Do metals inhibit acetylcholinesterase (AChE)? Implementation of assay conditions for the use of AChE activity as a biomarker of metal toxicity

• Type: Article in International Scientific Journal
• Date: 2005

Authors

Frasco, MF (Author) Other; Fournier, D (Author) Other; Carvalho, F (Author) FFUP; Guilhermino, L (Author) ICBAS

Journal

Title: Biomarkers

Vol. 10

Pages: 360-375

ISSN: 1354-750X

Publisher: Taylor & Francis

Indexing

ISI Web of Knowledge - 132 Citations

Scopus - 169 Citations

Scientific classification

FOS: Medical and Health sciences > Basic medicine

Other information

Authenticus ID: P-000-1EY

DOI: 10.1080/13547500500264660

Abstract (EN): The enzymatic activity of acetylcholinesterase (AChE) has been shown to be altered by environmental contaminants such as metals. However, the available literature illustrates a background of contradictory results regarding these effects. Therefore, the main purpose of this study was to investigate the potential of five metal ions (nickel, copper, zinc, cadmium and mercury) to inhibit AChE activity in vitro. First, to accomplish this objective, the possible interference of metals as test toxicants in the Ellman's assay, which is widely used to assess AChE activity, was studied. The potential influence of two different reaction buffers ( phosphate and Tris) was also determined. The results suggest that the selected metals react with the products of this photometric technique. It is impossible to ascertain the artefactual contribution of the interaction of the metals with the technique when measuring AChE inhibition. This constitutes a major obstacle in obtaining accurate data. The presence of phosphate ions also makes enzymatic inhibition difficult to analyse. Attending to this evidence, an assay using the substrate o-nitrophenyl acetate and Tris buffer was used to investigate the effects of metals on AChE activity. O-nitrophenyl acetate is also a substrate for esterases other than cholinesterases. It is therefore only possible to use it for the measurement of cholinesterase activity with purified enzymes or after a previous verification of the absence of other esterases in the sample tissue. Under these conditions, the results indicate that with the exception of nickel, all tested metals significantly inhibit AChE activity.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16