A Microreactor with Thousands of Subcompartments: Enzyme‐Loaded Liposomes within Polymer Capsules

Fully loaded : Noncovalent anchoring of liposomes into polymer multilayered films with cholesterol‐modified polymers allows the preparation of capsosomes—liposome‐compartmentalized polymer capsules (see picture). A quantitative enzymatic reaction confirmed the presence of active cargo within the capsosomes and was used to determine the number of subcompartments within this novel biomedical carrier system.

     

Investigation of polyelectrolyte adsorption by means of a novel concept based upon the use of model surfaces and model polyelectrolytes

A concept to study the influence of molecular parameters in the adsorption of polyelectrolytes is presented. Characteristic for this approach is the use of model surfaces and model polyelectrolytes. The properties of both the surfaces and polyelectrolytes can be varied in a well defined way and over a broad range. First experiments show that the method is able to give structural information about the adsorbed polyelectrolytes. The method is very sensitive, adsorption experiments with polyelectrolyte concentrations in the region of micromoles per litre are possible.     

Triggering Activity of Catalytic Rod‐Like Supramolecular Polymers

Supramolecular polymers based on benzene‐1,3,5‐tricarboxamides (BTAs) functionalized with an L ‐ or D ‐proline moiety display high catalytic activity towards aldol reactions in water. High turnover frequencies (TOF) of up to 27×10^?4 s^?1 and excellent stereoselectivities (up to 96 % de, up to 99 % ee) were observed. In addition, the catalyst could be reused and remained active at catalyst loadings and substrate concentrations as low as 0.1 mol % and 50 mM , respectively. A temperature‐induced conformational change in the supramolecular polymer triggers the high activity of the catalyst. The supramolecular polymer’s helical sense in combination with the configuration of the proline (L ‐ or D ‐) is responsible for the observed selectivity.     

Spectroscopic Examinations of Hydrogen Bonding in Hydroxy‐Functionalized ADMET Chemistry

Wide‐angle X‐ray scattering (WAXS) and temperature‐dependent Fourier transform infrared spectroscopy (FTIR) spectroscopy are used to study hydrogen bonding interactions of a hydroxyl‐functionalized polyethylene (PE) prepared by acyclic diene metathesis (ADMET) chemistry. The hydroxyl polymer exhibits an orthorhombic unit cell structure with characteristic reflection planes at (110) and (200), comparable to pure crystalline PE. These data unequivocally demonstrate that the OH branch is excluded from the PE lamellae. Furthermore, the polymer melts 100 °C higher than all previous analogous polymers possessing precision placed long aliphatic branches that also are excluded from PE lamellae. Temperature‐dependent FTIR spectroscopy from ambient to 150 °C, followed by cooling to 125 °C supports exclusion of the hydroxyl group from the crystalline lattice. It is concluded that these hydroxyl groups form stable physical networks in the amorphous region via hydrogen bonding and are important for the overall morphology of such polymers.

     

Identification and relative quantification of adenosine to inosine editing in serotonin 2c receptor mRNA by CE

A new method has been developed allowing the identification and relative quantification of different forms of mRNA after RNA editing. This method was applied to the serotonin 2c receptor mRNA that potentially exhibits 32 different forms after adenosine to inosine editing at five different sites located in a row of 13 nucleotides. CE was used to characterize fluorescently labeled ssDNA molecules on the basis of their conformational polymorphism. The relative amount of these 32 mRNA forms has been estimated by measuring the fluorescence intensity of each individual DNA strand. Accuracy of quantification was established by diluting one form into another or into a mixture of cDNA, showing linear and precise proportion of each form (0.06 相似文献   

Proteomic Analysis of Plasma Membrane Vesicles

A simple and scalable method is presented for harvesting, purification, and on‐chip processing of mammalian plasma membrane vesicles (PMVs) optimized for downstream proteome analysis. After immobilization on a microfluidic flowcell of PMVs, the embedded membrane proteins are proteolytically digested, and the peptides harvested and analyzed by LC‐MS/MS. Over 93 % of the detected proteins are plasma‐membrane‐derived.

     

Statistical Encounters with Complex B-Splines

Complex B-splines as introduced in Forster et al. (Appl. Comput. Harmon. Anal. 20:281–282, 2006) are an extension of Schoenberg’s cardinal splines to include complex orders. We exhibit relationships between these complex B-splines and the complex analogues of the classical difference and divided difference operators and prove a generalization of the Hermite–Genocchi formula. This generalized Hermite–Genocchi formula then gives rise to a more general class of complex B-splines that allows for some interesting stochastic interpretations.      

Cluster analysis application identifies muscle characteristics of importance for beef tenderness

Background

Unsaturated fatty acids are susceptible to oxidation and damaged chains are removed from glycerophospholipids by phospholipase A₂. De-acylated lipids are then re-acylated by lysophospholipid acyltransferase enzymes such as LPCAT1 which catalyses the formation of phosphatidylcholine (PC) from lysoPC and long-chain acyl-CoA.

Results

Activity of LPCAT1 is inhibited by Ca²⁺, and a Ca²⁺-binding motif of the EF-hand type, EFh-1, was identified in the carboxyl-terminal domain of the protein. The residues Asp-392 and Glu-403 define the loop of the hairpin structure formed by EFh-1. Substitution of D³⁹² and E⁴⁰³ to alanine rendered an enzyme insensitive to Ca²⁺, which established that Ca²⁺ binding to that region negatively regulates the activity of the acyltransferase amino-terminal domain. Residue Cys-211 of the conserved motif III is not essential for catalysis and not sufficient for sensitivity to treatment by sulfhydryl-modifier agents. Among the several active cysteine-substitution mutants of LPCAT1 generated, we identified one to be resistant to treatment by sulfhydryl-alkylating and sulfhydryl-oxidizer agents.

Conclusion

Mutant forms of LPCAT1 that are not inhibited by Ca²⁺ and sulfhydryl-alkylating and ?Coxidizing agents will provide a better understanding of the physiological function of a mechanism that places the formation of PC, and the disposal of the bioactive species lysoPC, under the control of the redox status and Ca²⁺ concentration of the cell.