24 carat gold test tubes

Perhaps a more inert material should be used for test tubes. As we've discussed before chemicals leaching from test tubes can lead to enzyme inhibition. It has also been demonstrated that plastics can interfere with results in cell culture and even more recently it has been shown that plastics can affect protein and DNA measurements by UV absorption measurements, by as much as 300%.

It's the plastic, stupid!

One of the original baybz alerted us of this paper in science which discusses contaminants found in plastic that can inhibit enzymes. We use disposable plastics a lot in the lab, from tips to eppies , without thinking too much about it. There are a few people who religiously believe that you should not change any of your plastic supplies (tips/tubes) when repeating an experiment. Well these people maybe on to something as this Canadian team from Alberta has shown as much as 40% inhibition of hMOA-B from coumpounds such as DiHEMDA and oleamide which leak into water or DMSO from tubes, tip, and TCware. And that's not even all. Apparently microbicides are added by manufacturers to the plastic along with other chemicals to prevent water from "sticking' to the sides:

" Related slip agents such as erucamide and stearamide are endogenous molecules used routinely in plastic manufacturing (3), whereas quaternary ammonium compounds are included as biocides or antistatic agents. Many such biocides bind substantially to proteins and DNA and have recently been linked with fertility problems in mice (6). Our findings that processing agents leach from laboratory plasticware into biological media and solvents, particularly when liquids are stored in plastic vessels, identify a likely source of error in many assay systems."