We have developed a rapid, selective, and sensitive fluorometric procedure for measuring tryptophan in serum. This assay is based on the facile reaction of tryptophan with aqueous formaldehyde; the concentration of the amino acid is measured from the diminution in its fluorescence as the reaction proceeds. Compared to other assay procedures, this procedure has the advantage of being sensitive t...

Extensive efforts have been made to develop anti-HIV drugs from potential HIV-1 protease inhibitor1'2) since the protease inhibitors have been proven to produce immature and non-infectious viruses3'4). In order to find HIV-1 protease inhibitors and study the kinetics of inhibition of the protease, many assay methods have been devised using the protease produced by genetic engineering techniques...

A facile fluorometric assay using D-kynurenine as a substrate was utilized for evaluating the inhibition of D-amino acid oxidase (DAAO), which is one of the products of a susceptibility gene for schizophrenia, by commercial antipsychotic drugs, namely, chlorpromazine (CPZ), carbamazepine, sulpiride, quetiapine, and imipramine. CPZ inhibited DAAO (65.8 ± 13.2 μM, n = 3) as reported previously, a...

A gradient elution column chromatography technique and a step-wise technique succeeded in differentiating between IAA and the citrus auxin. IAA was eluted ahead of the citrus auxin in both systems. The highest Avena curvature ever obtained from the citrus auxin occurred after the auxin had passed through the 2 purification techniques and a paper chromatography step. This is probably due to the ...

In this paper we describe the microcomputer-aided determination of cell proliferation kinetics and doubling times utilizing a crystal violet assay and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay in microtitration plates. The analysis of spectrophotometric data provides the doubling times at any time of incubation. Plots of doubling time versus time of incubation giv...