mass photometer

• Subject Area: Plant Sciences
• Term: Funded in 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 555723355

This application is to co-finance the purchase of a mass photometer that allows rapid testing of protein isolates in solution to support the research program of Prof. Hans-Henning Kunz, the recently appointed Chair of Plant Biochemistry and Physiology, and other groups at LMU biology e.g., Profs. Leister, Jung, Nickelsen, Osman, Robatzek, Cordes. The advent of the mass photometer has allowed the direct molecular characterization of proteins, protein complexes, and protein dynamics simply through the use of light scattering. Currently, the LMU department of biology (44 faculty + 300 researchers) does not own a mass photometer. We will employ our established management infrastructure i.e., the Bioanalytics core facility, to optimize equipment usage, data acquisition, data storage, analyses, and most importantly user training and support of mass photometry operators of all experience levels. To address current and new questions in biology the use of single-particle cryo-electron microscopy (cryo-EM) has become indispensable. Here, mass photometry presents a highly cost-effective way to evaluate the sample quality (homogeneity, size distribution, etc.) and integrity before moving on with pricy and laborious investigations, which often require off- campus travels. The first mass photometer at LMU biology is critical for the applicants’ future research programs, the DFG-funded Collaborative Research Centre TRR175 – “The Green Hub”, and several other DFG, ERC, and BMBF-funded projects in our unit. Through extensive test experiments, presented in this proposal, we have specified a 488 nm laser-based mass photometer system to enable label-free mass detection and complex formation of biomolecules and nanostructures ranging from 30 kDa to 5 MDa with several features that guarantee cutting edge molecule analysis. The main applications of the machine will be a) the mass detection of isolated protein and transport protein complexes with and without detergents, b) the study of real-time protein- protein, protein-DNA, and protein-RNA complex formation, and c) the characterization of nanostructures, DNA-, RNA-molecules, d) and extracellular vesicles. Unlike other methods, mass photometry does not indirectly derive molecular mass from the hydrodynamic radius but directly correlates mass with the light scattered by a single particle. This is a unique way to differentiate between particles of similar size but different mass.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Massenphotometer
• Instrumentation Group: 5360 Meßgeräte für gestreutes und reflektiertes Licht, optische Oberflächen-Prüfgeräte
• Applicant Institution: Ludwig-Maximilians-Universität München
• Leader: Professor Dr. Hans-Henning Kunz