam radiation with concurrent capecitabine is safe and tolerable for the treatment of pain from bone metastases of breast cancer origin. The overall and complete response rates in our study are unusually high compared to those reported for radiation alone. Further evaluation of this approach, in a randomized study, is warranted.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01784393","term_id":"NCT01784393"}}NCT01784393{"type":"clinical-trial","attrs":{"text":"NCT01784393","term_id":"NCT01784393"}}NCT01784393     

Fauna of bumblebees (Hymenoptera: Apidae: Bombus Latreille) in the mainland part of Arkhangelsk Region,NW Russia

The focus of this study is to present bumblebee fauna of Arkhangelsk Region (north-western Russia). This research is based on the museum collections and materials collected by the authors. Collecting localities and data of faunistic records are given in the species list. We include 34 species in the fauna of bumblebees of Arkhangelsk Region. The regional fauna is dominated by Transpalaearctic species. Bumblebee fauna in the study region has low specificity. The recent distribution of bumblebee species in the study region is a result of post-glacial immigration.     

Synthesis and Antioxidant Activity of Carane and Pinane Based Sulfenimines and Sulfinimines

The synthesis of sulfenimines and sulfinimines has been carried out with 10‐hydroxyisocamphylthiol. The configuration of the compounds has been deduced by methods of NMR, DFT calculations and X‐ray diffraction analysis. The cytotoxic, antioxidant and membrane‐protective activity of the synthesized compounds as well as of the previously obtained sulfenimines and sulfinimines based on 4‐caranethiol have been determined.     

In Pursuit of Closed‐Loop Supply Chains for Critical Materials: An Exploratory Study in the Green Energy Sector

A closed‐loop supply chain (CLSC) is considered not only an important solution for ensuring sustainable exploitation of materials, but also a promising strategy for securing long‐term availability of materials. The latter is especially highlighted in the materials criticality discourse. Critical raw materials (CRMs), being exposed to supply disruptions, create an uncertain operational environment for many industries, particularly for green energy technologies that employ multiple CRMs. However, recycling rates of CRMs are very low and engagement of companies in CLSC for CRM is limited. This study examines factors influencing CLSC for CRM development in photovoltaic panels and wind turbine technologies. The aim is to analyze how the factors manifest themselves in different companies along the supply chain and to identify enabling and bottleneck conditions for implementation of CLSC for CRM. The novelty of the study is twofold: the focus on material rather than product flows, and examination of factors from a multiactor perspective. The evidence obtained suggests that the manufacturing companies and reverse supply‐chain operators engaged in the study take different perspectives (product vs. material) regarding development of CLSC for CRM and thus emphasize different factors. The findings underline the need for interactions between supply‐chain actors, a sound competitive environment for recycling processes, and investment in technologies and infrastructure development if CLSC for CRM is to be developed. The paper provides implications for practitioners and policy makers for implementation of CLSC for CRM, and suggests prospects for further research.