Next-Generation Dried Blood Spot Samplers for Protein Analysis: Describing Trypsin-Modified Smart Sampling Paper

This paper describes smart sampling paper to be used for bottom-up protein analysis. Four different manners to immobilize trypsin on cellulose were evaluated. Untreated paper, potassium-periodate-functionalized paper (with and without post-immobilization reduction) and 2-hydroxyethyl methacrylate (HEMA)/2-vinyl-4,4-dimethylazlactone (VDM)-functionalized paper were all used to immobilize trypsin. For the evaluation, Coomassie Brilliant Blue staining of proteins on paper and the BAEE trypsin activity assay needed to be modified. These methods allowed, together with data from mass spectrometric analysis of cytochrome C digestions, us to acquire fundamental insight into protein binding, and trypsin action and activity on paper. All functionalized discs bind more protein than the untreated discs. Protein binding to functionalized discs is based on both adsorption and covalent binding. Trypsin immobilized on potassium-periodate-functionalized discs exhibits the highest trypsin activity when using cytochrome C as substrate. It is proven that it is trypsin attached to paper (and not desorbed trypsin) which is responsible for the enzyme activity. The use of discs on complex biological samples shows that all functionalized discs are able to digest diluted serum; for the best-performing disc, HEMA-VDM functionalized, up to 200 high-confidence proteins are qualified, showing its potential.

METHODS OF PREPARATIVE ISOLATION OF ISOALANTHOLACTONE AND ALANTHOLACTONE FROM ELE-CAMPANE ROOT

Alantolactone and isoalantolactone accumulate in large quantities in elecampane (Inula helenium L.) roots, however, their isolation in individual states is difficult due to the same chromatographic mobility. This work presents various working methods for producing alantolactone and isoalantolactone as individual substances from elecampane root in multigram quantities. Although alantolactone and isoalantolactone can be isolated simultaneously when separated on silica gel with impregnated silver nitrate, it is more practical to obtain alantolactone or isoalantolactone from the extract of elecampane roots separately. Pure isoalantolactone can be isolated by repeated crystallization from 75% aqueous methanol. Another, faster, method of producing isoalantolactone is to react a mixture of elecampane lactones with dimethylamine or morpholine. Isoalantolactone in the form of an adduct with an amine is readily separated by crystallization and then regenerated through the preparation of a quaternary ammonium salt. Alantolactone is conveniently produced in large quantities through the oxidation of isoalantolactone in a mixture of selenium dioxide to more polar lactones, which are separated chromatographically. Hydrogen peroxide, t-butyl hydroperoxide or potassium periodate can be used as co-oxidizing agents.

Oxidative degradation of non-recycled and recycled paper

The degradation of paper-based materials involves several and complex mechanisms, such as hydrolysis and oxidation. The behaviour of different types of pulps can be very variable. In this study, the difference upon oxidation of contemporary non-recycled and recycled papers, which now constitute a considerable fibre source, is investigated. A 0.015 M potassium periodate solution is used to oxidise five types of paper, two non-recycled and three recycled, for 0.5, 1, 2 and 4 h. The effects of such oxidation treatments are evaluated in terms of carbonyl content and degree of polymerisation (DP). A modified procedure of the Szabolcs’s method and viscometry are used to measure the carbonyl content and DP, respectively. The carbonyl groups are found to increase more rapidly in the recycled papers than in the non-recycled ones. On the contrary, oxidation causes a larger decrease of the DP values in the non-recycled papers, the paper made of pure cellulose being the most sensitive in terms of depolymerisation. The DP values measured for pure cellulose paper are in line with previously reported data. Moreover, in accordance with the Ekenstam equation, the plots of the reciprocal of DP as a function of oxidation time show good linear correlations for all types of paper investigated. Pseudo rate constants are thus calculated from the slopes of these plots, those of the non-recycled papers being found to be higher than those of the recycled papers. Graphic abstract

Potassium Periodate Mediated Oxidative Cyclodesulfurization toward Benzofused Nitrogen Heterocycles

A convenient oxidative cyclodesulfurization method toward the synthesis of benzofused nitrogen heterocycles using inexpensive and readily available potassium periodate as an oxidant was developed. Upon treating isothiocyanates with ortho-substituted anilines bearing N,N-, N,O-, and N,S-bis-nucleophiles, followed by an intramolecular cyclization of the in situ generated monothioureas, substituted 2-aminobenzazole series were rapidly accessible in good to excellent yields. The protocol can accommodate various substituents on both substrates while allowing more efficient, greener, and operational simpler process relative to other oxidative coupling reactions. Tetracyclic quinazolinone derivatives were also afforded in high yields in a single preparative step and chromatography-free.

Substrate Inhibition in Ruthenium(III) Catalyzed Oxidation of Propane-1,3-diol by Periodate in Acidic Medium: A Kinetic Study

Ruthenium(III) catalyzed oxidation of propane-1,3-diol by potassium periodate was studied in aqueous perchloric acid medium. Orders of reaction with respect to concentrations of oxidant, substrate, acid and catalyst were determined. First order in oxidant and catalyst concentrations, and inverse fractional order in acid medium were observed. In addition, substrate inhibition (i.e. a decrease in reaction rate with an increase in substrate concentration) was observed. Effect of addition of salt and solvent was studied. Based on the studies of temperature variation, Arrhenius parameters were calculated. Plausible mechanism was also proposed based on observed kinetics.