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Two new sesquiterpene lactones, laurenolide A (1) and laurenolide B (2), along with six known compounds, palmitic acid (3), (R,R)-hexahydrofarnesyl acetone (4), trans-phytol acetate (5), cholesterol (6), cholesteryl acetate (7), cholesteryl heptadecanoate (8) were isolated from Palisada intermedia. The chemical structures of all compounds were elucidated by 1D and 2D-NMR spectroscopy and HR-ESI-MS analysis as well as compared with data in the literature. The petroleum ether, chloroform, ethyl acetate, methanol extracts and compounds 1, 2 were tested for the inhibition of two cancer cell lines MCF-7, NCI-H460 and they showed weak or none activities.

Eight platinum(II) complexes of the formula [PtCl(arylolefin)(NHC)] (2–9) with varying NHCs and arylolefin chelators have been prepared and analyzed by spectroscopic and spectrometric methods. The ...

A series of heteroleptic platinum(II) complexes of the general formula [PtX(iPrEug)(NHC)] (2-7) bearing the organometallic π/σ chelator iPrEug (isopropyl eugenoxyacetate), varying halido and NHCs ligands derived from imidazole, benzimidazole and triazole have been prepared and fully characterized by elemental analyses, ESI mass spectrometry, IR and NMR spectroscopies. Complexes 3 and 5-7 were also characterized by single-crystal X-ray diffraction. The air-stable complexes are rare examples of platinum(II) compounds containing three different types of carbon donors, i.e. aryl, carbene and olefin. Unsymmetrical NHCs lead to rotameric pairs of 4 and 5 exhibiting different NMR spectroscopic features. Spectroscopic studies also revealed that the introduction of a NHC leads to a weakening of the metal-olefin bond and strengthening of the metal-aryl bond. Backbone and thus electronic variations among the NHCs on the other hand show little influence on the bonding of the iPrEug chelator.

This study aims to synthesize the β-phase single crystal of zinc phthalocyanine (ZnPc) by using phthalonitrile process and vapor deposition. The single-crystal X-ray diffraction was used to identify the molecular structure and lattice parameters of the synthesized material. The molecular structure, frontier molecular orbitals, and IR spectroscopy of ZnPc were investigated through Time Dependent (TD)-Density Function Theory (DFT) calculations that is compared with experimental results. For the solid-state simulation, the experimental crystallographic data was used to determine band structure and density of state using DFT method on Quantum Espresso. The β-phase monoclinic single crystal of ZnPc is as a direct band gap semiconductor with the calculated energy gap of 2.1 eV, and the Fermi energy level of 2.61 eV.

Porcine trypsin was glycated with glucose and covalently immobilized through its carboxyl groups onto aminated glass beads to produce porcine immobilized glycated-trypsin (IGT). On incubation at 60 °C and pH 8, IGT retained its full activity for 8 h and 50% of its activity after 24 h. In comparison, under the same conditions porcine native trypsin lost 80% of its activity in 2 h and was completely inactivated in less than 4 h. The rate of autolysis of porcine glycated-trypsin at 37 °C was 40% that of native trypsin and with IGT there was no significant autolysis, even at elevated temperatures as high as 60 °C. Glycation significantly increased the stability of trypsin and immobilization also significantly increased the stability of trypsin. The remarkable thermostability of IGT is attributed to a synergistic effect when these two modifications are combined. Tryptic fragmentation of denatured proteins with IGT can be performed at 60 °C for shorter digestion times and with smaller amounts of enzyme than normally employed to achieve complete digestion with soluble forms of trypsin. Prior denaturation of proteins for tryptic digestion is not required with IGT as in situ denaturation and digestion can be achieved simultaneously at 60 °C with an enzyme:protein mass ratio as low as 1:1000.

A novel glycation procedure, in vacuo glycation, was used to attach glucose covalently to the lysine residues of trypsin and chymotrypsin. Glycated trypsin and glycated chymotrypsin have greatly increased thermostability compared to the native enzymes. For example, glycated bovine trypsin, incubated at 50 degrees C and pH 8.0 for 3 h, retained more than 50% of its original activity whereas the native enzyme was inactivated under the same conditions. Similarly, after incubation at 50 degrees C and pH 8.0, glycated bovine chymotrypsin retained 45% of its original activity and the native enzyme was inactivated. Glycated porcine trypsin is exceptionally thermostable and could be used to digest native ribonuclease at 70 degrees C without the need for prior denaturation. The apparent increase in the thermal stability of the glycated proteins observed in activity measurements is also reflected by an increase in the T(m) values determined with differential scanning calorimetry (DSC) and circular dichroism (CD). The glycation does not alter the activity or specificity of these enzymes.

