High‐pressure microfluidisation pretreatment disaggregate peanut protein isolates to prepare antihypertensive peptide fractions

High‐pressure microfluidisation (HPM) pretreatment was applied to increase in vitro antihypertensive activity of peanut peptide fractions (PPF). The morphology of protein in aqueous dispersion revealed that peanut protein isolate (PPI) disaggregated at relatively low pressure (≤120 MPa) and re‐aggregated at relatively high pressures (150–210 MPa). The treated pressure of 120 MPa could lead to the most disaggregation of PPI. Small peptides contents, trichloroacetic acid‐nitrogen soluble index (TCA‐NSI) and degree of hydrolysis (DH) of peanut protein hydrolysates (PPH) all reached the highest at 120 MPa. Consequently, it possessed the highest angiotensin converting enzyme (ACE) and renin inhibitory activity. The highest surface hydrophobicity occurred at 120 MPa pretreatment samples. Thirty‐nine oligopeptides at 120 MPa pretreatment were identified by ultra‐performance liquid chromatography‐quadrupole time‐of‐flight (UPLC‐Q‐TOF) mass spectrometer combined with Progenesis QI for Proteomics software compared with 29 and 35 at control and 210 MPa, respectively. This meant that disaggregation of PPI at 120 MPa resulted in the release of new hydrophobic peptide.     

Electrostatic Control of Structure in Self‐Assembled Membranes

Self‐assembling peptide amphiphiles (PAs) can form hierarchically ordered membranes when brought in contact with aqueous polyelectrolytes of the opposite charge by rapidly creating a diffusion barrier composed of filamentous nanostructures parallel to the plane of the incipient membrane. Following this event, osmotic forces and charge complexation template nanofiber growth perpendicular to the plane of the membrane in a dynamic self‐assembly process. In this work, we show that this hierarchical structure requires massive interfacial aggregation of PA molecules, suggesting the importance of rapid diffusion barrier formation. Strong PA aggregation is induced here through the use of heparin‐binding PAs with heparin and also with polyelectrolytes of varying charge density. Small angle X‐ray scattering shows that in the case of weak PA‐polyelectrolyte interaction, membranes formed display a cubic phase ordering on the nanoscale that likely results from clusters of PA nanostructures surrounded by polyelectrolyte chains.     

Mass spectrometry of peptides and proteins from human blood

It is difficult to convey the accelerating rate and growing importance of mass spectrometry applications to human blood proteins and peptides. Mass spectrometry can rapidly detect and identify the ionizable peptides from the proteins in a simple mixture and reveal many of their post‐translational modifications. However, blood is a complex mixture that may contain many proteins first expressed in cells and tissues. The complete analysis of blood proteins is a daunting task that will rely on a wide range of disciplines from physics, chemistry, biochemistry, genetics, electromagnetic instrumentation, mathematics and computation. Therefore the comprehensive discovery and analysis of blood proteins will rank among the great technical challenges and require the cumulative sum of many of mankind's scientific achievements together. A variety of methods have been used to fractionate, analyze and identify proteins from blood, each yielding a small piece of the whole and throwing the great size of the task into sharp relief. The approaches attempted to date clearly indicate that enumerating the proteins and peptides of blood can be accomplished. There is no doubt that the mass spectrometry of blood will be crucial to the discovery and analysis of proteins, enzyme activities, and post‐translational processes that underlay the mechanisms of disease. At present both discovery and quantification of proteins from blood are commonly reaching sensitivities of ～1 ng/mL. © 2010 Wiley Periodicals, Inc., Mass Spec Rev 30:685–732, 2011     

The ability of zinc to inhibit the sporulation and viability of Clostridium sporogenes and growth of other bacteria

The objective of this study was to investigate the influence of zinc on the sporulation and viability of Clostridium sporogenes and on the growth of other bacteria. When 0.5% ZnCl₂ was added to a sporulation medium, it completely inhibited C. sporogenes (PA 3679) sporulation for up to 3 weeks. At concentrations of 0.5% and 1.0%, ZnCl₂ not only completely inactivated the vegetative cell viability (>7.0 Log reduction) but also significantly reduced the spore viability (<2.1 Log reduction) of C. sporogenes. Taken together, it was concluded that zinc blocks C. sporogenes sporulation by damaging (or killing) vegetative cells and probably by interfering with the biosynthesis of spore components. In addition to the inhibitory effect on the sporulation and viability of C. sporogenes, ZnCl₂ was found to have a broad antimicrobial spectrum against all Gram‐positive and Gram‐negative spoilage and pathogenic bacteria tested. The minimal inhibitory concentration for inhibiting the bacteria ranged between 3.7 and 7.4 mm . Therefore, we expect that this compound or a combination thereof has a potential as a surface‐cleaning agent or disinfectant.     

