Miniaturized two-dimensional gel electrophoresis of high-molecular-weight proteins using low-concentration multifilament-supporting gel for isoelectric focusing

A miniaturized two-dimensional gel electrophoresis (2-DE) system was constructed with a multifilament-supporting (MFS) gel as a first-dimensional gel for isoelectric focusing (IEF). The MFS gel was 1 mm in diameter, had a multifilament yarn of acrylic as a gel-support, and could provide low-concentration (2.5%T) polyacrylamide with sufficient mechanical strength, resulting in fast IEF, and clear 2-D spots due to the relatively large pore and improved transfer efficiency from the first-dimensional gel to the second-dimensional one of especially high-molecular-weight (HMW) proteins. In this study, by using the MFS gel of 4 cm in length as a miniaturized IEF gel, three colored proteins were separated in 8 min, which was about twice faster than using the MFS gel of standard length (7 cm). The second-dimensional gel was also miniaturized to be 55 mm wide, 40 mm long and 0.75 mm thick. The low-concentration MFS gel after IEF was easily transferred onto the top of the miniaturized second-dimensional gel with a tweezers. By using the miniaturized 2-DE system, the HMW size marker was separated in 30 min by IEF and in 25 min by native-polyacrylamide gel electrophoresis (Native-PAGE), which was at least twice faster than by using the standard size 2-DE system using MFS gel. This miniaturized 2-DE system could be expected as a useful separation method for fast protein diagnosis and screening.