Bacterial protein serves as sensor
A German-French team led by Prof. Dr. Jan C. Behrends and Dr. Gerhard Baaken from the University of Freiburg and Dr. Abdelghani Oukhaled from the Universities of Evry and Cergy-Pontoise has developed a method capable of precisely measuring the size of individual molecules. To do so, the researchers used the protein aerolysin from the bacterium Aeromonas hydrophila instead of the protein previously used for this purpose, alpha-hemolysin from the bacterium Staphylococcus aureus. The method remains unchanged: The protein forms a pore in an artificial cell membrane. The researchers insert the molecule whose size they wish to measure into this pore by guiding an ionic current through it. The molecule partially blocks this current - similar to the way an object illuminated by a spotlight throws a shadow. The rest of the ionic current, which makes it through the pore, can then be used to measure the molecule. "The new pore...