Laser ablation-ICP-MS assay development for detecting Cd- and Zn-binding proteins in Cd-exposed Spinacia oleracea L.

Cadmium is one of the most widespread metals which is highly toxic, and can enter the human food chain directly via accumulation in nutritional plants. To better understand the transport and protein binding capabilities of heavy metals we have investigated cadmium uptake in Spinacia oleracea L., a typical nutritional plant with a high cadmium uptake susceptibility. We have elaborated a new strategy for the screening of cadmium-containing proteins which consists of the extraction of proteins by application of an ultrasonic homogeniser and separation of the metal-binding proteins by use of native PAGE. For comparison, denaturing PAGE has been investigated, too. Laser ablation (LA) was utilised as a sample introduction system for inductively coupled plasma mass spectrometry (ICP-MS) detection of the metals in the proteins after PAGE separation and blotting onto membranes. In total, three protein bands have been detected which contain higher levels of cadmium among which one contains zinc also.