The economical preparation of microgram quantities of 14C- labeled proteins by in vacuo methylation with methyl iodide is described. The 14C radiolabeling was achieved by the covalent attachment of [ 14C]methyl groups onto amino and imidazole groups by reaction in vacuo with [14C]methyl iodide. The method was tested by investigating the biodistribution of 14C in rats that were fed 14C-labeled human soluble cluster of differentiation 14 (CD14) protein, a receptor for bacterial lipopolysaccharide. Two other control proteins, bovine serum albumin (BSA) and casein, were also labeled with 14C and used for comparative analysis to determine the following: (i) the efficacy and cost efficiency of the in vacuo radiolabeling procedure and (ii) the extent of incorporation of the 14C label into the organs of orogastrically fed 10-day-old Sprague-Dawley rats. [14C]BSA, [ 14C]casein, and [14C]CD14 were individually prepared with specific radioactivities of 34,400, 18,800, and 163,000 disintegrations per minute (dpm)/μg, respectively. It was found that the accumulation of 14C label in the organs of [14C]CD14-fed rats, most notably the persistence of 14C in the stomach 480 min postgavage, was temporally and spatially distinct from [14C]BSA and [ 14C]casein-fed rats. © 2010 Elsevier Inc. All rights reserved.

A novel method is presented for the quantitation of peptides based on their methylation by in vacuo chemical reaction with methyl iodide. Samples of two small peptides, hexaglycine and pentaalanine, were labeled with CH(3)I and CD(3)I, representing the "unknown" and "standard" respectively, and then subjected to a series of tests using mass spectrometry to ascertain the suitability of the isotopic labels for peptide quantitation. The experiments show methyl iodide to be a very quantitative label, exhibiting a linear relationship in concentration over the dynamic range of the mass spectrometer used in the analysis (up to 4 orders of magnitude) both as pure samples and in a complex mixture of peptides. The tendency of trimethylated peptides to preferentially form a(2) fragment ions in MS(2) produces a significant increase in sensitivity, especially when the mass spectrometer is used in the MRM mode. Tests were also performed to verify the stability of the label against H/D exchange and its suitability for long-term storage, showing little degradation while in solution and during subsequent chemical processing.

Trimethyl alpha-amino derivatives of peptides (penta to deca) with a permanent positive charge on their alpha-amino groups were prepared by in vacuo reaction with iodomethane and subjected to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Compared to the unmodified peptide, the signal intensity of the trimethyl alpha-amino derivative in MALDI-MS is increased by at least an order of magnitude. Similarly, an octapeptide with a trimethylated epsilon-amino group derived from the solitary lysine residue of the B-chain of insulin also shows the same relative increase in signal intensity. Another advantage of the in vacuo methylation procedure is that trimethylation of a peptide amino group can be carried out readily with a combination of isotopes (13)CH(3)I and (12)CH(3)I or CD(3)I and CH(3)I, yielding a doublet signal either 3 or 9 units apart, respectively. The presence or absence of such a doublet signal can be used as a criterion to discriminate between peptide and non-peptide signals in the mass spectrum.

The Cry1A insecticidal crystal protein (protoxin) from six subspecies of Bacillus thuringiensis as well as the Cry1Aa, Cry1Ab, and Cry1Ac proteins cloned in Escherichia coli was found to contain 20-kilobase pair DNA. Only the N-terminal toxic moiety of the protoxin was found to interact with the DNA. Analysis of the crystal gave approximately 3 base pairs of DNA per molecule of protoxin, indicating that only a small region of the N-terminal toxic moiety interacts with the DNA. It is proposed that the DNA-protoxin complex is virus-like in structure with a central DNA core surrounded by protein interacting with the DNA with the peripheral ends of the C-terminal region extending outward. It is shown that this structure accounts for the unusual proteolysis observed in the generation of toxin in which it appears that peptides are removed by obligatory sequential cleavages starting from the C terminus of the protoxin. Activation of the protoxin by spruce budworm (Choristoneura fumiferana) gut juice is shown to proceed through intermediates consisting of protein-DNA complexes. Larval trypsin initially converts the 20-kilobase pair DNA-protoxin complex to a 20-kilobase pair DNA-toxin complex, which is subsequently converted to a 100-base pair DNA-toxin complex by a gut nuclease and ultimately to the DNA-free toxin.