Practical screening of mercury contamination in fish tissue.

The increased release of heavy metals over the last century poses an unknown detriment to our ecosystem. Already. poisoning by toxic heavy metals has been documented in a number of species, including man. Estimation of the toxicological context of this release requires screening methods that rapidly process large numbers of samples with minimal cost, effort and ecological impact. We now describe a practical colorimetric kit to quantify mercuric ion in tissue, and demonstrate its application to screen fish. Advantageously, this test can easily be amended for field use and catch-and-release programs.

Screening hydrolysis over two-phases.

A new assay is described that monitors hydrolysis with the concurrent transfer of a solvatochromic dye across an oil-water barrier. Through the appropriate design, this transfer is accompanied by a 10(6) gain in fluorescence. This response can be used to effectively screen hydrolytic activity at high-throughput. Using this method, microunits of alkaline phosphatase, glucosidases, as well as several common proteases can be visually detected within an hour through concentration over a 200:1 volumetric ratio of aqueous to organic phases. Development of a water-solublizing protecting group extends this methodology to screen a wide range of processes that undergo cleavage of a covalent bond.

A rapid method to identify exo-protease inhibitors.

A new approach to the evaluation of exo-protease inhibitor candidates is presented. The application of new water-soluble substrates that release organic-soluble fluorescent groups upon proteolytic cleavage allows amplification of the assay signal via concentration of the cleavage product. A combinatorial library of disubstituted xanthenes designed to resemble a known inhibitor was screened and a new HLE inhibitor (Ki = 79 microM) was identified.