Functional Binding Surface of a β‐Hairpin VEGF Receptor Targeting Peptide Determined by NMR Spectroscopy in Living Cells

In this study, the functional interaction of HPLW peptide with VEGFR2 (Vascular Endothelial Growth Factor Receptor 2) was determined by using fast ¹⁵N‐edited NMR spectroscopic experiments. To this aim, ¹⁵N uniformly labelled HPLW has been added to Porcine Aortic Endothelial Cells. The acquisition of isotope‐edited NMR spectroscopic experiments, including ¹⁵N relaxation measurements, allowed a precise characterization of the in‐cell HPLW epitope recognized by VEGFR2.     

Effects of the menstrual cycle on the red and near-infrared optical properties of the human breast

Time-resolved reflectance and transmittance spectroscopy was applied to measure in vivo the absorption and transport scattering spectra of the female breast from 610 to 1010 nm. Three measurement configurations were used to probe different breast regions, and data were collected two or three times in each of the five phases of the menstrual cycle. The absorption spectra were best-fitted with a linear combination of the spectra of the main tissue constituents (water, lipids, oxy- and deoxyhemoglobin). This allowed us to evaluate percentage contents of water and lipids, total hemoglobin content and hemoglobin oxygen saturation. The scattering spectra were interpreted with a function derived from Mie theory, providing information on the density and average size of the tissue scatterers. Significant changes in the estimated variables were observed with measurement geometry, reflecting the heterogeneous nature of the breast, and with time, in agreement with expected physiological changes over the menstrual cycle.     

Effects of photodynamic therapy on the absorption properties of disulphonated aluminum phthalocyanine in tumor-bearing mice

Time-resolved reflectance spectroscopy was performed on tumor-bearing mice, administered with disulphonated aluminum phthalocyanine (AlS(2)Pc, 5 mg/kg body weight), before, during and after photodynamic therapy. This allowed us to evaluate the absorption spectrum of AlS(2)Pc in vivo from 610 to 700 nm, and to investigate how the therapeutic irradiation affects it. Two tumor locations (intraderma on the back and intramuscular in the leg), and two uptake times (3 and 12 h) were considered. As already observed previously, the absorption spectrum of AlS(2)Pc in vivo is centered at 680-685 nm. The irradiation causes a blue-shift of the measured line shape, more or less marked depending on the experimental conditions. A reduction in absorption is also often observed upon illumination with therapeutic light doses.     

A remark on simplicity of vertex algebras and Lie conformal algebras

I give a short proof of the following algebraic statement: in a simple vertex algebra, the underlying Lie conformal algebra is either abelian, or it is an irreducible central extension of a simple Lie conformal algebra. This provides many examples of non-finite simple Lie conformal algebras, and should prove useful for classification purposes.     

Structural Analysis of a Helical Peptide Unfolding Pathway

The analysis of the folding mechanism in peptides adopting well‐defined secondary structure is fundamental to understand protein folding. Herein, we describe the thermal unfolding of a 15‐mer vascular endothelial growth factor mimicking α‐helical peptide (QK_L10A) through the combination of spectroscopic and computational analyses. In particular, on the basis of the temperature dependencies of QK_L10A H_α chemical shifts we show that the first phase of the thermal helix unfolding, ending at around 320 K, involves mainly the terminal regions. A second phase of the transition, ending at around 333 K, comprises the central helical region of the peptide. The determination of high‐resolution QK_L10A conformational preferences in water at 313 K allowed us to identify, at atomic resolution, one intermediate of the folding–unfolding pathway. Molecular dynamics simulations corroborate experimental observations detecting a stable central helical turn, which represents the most probable site for the helix nucleation in the folding direction. The data presented herein allows us to draw a folding–unfolding picture for the small peptide QK_L10A compatible with the nucleation–propagation model. This study, besides contributing to the basic field of peptide helix folding, is useful to gain an insight into the design of stable helical peptides, which could find applications as molecular scaffolds to target protein–protein interactions.     

The First Synthesis of a Ribo-Hexos-5-Ulose: the L-Enantiomer

ABSTRACT

The title compound, previously unreported in either enantioform, and its 2,6-di-O-benzyl derivative have been synthesized through a stereocontrolled epimerization at C-2 of 6-O-protected methyl 3,4-O-isopropylidene-5-C-methoxy-β-D-galactopyranosides. The epimerization, performed through a high yielding sequence of oxidation-reduction owing to the cooperative role of the equatorial C-1 aglycon and the steric hindrance of the isopropylidene group, turned out to be completely diastereoselective. Whereas the unprotected L-ribo-hexos-5-ulose exists, as proved by NMR in D₂O, in five main tautomeric forms in a ratio of about 4:2:2:1:1, only two anomeric 1,4-furanosic forms are present at equilibrium in its 2,6-di-O-benzyl derivative, in ratios ranging from 10:1 to 7:3, depending on the prevalence of D₂O or CD₃CN in the solvent mixture.     

Preparation of L-Lyxo-Hexos-5-Ulose Through C-3 Epimerization of Bis-Glycopyranosides of L-Arabino-Hexos-5-Ulose1

Abstract

The unreported title compound and its 2,6-di-O-benzyl derivative have been prepared from methyl β-D-galactopyranoside through a sequence involving the bisglycoside methyl 2,6-di-O-benzyl-5-O-methoxv-β-D-galactopyranoside 8, the precursor of L-orabino-hexos-5-ulose, that was converted to the L-lyxo series by inversion at C-3. The inversion was achieved in acceptable yields by selective triflation, followed by displacement with benzoate, and by an oxidation/reduction sequence. Whereas 2,5-di-O-benzyl-L-lyxo-hexos-5-ulose exists entirely as a mixture of the two anomeric 1,4-furanosic forms, the unprotected hexos-5-ulose involves at equilibrium in CD₃CN/D₂O at least eight tautomers, one of which is predominant.     

Oxidation of organic films by beams of hydroxyl radicals

We have studied the oxidation of self-assembled monolayers (SAMs) of alkanes and alkenes with a thermal beam of OH radicals. The target films were produced by bonding alkane thiols and alkene thiols to a gold surface and the SAMs are mounted in a vacuum chamber at a base pressure of 10-9 Torr. Hydroxyl radicals were produced by a corona discharge in an Ar/H2O2/water mixture. The resultant molecular beam was scanned by an electrostatic hexapole and the OH radicals [4 (+/- 1) x 1011 OH radicals cm-2 sec-1] were focused onto the target SAM. All of the hydroxyl radicals impinging on the SAM surface are rotationally (J' ' 相似文献