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

J. Appl. Cryst.の発刊に際して

Peptides or proteins convert under some conditions from their soluble forms into highly ordered fibrillar aggregates. Such transitions can give rise to pathological conditions ranging from neurodegenerative disorders to systemic amyloidoses. In this review, we identify the diseases known to be associated with formation of fibrillar aggregates and the specific peptides and proteins involved in each case. We describe, in addition, that living organisms can take advantage of the inherent ability of proteins to form such structures to generate novel and diverse biological functions. We review recent advances toward the elucidation of the structures of amyloid fibrils and the mechanisms of their formation at a molecular level. Finally, we discuss the relative importance of the common main-chain and side-chain interactions in determining the propensities of proteins to aggregate and describe some of the evidence that the oligomeric fibril precursors are the primary origins of pathological behavior.

/pdf/protein-misfolding-functional-amyloid-and-human-disease-2w386pwb7k.pdf

Protein Misfolding, Functional Amyloid, and Human Disease

We review the dynamical mean-field theory of strongly correlated electron systems which is based on a mapping of lattice models onto quantum impurity models subject to a self-consistency condition. This mapping is exact for models of correlated electrons in the limit of large lattice coordination (or infinite spatial dimensions). It extends the standard mean-field construction from classical statistical mechanics to quantum problems. We discuss the physical ideas underlying this theory and its mathematical derivation. Various analytic and numerical techniques that have been developed recently in order to analyze and solve the dynamical mean-field equations are reviewed and compared to each other. The method can be used for the determination of phase diagrams (by comparing the stability of various types of long-range order), and the calculation of thermodynamic properties, one-particle Green's functions, and response functions. We review in detail the recent progress in understanding the Hubbard model and the Mott metal-insulator transition within this approach, including some comparison to experiments on three-dimensional transition-metal oxides. We present an overview of the rapidly developing field of applications of this method to other systems. The present limitations of the approach, and possible extensions of the formalism are finally discussed. Computer programs for the numerical implementation of this method are also provided with this article.

Dynamical mean-field theory of strongly correlated fermion systems and the limit of infinite dimensions

BIOE 402. Medical Technology Assessment. 2 or 3 hours. Bioentrepreneur course. Assessment of medical technology in the context of commercialization. Objectives, competition, market share, funding, pricing, manufacturing, growth, and intellectual property; many issues unique to biomedical products. Course Information: 2 undergraduate hours. 3 graduate hours. Prerequisite(s): Junior standing or above and consent of the instructor.

“Bioinformatics” 특집을 내면서

Accurate determination of molecular distances is fundamental to understanding the structure, dynamics, and conformational ensembles of biological macromolecules. Here we present a method to determine the full distance distribution between small (∼7 A radius) gold labels attached to macromolecules with very high-precision (≤1 A) and on an absolute distance scale. Our method uses anomalous small-angle X-ray scattering close to a gold absorption edge to separate the gold–gold interference pattern from other scattering contributions. Results for 10–30 bp DNA constructs achieve excellent signal-to-noise and are in good agreement with previous results obtained by single-energy SAXS measurements without requiring the preparation and measurement of single labeled and unlabeled samples. The use of small gold labels in combination with ASAXS read out provides an attractive approach to determining molecular distance distributions that will be applicable to a broad range of macromolecular systems.

Absolute Intramolecular Distance Measurements with Angstrom-Resolution Using Anomalous Small-Angle X-ray Scattering.

https://www.acsu.buffalo.edu/~wjzheng/Zheng_JMB2002.pdf

Protein structure prediction constrained by solution X-ray scattering data and structural homology identification.

The electron-spin-resonance $g$ factor for a spin-\textonehalf{} impurity in a dilute alloy is predicted to be logarithmically divergent at low temperatures.

Low-Temperature Anomaly of Electron-Spin Resonance in Dilute Alloys

Angle-resolved photoemission spectroscopy (ARPES) measurements on ${\mathrm{NiS}}_{2\ensuremath{-}x}{\mathrm{Se}}_{x}$ single crystals show the evolution of a narrow band near the Fermi level, which develops in the vicinity of the correlation-driven metal-insulator transition. To model the metal-insulator transition, we use a two-band Hubbard model, which has been studied extensively to describe transition-metal compounds, and use a dynamical mean-field-theory approach. The ARPES data are in striking qualitative agreement with the predictions of the model. Comparison of our data to the calculations suggests a possible mechanism for the metal-insulator transition with Se substitution in which both charge-transfer and hole-doping effects are present.

Metal-insulator transition in NiS 2 − x Se x and the local impurity self-consistent approximation model

Several algorithms are available to reconstruct low-resolution electron density maps of biological macromolecules from small-angle solution scattering data. These algorithms have been extensively applied to proteins and protein complexes. Here, we demonstrate their applicability to nucleic acids by reconstructing a set of RNA and DNA molecules of known three-dimensional structure from their small-angle X-ray scattering profiles. The overall size and shape of the molecules get reproduced well in all tested cases. Furthermore, we show that the generated bead models can be used as inputs for electrostatic calculations. The number of ions bound under different solution conditions computed from numerical solutions of the Poisson–Boltzmann equation for bead models agrees very well with results of calculations on all atom models derived from crystallography. The predictions from Poisson–Boltzmann theory also agree generally well with experimentally determined ion binding numbers.

/pdf/low-resolution-models-for-nucleic-acids-from-small-angle-x-2oplazzl15.pdf

Sebastian Doniach

Papers

Absolute Intramolecular Distance Measurements with Angstrom-Resolution Using Anomalous Small-Angle X-ray Scattering.

Protein structure prediction constrained by solution X-ray scattering data and structural homology identification.

Low-Temperature Anomaly of Electron-Spin Resonance in Dilute Alloys

Metal-insulator transition in NiS 2 − x Se x and the local impurity self-consistent approximation model

Low-resolution models for nucleic acids from small-angle X-ray scattering with applications to electrostatic modeling