Abstract

Widely distributed inhibitors in grapevine extracts make it difficult to improve analytical procedures for protein detection. In this study, acidity in grapevine extracts was one of the major factors inhibiting the detection of neomycin phosphotransferase II via enzyme-linked immunosorbent assay. Leaf and berry extracts with low pH (3.0 – 4.0) strongly inhibited NPT-II detection, while root and xylem sap extracts (normally pH 5.5 to 7.0) allowed the successful detection of NPT-II. The other inhibitory effect against the detection was successfully solved by heat treatment to samples extracted. Boiling leaf extract prior to ELISA, in conjunction with pH adjustment (to 7.0) was essential to improve NPT-II detection, while with berry extracts only pH adjustment was required. In the basis of above results, NPT-II protein contents in transgenic grapevine tissues possessing a NPT-II gene were successfully measured. The results here may be useful to help in evaluation of the bio-safety whether the transgenic grapevines were released or contaminated on the grapevine cultivation area by NPT-II protein detection.

Key words: pH adjustment, polyphenol, protein detection, protein inhibitor, transgenic.