Mass Spectrometry-Based Protein Detection Technique Speeds Optimization of Biofuel Protein Levels in Metabolically Engineered Microbes

The Science

Joint BioEnergy Institute researchers have developed a mass spectrometry-based protein detection technique called multiple-reaction monitoring (MRM) for identifying microbial proteins that can convert cellulosic sugars into biofuels. With the MRM technique, researchers can detect multiple target proteins in the complex protein mixtures of native cells and rapidly change the specific proteins to be targeted, something not possible with conventional protein detection technology. When coupled to liquid chromatography, MRM analysis offers high selectivity and sensitivity. It eliminates background signal and noise even in the most complex protein mixtures by utilizing two targeted points – a peptide mass and a specific fragment mass generated by mass spectrometry. Since the entire mass range is not scanned and only combinations of peptide and fragment masses are monitored, MRM can be used to detect and quantify up to 10 different proteins in a single liquid chromatography separation.


The MRM technique is a valuable tool for analyzing enzyme complexes in a variety of JBEI projects such as the synthetic protein scaffold work reported in Dueber, J. E., G. C. Wu, G. R. Malmirchegini, T. S. Moon, C. J. Petzold, A. V. Ullal, K. L. Prather, J. D. Keasling. 2009. “Synthetic Protein Scaffolds Provide Modular Control over Metabolic Flux,” Nature Biotechnology 27(8), 753-59. DOI:10.1038/nbt.1557.