MP - Mass Photometry

MP - Mass Photometry

Please acknowledge the SIP core facility ( RRID: SCR_018986) in publications, on posters, or in talks if you use any instruments in the SIP core facility. Please include SIP's RRID (RRID: SCR_018986) and the grant numbers for instruments funded through instrumentation grants in your acknowledgements. This is a requirement from the funding agencies and is crucial for future funding. Find example text on theÌýAcknowledgement PageÌýor the individual instrument pages.

Mass Photometry in Biochemistry, Biophysics and Structural Biology

Mass photometry (MP) is a cutting-edge technique that allows for the precise measurement of the mass of single molecules in solution. This innovative method is particularly advantageous because it enables the study of biomolecules in their native state, without the need for ionisation or fragmentation, which are typically required in traditional mass spectrometry.

The fundamental principle behind mass photometry involves the detection of light interference. When a focused beam of light strikes a glass surface, a portion of the light is directly reflected, while another portion is scattered by biomolecules as they adhere to the surface. The interaction between the reflected and scattered light produces an interferometric contrast, which is directly correlated with the molar mass of the scattering biomolecules. This unique approach allows researchers to accurately measure the mass of proteins, nucleic acids, and other biomolecules in solution.

Mass photometry offers valuable insights into the molecular weight and oligomeric states of biological macromolecules and complexes. This makes it an invaluable tool in structural biology, where understanding the assembly and structure of biomolecular complexes is crucial. Additionally, in biochemistry and biophysics, MP can be used to study the behaviour and interactions of biomolecules under various conditions, providing a deeper understanding of their functions and dynamics.

Beyond basic research, mass photometry also holds significant potential in drug discovery. By enabling the detailed analysis of biomolecular interactions and complex formation, MP can for example aid in the identification of potential drug targets. It can help in the optimisation of therapeutic molecules, or facilitate quality control of AVV samples by providing a fast and easy way for the quantification of empty, partially filled, full and overfull AAVs. ÌýOverall, mass photometry is a powerful technique that is rapidly becoming essential in the study of biological systems.

Methods and Instruments

MP results of beta Amylase measured in presence and absence of DTT, showing mainly monomer plus DTT and monomer, dimer and tetramer minus DTT

Key highlights of MP in Biology, Biochemistry, and Biophysics

  • Accurate molecular weight measurementsin solution without the need for labelling or modifying the sample, preserving its native state.
  • Compatible with a wide range of biomolecules, including proteins, RNA, DNA, complexes, vesicles, micelles, adeno-associated viruses (AAVs), and even some polymers.
  • Detailed information on sample heterogeneity, enabling the measurement of masses and the number of molecules in different subpopulations within a sample.
  • Compatible with a broad range of buffers, allowing flexibility in experimental conditions.
  • Effective with low concentrations (100 pM to 100 nM) and small sample volumes (15-20 µL), making it suitable for precious or limited samples.
Mass Photometer
close up of MP sample stage

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Instrument and Accesories

Instrument

TwoMP mass photometer from Refeyn

  • Mass range: 30 kDa – 5 MDa
  • Resolution (FWHM): 25 kDa @ 66 kDa, 60 kDa @ 660 kDa)
  • Mass precision: ± 2%
  • Mass error: ± 5% (single measurement)
  • Concentration range: 100 pM – 100 nM
  • Sensitivity: << 1 ng of protein
  • Wavelength: 488 nm
  • Field of view: 4 x 11 μm (@ 500 Hz) up to 12 x 17 μm (@ 135 Hz)
  • Pixel size: 12 nm

AccessoriesÌý

  • ÌýRefeyn AcquireMP for data acquisition
  • ÌýRefeyn Â鶹ÊÓƵMP for data analysis
  • ÌýSample well cassettes (6 sample wells/cassette)
  • ÌýAlignment tool, tweezers, and magnetic slide holders
  • ÌýLens tissue to clean the instrument objective

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Essential Information for Using SIP's MP

Acknowledgements Protocols Training Scheduling Cost Location
Acknowledgements

Why?

Acknowledgements are essential for ensuring the continued success of the Shared Instruments Pool (SIP). They enable us to secure the necessary funding to sustain and expand the SIP, ensuring that our instruments are in optimal working condition and that the methods we offer are at the forefront of biochemical and biophysical research.

Please include SIP's RRID number (RRID: SCR_018986) in your acknowledgements. This allows funding organisations and potential grant reviewers to easily locate publications supported by SIP, helping to evaluate the impact of SIP on our research community.

If facility staff have provided substantial assistance, please consider acknowledging them. If they contributed significantly to the intellectual aspects or conducted important experiments, co-authorship may also be appropriate.

Example text:

We thank the Shared Instruments Pool (RRID: SCR_018986), Department of Biochemistry, Â鶹ÊÓƵ for the use of the Refeyn TWOMP mass photometer. We also thank [Name and title of the facility member providing significant help] for their invaluable assistance with data collection and evaluation.

Please contact Dr Erbse to obtain additional detailed protocols and arrange an initial project consultation and personalised training sessions. Protocols are available as PDF files on the instrument computer, with printed copies stored alongside the instruments.

Interested users can contact Dr Erbse to discuss planned experiments and arrange training sessions. These sessions will involve the use of actual user samples alongside standards, enabling users to collect preliminary data during the training and receive help from core staff right away if Ìýtroubleshooting or optimisation is needed. Users are welcome to request additional training or support sessions at any time. We are always happy to provide a refresher if it has been a while.

After your training is completed, you will be invited to join the Mass Photometer Google calendar.

Sign Up Rules:Ìý
Up to Friday the week before the planned experiment users can sign up for a maximum of 2 days. In the week of the experiment users can sign up for additional time if available.

  • Initial consultation is free. SIP staff are happy to assist with a short pilot experiment if it can be accommodated within SIP's resources.
  • Regular user groups are expected to buy into SIP with a monthly flat fee according to their SIP usage level. For detailed information, please contact Dr Annette Erbse.
  • Users are required to provide all consumables specific to their experiments, including cover slips and appropriate weight standards.
  • Costs for necessary repairs, services, or replacement parts due to normal wear and tear will be shared among all user groups, based on the time used over the past two years. Please note that assuming the instrument is handled properly, such repairs or replacements are infrequent, and costs may arise after a user’s period of use has ended.
  • Users are responsible for covering the costs of repairs or replacement parts needed due to damage caused by carelessness or neglect.

The MP is located on the third floor of JSCBB in the A-Wing, room A350, on East Campus. Proxcard access is required at all times.