In this new method for determining urinary protein, the reaction is complete within 10 min at 37 degrees C. This method is applicable to automated as well as manual measurements. Protein concentration and absorbance at 600 nm are linearly related throughout a wide range of concentrations, 10 to 16 000 mg/L. However, the chromogenicity of the gamma-globulins in this method is 70% of that of albumin, as estimated from results by a biuret method. Within-run CVs were less than 3.3%; the day-to-day CV was 2.9%. Errors due to interfering components in urine are less than 2%. The normal range for urinary protein as measured by this method was from 28 to 141 mg/day. Results by this method (y) and by a trichloroacetic acid-biuret method (x) correlated well (n = 80, r = 0.995; y = 0.99x - 2.9).
Previously, O-selective phosphorylation on polymer supports in the N-unprotected phosphoramidite method could not be carried out because the amino groups of dA and dC have high reactivity toward tervalent phosphorus(III)-type phosphitylating reagents. In this paper, we developed a new coupling strategy named the "activated phosphite method" in which the phosphitylation is mediated by phosphite triester intermediates 1. Application of 1-hydroxybenzotriazole as the promoter to the solid-phase synthesis resulted in excellent O-selectivity of more than 99.7%. This O-selectivity was explained by the frontier molecular orbital interactions between the reactive intermediates and the nucleophiles such as the amino or hydroxyl groups of nucleosides. Furthermore, longer oligonucleotides were synthesized not only by a manual operation but also by a DNA synthesizer. The utility of our new method was demonstrated by the successful synthesis of a base-labile modified oligodeoxyribonucleotide having 4-N-acetyldeoxycytidine residues. Finally, DNA 20-mers containing dA or dC could be synthesized in good yields by use of a combined reagent of 6-trifluoromethyl-1-hydroxybenzotriazole and benzimidazolium triflate.
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