Skip Navigation


Doug Barrick
Professor, Biophysics


Vincent J. Hilser
Professor, Biology


Katherine Tripp, Ph.D.
Center Manager

Johns Hopkins University
3400 N. Charles Street
Baltimore, MD 21218
(410) 516-3598 office
(410) 516-4118 fax

CMB Instrumentation


Analytical Ultracentrifuge (AUC)


Image of Beckman AUC


AUC is the method of choice for determination of the molecular weight of macromolecular complexes (from small polypeptides to viruses) under native solution conditions.  The radial distribution of protein in the spinning cell, that arises from the action of both the outward centrifugal force and random diffusion, is mass and shape dependent (in a sedimentation velocity experiment).  Analysis of data can determine even very weak association constants and reveal the size distributions of solutions containing multiple species.

Our Beckman XL-I has absorption as well as interference optics able to observe sedimenting species under a wide range of buffer conditions and concentrations.


Differential Scanning Calorimeter (DSC)


Differential Scanning Calorimetry (DSC) measures enthalpy (ΔH) of unfolding due to heat denaturation.  DSC is also used to determine the change in heat capacity.  DSC can elucidate the factors that contribute to the folding and stability of native biomolecules, including hydrophobic interactions, hydrogen bonding, conformational entropy, and the physical environment.

The center currently has two Microcal DSCs available for user use.


Isothermal Titration Calorimeter (ITC)

  Isothermal Titration Calorimetry (ITC) is a technique that directly measures the heat released or absorbed during a biomolecular binding event.  Measurement of this heat enables accurate determination of binding constants, reaction stoichiometry, enthalpy and entropy, thereby providing complete information of the molecular interaction in a single experiment.  ITC is the method of choice for characterizing biomolecular interactions. 

Circular Dichorism (CD)



Circular dichroism (CD) is the property of chiral molecules to absorb the right and left components of circularly polarised light to a different extent.  CD spectroscopy measures this differential absorbance.  Nearly all biological macromolecules are chiral and lend themselves to CD experiments.  The Aviv Circular Dichroism Spectrometer records CD as a function of wavelength, time and temperature.

The center currently has two Aviv CDs available for user use.



Fluorescence Spectrometer

  Intrinsic fluorescence or site-specific labels can be used to monitor oligomerization, ligand binding, folding and local conformational rearrangements.  Fluorescence resonance energy transfer between suitable pairs of fluorophores gives information on their distance. Excitation and emission polarisers allow for anisotropy measurements.



© The Johns Hopkins University. All rights reserved.