Microproteomic analysis of 10,000 laser captured microdissected breast tumor cells using short-range sodium dodecyl sulfate-polyacrylamide gel electrophoresis and porous layer open tubular liquid chromatography tandem mass spectrometry

Precise proteomic profiling of limited levels of disease tissue represents an extremely challenging task. Here, we present an effective and reproducible microproteomic workflow for sample sizes of only 10,000 cells that integrates selective sample procurement via laser capture microdissection (LCM), sample clean-up and protein level fractionation using short-range SDS-PAGE, followed by ultrasensitive LC-MS/MS analysis using a 10 μm i.d. porous layer open tubular (PLOT) column. With 10,000 LCM captured mouse hepatocytes for method development and performance assessment, only 10% of the in-gel digest, equivalent to ～1000 cells, was needed per LC-MS/MS analysis. The optimized workflow was applied to the differential proteomic analysis of 10,000 LCM collected primary and metastatic breast cancer cells from the same patient. More than 1100 proteins were identified from each injection with >1700 proteins identified from three LCM samples of 10,000 cells from the same patient (1123 with at least two unique peptides). Label free quantitation (spectral counting) was performed to identify differential protein expression between the primary and metastatic cell populations. Informatics analysis of the resulting data indicated that vesicular transport and extracellular remodeling processes were significantly altered between the two cell types. The ability to extract meaningful biological information from limited, but highly informative cell populations demonstrates the significant benefits of the described microproteomic workflow.     

Scalable synthesis of 1-bicyclo[1.1.1]pentylamine via a hydrohydrazination reaction

The reaction of [1.1.1]propellane with di-tert-butyl azodicarboxylate and phenylsilane in the presence of Mn(dpm)(3) to give di-tert-butyl 1-(bicyclo[1.1.1]pentan-1-yl)hydrazine-1,2-dicarboxylate is described. Subsequent deprotection gives 1-bicyclo[1.1.1]pentylhydrazine followed by reduction to give 1-bicyclo[1.1.1]pentylamine. The reported route marks a significant improvement over the previous syntheses of 1-bicyclo[1.1.1]pentylamine in terms of scalability, yield, safety, and cost.     

六元gcd封闭集上Smith矩阵的整除性

我们给出了关于六元gcd封闭集S的充分必要条件,使得在整数矩阵环M_6(Z)中,定义在S上的e次幂GCD矩阵(S~e)整除e次幂LCM矩阵[S~e].这部分解决了Hong在2002年提出的一个公开问题.     

Selective anion binding by a cofacial binuclear zinc complex of a Schiff-base pyrrole macrocycle

The synthesis of the new cofacial binuclear zinc complex [Zn(2)(L)] of a Schiff-base pyrrole macrocycle is reported. It was discovered that the binuclear microenvironment between the two metals of [Zn(2)(L)] is suited for the encapsulation of anions, leading to the formation of [K(THF)(6)][Zn(2)(μ-Cl)(L)]·2THF and [Bu(n)(4)N][Zn(2)(μ-OH)(L)] which were characterized by X-ray crystallography. Unusually obtuse Zn-X-Zn angles (X = Cl: 150.54(9)° and OH: 157.4(3)°) illustrate the weak character of these interactions and the importance of the cleft preorganization to stabilize the host. In the absence of added anion, aggregation of [Zn(2)(L)] was inferred and investigated by successive dilutions and by the addition of coordinating solvents to [Zn(2)(L)] solutions using NMR spectroscopy as well as isothermal microcalorimetry (ITC). On anion addition, evidence for deaggregation of [Zn(2)(L)], combined with the formation of the 1:1 host-guest complex, was observed by NMR spectroscopy and ITC titrations. Furthermore, [Zn(2)(L)] binds to Cl(-) selectively in THF as deduced from the ITC analyses, while other halides induce only deaggregation. These conclusions were reinforced by density functional theory (DFT) calculations, which indicated that the binding energies of OH(-) and Cl(-) were significantly greater than for the other halides.     

Direct conversion of benzylic and allylic alcohols to phosphonates

Benzyl phosphonate esters often serve as reagents in Horner-Wadsworth-Emmons reactions. In most cases, they can be prepared from benzylic alcohols via formation of the corresponding halide followed by an Arbuzov reaction. To identify a more direct synthesis of phosphonate esters, we have developed a one-flask procedure for conversion of benzylic and allylic alcohols to the corresponding phosphonates through treatment with triethyl phosphite and ZnI(2).     

Selective incorporation of functional dicarboxylates into zinc metal-organic frameworks

Zinc(II) nitrate reacts with different ratios of 1,4-benzenedicarboxylic acid (H(2)bdc) and 2-halo-1,4-benzenedicarboxylic acid (H(2)bdc-X, X = Br or I) to give [Zn(4)O(bdc)(3-x)(bdc-X)(x)], in which preferential incorporation of bdc is observed. The selective incorporation is related to crystal growth rates, and the proportion of incorporated bdc-X rises with increasing reaction time.     

The relationship between redox enzyme activity and electrochemical potential-cellular and mechanistic implications from protein film electrochemistry

In protein film electrochemistry a redox protein of interest is studied as an electroactive film adsorbed on an electrode surface. For redox enzymes this configuration allows quantification of the relationship between catalytic activity and electrochemical potential. Considered as a function of enzyme environment, i.e., pH, substrate concentration etc., the activity-potential relationship provides a fingerprint of activity unique to a given enzyme. Here we consider the nature of the activity-potential relationship in terms of both its cellular impact and its origin in the structure and catalytic mechanism of the enzyme. We propose that the activity-potential relationship of a redox enzyme is tuned to facilitate cellular function and highlight opportunities to test this hypothesis through computational, structural, biochemical and cellular studies.     

Chirped pulse amplification in single mode Tm:fiber using a chirped Bragg grating

We report femtosecond pulse generation and chirped pulse amplification in Tm:fiber. A mode-locked oscillator operating in the soliton regime produced 800 fs pulses with 5 nm spectral bandwidth, at 40 pJ pulse energy. This oscillator seeded a pre-amplifier that utilizes a Raman soliton self-frequency shift to produce wavelength tunable pulses with 3 nJ energy, reduced pulse duration of 150 fs, and increased bandwidth of 30 nm. For further amplification, the pulses were stretched up to 160 ps using a chirped Bragg grating (CBG). Stretched pulses were amplified to 85 nJ after compression in single-mode Tm:fiber and recompressed with the CBG as short as 400 fs. Compressed pulses were coupled into a highly nonlinear tellurite fiber to investigate the potential of this ultrashort pulse 2-μm fiber source as a pump for mid-IR supercontinuum generation.     

Planar rectifiable curves are determined by their projections

In 1954 Steinhaus raised the question of whether a rectifiable curve is characterized by its projections. A projection onto a lineG at the pointp counts the number of points in the set which lie on the line which is perpendicular toG and passes throughp. We prove this is so, and give a method to reconstruct a closed connected rectifiable set from its projections.