抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Signaling Recognition Events with Fluorescent Sensors and Switches.

The ff94 force field that is commonly associated with the Amber simulation package is one of the most widely used parameter sets for biomolecular simulation. After a decade of extensive use and testing, limitations in this force field, such as over-stabilization of alpha-helices, were reported by us and other researchers. This led to a number of attempts to improve these parameters, resulting in a variety of "Amber" force fields and significant difficulty in determining which should be used for a particular application. We show that several of these continue to suffer from inadequate balance between different secondary structure elements. In addition, the approach used in most of these studies neglected to account for the existence in Amber of two sets of backbone phi/psi dihedral terms. This led to parameter sets that provide unreasonable conformational preferences for glycine. We report here an effort to improve the phi/psi dihedral terms in the ff99 energy function. Dihedral term parameters are based on fitting the energies of multiple conformations of glycine and alanine tetrapeptides from high level ab initio quantum mechanical calculations. The new parameters for backbone dihedrals replace those in the existing ff99 force field. This parameter set, which we denote ff99SB, achieves a better balance of secondary structure elements as judged by improved distribution of backbone dihedrals for glycine and alanine with respect to PDB survey data. It also accomplishes improved agreement with published experimental data for conformational preferences of short alanine peptides and better accord with experimental NMR relaxation data of test protein systems.

/pdf/comparison-of-multiple-amber-force-fields-and-development-of-2mpeu0hj18.pdf

Comparison of multiple Amber force fields and development of improved protein backbone parameters.

BODIPY dyes and their derivatives: syntheses and spectroscopic properties.

Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

/pdf/lanthanide-luminescence-for-functional-materials-and-bio-1w9cppwf8r.pdf

Lanthanide luminescence for functional materials and bio-sciences

Effect of N-linked glycosylation on glycopeptide and glycoprotein structure.

Asparagine-linked protein glycosylation is a prevalent protein modification reaction in eukaryotic systems. This process involves the co-translational transfer of a pre-assembled tetradecasaccharide from a dolichyl-pyrophosphate donor to the asparagine side chain of nascent proteins at the endoplasmic reticulum (ER) membrane. Recently, the first such system of N-linked glycosylation was discovered in the Gram-negative bacterium, Campylobacter jejuni. Glycosylation in this organism involves the transfer of a heptasaccharide from an undecaprenyl-pyrophosphate donor to the asparagine side chain of proteins at the bacterial periplasmic membrane. Here we provide a detailed comparison of the machinery involved in the N-linked glycosylation systems of eukaryotic organisms, exemplified by the yeast Saccharomyces cerevisiae, with that of the bacterial system in C. jejuni. The two systems display significant similarities and the relative simplicity of the bacterial glycosylation process could provide a model system that can be used to decipher the complex eukaryotic glycosylation machinery.

Asparagine-linked protein glycosylation: from eukaryotic to prokaryotic systems.

The production of fluorescent devices for the sensing and
reporting of chemical events is currently of significant importance for both chemistry and biology. More specifically, sensors directed toward the detection and measurement divalent copper have enjoyed particular attention. Our focus has been on the production of robust, small-molecule chemosensors that exhibit reversible signaling and operate in aqueous solution at neutral
pH, without the requirement for organic cosolvents. Because the intended use for such a sensor is ultimately for the measurement of environmental or biological samples, sufficient detection selectivity is of prime concern to ensure that a measurement in the appropriate concentration range can be made, even in the presence of elevated levels of competing divalent cations.

Exploiting Polypeptide Motifs for the Design of Selective Cu(II) Ion Chemosensors

Protein oligomerization: how and why.

Small proteins or protein domains generally require disulfide bridges or metal sites for their stabilization. Here it is shown that the ββα architecture of zinc fingers can be reproduced in a 23-residue polypeptide in the absence of metal ions. The sequence was obtained through an iterative design process. A key feature of the final design is the incorporation of a type II' β turn to aid in β-hairpin formation. Nuclear magnetic resonance analysis reveals that the α helix and β hairpin are held together by a defined hydrophobic core. The availability of this structural template has implications for the development of functional polypeptides.

https://science.sciencemag.org/content/sci/271/5247/342.full.pdf

Barbara Imperiali

Papers

Effect of N-linked glycosylation on glycopeptide and glycoprotein structure.

Asparagine-linked protein glycosylation: from eukaryotic to prokaryotic systems.

Exploiting Polypeptide Motifs for the Design of Selective Cu(II) Ion Chemosensors

Protein oligomerization: how and why.

Design of a monomeric 23-residue polypeptide with defined tertiary structure.