Improved tumor targetability of Tat-conjugated PAMAM dendrimers as a novel nanosized anti-tumor drug carrier

The generation 4-poly-amidoamine-dendrimers (PAMAM G4 dendrimer, P) was conjugated to Tat peptide (Tat, T), a cell-penetrating peptide, in search of an efficient anti-tumor drug delivery vehicle for cancer therapy. In this study, we synthesized BODIPY-labeled Tat-Conjugated PAMAM dendrimers (BPTs) as a novel nanosized anticancer drug carriers and systemically investigated their biodistribution and the tumor accumulation in Sarcoma 180-bearing mice. In addition, the uptake and the cytotoxicity to S180 cells of BPTs thereof were evaluated. The unmodified dendrimer (BP) showed a soon clearance from the blood stream and nonspecific accumulation in tumor. In contrast, the Tat-modified dendrimer, BPT(64) with appropriate particle size showed a better retention in blood and could be accumulated effectively in tumor tissue via the enhanced permeability and retention (EPR) effect. Moreover, BPTs with a high Tat modification rate was accumulated more effectively in tumor tissue. In vitro experiments, these BPTs displayed low cytotoxicity on S180 cells and high uptake to S180 cells. These findings indicate that the nanoparticulate system on the basis of Tat-conjugated PAMAM dendrimers is safer and effective in the concentration range (below 20?μg/ml) to be used as a carrier of anti-tumor drugs for tumor targeting by intravenous administration.     

深层水平井双聚胺基钻井液技术研究与应用

针对大庆油田深层致密气埋藏深,储层砾岩、火山岩裂缝发育,水敏性强,钻井过程中易发生漏失、垮塌、缩径及高温钻井液性能变差等复杂,且深层水平井钻进会带来摩阻、携岩和储层污染及使用油基钻井液存在成本高、后期环保压力大等难题,在分析总结前人研究成果及经验基础上,从致密气藏地质特征及深层水平井钻井难点出发,明确了钻井液技术对策,通过开展聚胺和聚醚多元醇"双聚"抑制、封堵防塌剂的研究,配合自主研制的新型高效随钻封堵材料,研发出一套适合于深层致密气藏水平井施工的双聚胺基钻井液技术。室内研究及现场应用表明,该钻井液具有较强的封堵防塌、井眼清洁和润滑防卡能力,抗温达180℃以上,有效地解决了深层水平井漏失、垮塌、携屑、润滑问题和储层保护问题,保证了深层水平井的顺利施工,创造了大庆油田深层水平井钻井周期最短(109d),井深最深(5048 m),水平段最长(969.22 m),井底温度最高(180℃)等几项新纪录,完全满足了徐家围子地区深层致密气藏的钻探需求,为深层水平井安全、快速、高效钻井提供了技术保障。     

Initial Molecular Recognition Steps of McjA Precursor during Microcin J25 Lasso Peptide Maturation

Microcin J25 (MccJ25) has emerged as an excellent model to understand the maturation of ribosomal precursor peptides into the entangled lasso fold. MccJ25 biosynthesis relies on the post‐translational modification of the precursor McjA by the ATP‐dependent protease McjB and the lactam synthetase McjC. Here, using NMR spectroscopy, we showed that McjA is an intrinsically disordered protein without detectable conformational preference, which emphasizes the active role of the maturation machinery on the three‐dimensional folding of MccJ25. We further showed that the N‐terminal region of the leader peptide is involved in interaction with both maturation enzymes and identified a predominant interaction of V43–S55 in the core McjA sequence with McjC. Moreover, we demonstrated that residues K23–Q34 in the N‐terminal McjA leader peptide tend to adopt a helical conformation in the presence of membrane mimics, implying a role in directing McjA to the membrane in the vicinity of the lasso synthetase/export machinery. These data provide valuable insights into the initial molecular recognition steps in the MccJ25 maturation process.