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.

We have probed by 1H NMR spectroscopy the molecular basis of the interaction between Hoechst 33258 conjugated to a des-metalloporphyrin and a non self-complementary duplex DNA sequence, designed on the known chemical nuclease selectivity of this system. The imino NMR spectra are consistent with two distinct families of structure, that is, PORHOE binding either way along the duplex. 2D spectral, T 2, and linewidth data suggest multiple species within the two conformational families.

Binding of a porphyrin conjugate of Hoechst 33258 to DNA. II. NMR spectroscopic studies detect multiple binding modes to a 12-mer nonself-complementary duplex DNA.

Some experiments with aminodihydroxyanthraquinones

The polymerisation of methacryloyl surfactant vesicles by Fenton's reagent and their characterisation and stability to alcohol and detergents

. Diffusion-ordered NMR spectroscopy (DOSY) constructs
multidimensional spectra displaying signal strength as a function of Larmor
frequency and of diffusion coefficient from experimental measurements using
pulsed field gradient spin or stimulated echoes. Peak positions in the
diffusion domain are determined by diffusion coefficients estimated by
fitting experimental data to some variant of the Stejskal–Tanner equation, with the peak widths determined by the standard error estimated in the
fitting process. The accuracy and reliability of the diffusion domain in
DOSY spectra are therefore determined by the uncertainties in the
experimental data and thus in part by the signal-to-noise ratio of the experimental spectra measured. Here the Cramer–Rao lower bound, Monte
Carlo methods, and experimental data are used to investigate the relationship between signal-to-noise ratio, experimental parameters, and diffusion domain accuracy in 2D DOSY experiments. Experimental results confirm that sources of error other than noise put an upper limit on the improvement in diffusion domain accuracy obtainable by time averaging.

/pdf/signal-to-noise-ratio-in-diffusion-ordered-spectroscopy-how-1lyi52f0kb.pdf

Signal-to-noise ratio in diffusion-ordered spectroscopy: how good is good enough?

Accurate measurement of transverse relaxation rates in coupled spin systems is important in the study of molecular dynamics, but is severely complicated by the signal modulations caused by scalar couplings in spin echo experiments. The most widely used experiments for measuring transverse relaxation in coupled systems, CPMG and PROJECT, can suppress such modulations, but they also both suppress some relaxation contributions, and average relaxation rates between coupled spins. Here we introduce a new experiment which for the first time allows accurate broadband measurement of transverse relaxation rates of coupled protons, and hence the determination of exchange rate constants in slow exchange from relaxation measurements. The problems encountered with existing methods are illustrated, and the use of the new method is demonstrated for the classic case of hindered amide rotation and for the more challenging problem of exchange between helical enantiomers of a gold(I) complex.

/pdf/broadband-measurement-of-true-transverse-relaxation-rates-in-3xbmnwx5kt.pdf

Gareth A. Morris

Papers

Binding of a porphyrin conjugate of Hoechst 33258 to DNA. II. NMR spectroscopic studies detect multiple binding modes to a 12-mer nonself-complementary duplex DNA.

Some experiments with aminodihydroxyanthraquinones

The polymerisation of methacryloyl surfactant vesicles by Fenton's reagent and their characterisation and stability to alcohol and detergents

Signal-to-noise ratio in diffusion-ordered spectroscopy: how good is good enough?

Broadband measurement of true transverse relaxation rates in systems with coupled protons: application to the study of conformational exchange.