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

Coherence transfer by isotropic mixing: Application to proton correlation spectroscopy

A two-dimensional nuclear overhauser experiment with pure absorption phase in four quadrants☆

https://zenodo.org/record/45375/files/article.pdf

Natural abundance nitrogen-15 NMR by enhanced heteronuclear spectroscopy

The widespread use of controlled molecular-level motion in key natural processes suggests that great rewards could come from bridging the gap between the present generation of synthetic molecular systems, which by and large rely upon electronic and chemical effects to carry out their functions, and the machines of the macroscopic world, which utilize the synchronized movements of smaller parts to perform specific tasks. This is a scientific area of great contemporary interest and extraordinary recent growth, yet the notion of molecular-level machines dates back to a time when the ideas surrounding the statistical nature of matter and the laws of thermodynamics were first being formulated. Here we outline the exciting successes in taming molecular-level movement thus far, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion. We also highlight some of the issues and challenges that still need to be overcome.

Synthetic molecular motors and mechanical machines.

Saturating irradiation far off-resonance can lead to diminution in the water signal seen in MRI, giving rise to magnetization transfer contrast. This results from transfer of magnetization between "solid" protons with restricted motion, which give rise to a band some tens of kilohertz wide, and the narrow signal from mobile protons. In the work reported here a high-power pulse spectrometer, which can detect signals from both mobile and immobile protons, was used to investigate the dynamics of magnetization transfer in cartilage in vitro. Magnetization transfer in modified Hoffman-Forsen inversion transfer experiments was well-described by a single rate constant model; full analytical solutions are offered for the resultant biexponential magnetization recovery curves. The use of pulsed methods to generate magnetization contrast may in some circumstances offer advantages over the steady-state saturation methods used hitherto.

Direct Observation of the Magnetization Exchange Dynamics Responsible for Magnetization Transfer Contrast in Human Cartilage in Vitro

Oligomers of the achiral amino acid Aib adopt helical conformations in which the screw-sense may be controlled by a single N-terminal residue. Using crystallographic and NMR techniques, we show that the left- or right-handed sense of helical induction arises from the nature of the β-turn at the N terminus: the tertiary amino acid l-Val induces a left-handed type II β-turn in both the solid state and in solution, while the corresponding quaternary amino acid l-α-methylvaline induces a right-handed type III β-turn.

Left-Handed Helical Preference in an Achiral Peptide Chain Is Induced by an l-Amino Acid in an N-Terminal Type II β-Turn

https://pubs.rsc.org/en/content/articlepdf/2017/cc/c7cc04423b

Ultraclean pure shift NMR

A simple approach to single-channel quadrature detection

A review. A review on the use of diffusion ordered spectroscopy (DOSY) to study mixts. In DOSY, the results of pulsed field gradient spin echo expts. are analyzed to det. diffusion coeffs. for the individual signals in a spectrum, and hence to distinguish between the signals of different components in a mixt. In most applications, two-or three-dimensional spectra are synthesized in which signals are dispersed in one dimension according to their diffusion coeffs. DOSY uses std. spectrometer hardware and sample handling, requiring only the addnl. software for data anal. and spectrum synthesis. [on SciFinder (R)]

Gareth A. Morris

Papers

Direct Observation of the Magnetization Exchange Dynamics Responsible for Magnetization Transfer Contrast in Human Cartilage in Vitro

Left-Handed Helical Preference in an Achiral Peptide Chain Is Induced by an l-Amino Acid in an N-Terminal Type II β-Turn

Ultraclean pure shift NMR

A simple approach to single-channel quadrature detection

Diffusion-ordered spectroscopy (DOSY).