PubMed · 9511557
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D J Harnick. 1995. Impression material for rapid palatal expanders.. https://pubmed.ncbi.nlm.nih.gov/9511557/
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Two different immobilized chymotrypsin derivatives were used to synthesize kyotorphin, using N-benzoyl-L-tyrosine ethyl ester and L-arginine ethyl ester as substrates, in water-DMF media. The first was adsorbed onto Celite particles and the second was multipoint covalently attached into polyacrylamide gel. In all cases, the conversion of the carboxyl substrate was carried out in first-order reaction conditions. For the adsorbed enzyme, the reaction kinetics deviated from first-order likely due to a fast irreversible inactivation of enzyme during the reaction time even at low DMF concentration (15-20% v/v). The covalent attachment of enzyme resulted in elimination of irreversible activity loss by organic solvent up to 60% (v/v) of DMF. The catalytic activity of the covalent derivative was conserved as appropriate for performing a synthetic reaction up to 60% v/v of DMF (in comparison to 30% v/v for the adsorbed derivative), showing a clear improvement in its stability against reversible denaturation by this solvent. The selectivity of the synthetic reaction was slightly enhanced (from 40-50%) with the increase in DMF concentration to 80% v/v, but it was significantly improved (to 80%) when L-argininamide was used as nucleophile.
Denaturing gradient gel electrophoresis (DGGE) is believed to be the most powerful pre-screening method for mutation detection currently available, being used mostly on an exon-by-exon basis. Broad-range DGGE for the analysis of multiple fragments or an entire gene is rarely applied. We and others have already shown that one or two DGGE conditions are usually sufficient to analyse an entire gene. Conditions, however, have never been profoundly tested and compared with alternative methods suggested in the literature. Trying to do so in this study, we found significant differences between the various gel systems. The optimal conditions we found for broad-range DGGE include 9% polyacrylamide for the gel, a denaturing gradient with a difference of 30-50% between the lowest and the highest concentration of denaturant, and electrophoresis in 0.5x TAE buffer at a voltage >100 V and <200 V.
Microspheres containing poly(acrylic acid) and beta-cyclodextrin or maltose were prepared by a w/o solvent evaporation technique. The dispersed aqueous phase contained poly(acrylic acid) (800 mg) and beta-cyclodextrin or maltose (0, 200 or 800 mg). Food-grade olive oil was the continuous phase. Microsphere particle size was consistently between 15 and 25 microm, and carbohydrate content was in good agreement with that added to the dispersed phase in all cases. Two dyes, phenolphthalein and rhodamine B, having different solubility characteristics and strengths of association with beta-cyclodextrin, were selected for loading and in vitro release studies. Microspheres were loaded by soaking in a saturated propan-2-ol solution of the appropriate dye (6 h). Microsphere dye content ranged between 2.8 and 4.8 mg/g microspheres for phenolphthalein and between 2.2 and 3.7 mg/g for rhodamine B. Release studies were performed in phosphate buffer (pH 7.4; 37 degrees C). No difference in the release profile of either dye was observed between microspheres. The failure of microspheres containing beta-cyclodextrin in particular, to alter the in vitro release kinetics of either dye may be due to a number of factors and include: (i) limited cross-linking giving rise to a the rapid hydration of the polymer matrix; (ii) perturbation of the dye-beta-cyclodextrin complex by oil and/or organic solvent residues; and (iii) conformational changes/steric hindrance of the beta-cyclodextrin cavity (due to its covalent binding with PAA) resulting in a reduction in its ability to form inclusion complexes.