Courtesy of PerkinElmer Life and Analytical Sciences
Boston-based PerkinElmer Life and Analytical Sciences
At the heart of the new imaging system is a CCD camera that offers higher throughput with significantly increased sensitivity and resolution. The camera can scan a dozen large-format (up to 27 cm × 33 cm) gels per hour, more than double the rate possible with the previous model. Offering a slightly wider dynamic range than its forerunner (the ProXPRESS), the ProXPRESS 2D can detect virtually any probe with emission spectra falling in the long-wavelength UV or visible ranges, including SPYRO and cyanine dyes, silver stain, and Coomassie™ Brilliant Blue.
The system supports fluorescence, luminescence, absorbance, and reflection detection. It cannot be used to detect radioactive probes, but Rasmussen notes that the vast majority of PerkinElmer's customers now employ nonradioactive methods for proteomics applications.
The ProXPRESS 2D offers three illumination modes: top, bottom, and an innovative option that allows gels to be illuminated from the edge while still sandwiched between plates. With top illumination, a maximum of 42 image frames are taken across the whole gel with the light concentrated into each individual frame. With edge illumination, light is incident along the long dimension and is transmitted through the entire gel; the waveguide effect of the gel plates traps the light in the gel. Developed for applications such as multicolor differential protein analyses, edge illumination enables more efficient use of total light and thereby reduces background levels, improving sensitivity.
The ProXPRESS 2D employs PerkinElmer's software packages for automated spot acquisition (ProSCAN) and image analysis and quantification (ProFINDER 2D), and is designed to complement other offerings of PerkinElmer's proteomics product suite, including its ProXCISION™ gel-cutting robot and prOTOF™ 2000 MALDI mass spectrometer, says Rasmussen.
Douglas Lamont, facility manager of the FingerPrints Proteomics Facility, University of Dundee, Scotland, who beta-tested the ProXPRESS 2D, calls the instrument a "significant improvement over its predecessor." Says Lamont, "We've obtained good results for a wide variety of stains tested."
- Deborah Fitzgerald