Biophysical Analysis

UV/visible Absorbance Spectroscopy

UV absorbance is a reliable method for determining the concentration of protein or DNA in solution. As a method of protein characterization, CBI offers determination of extinction coefficients. The protein concentration is first accurately determined by amino acid analysis, then the absorbance measured by UV spectroscopy on 3 to 5 dilutions of sample. An extinction coefficient is calculated which can then be used to easily and accurately determine the protein concentrations in other solutions of the protein.

Circular Dichroism (CD) Spectroscopy

CD reveals the fractional percent of secondary structural elements within a macromolecule ( -helix, -strand, -turn, unordered elements) and is best used in comparative experiments wherein the effects of a perturbant (on structure) are to be determined. There are two standard types of analysis available, but we can accommodate any other experiments you may wish to design: (1) A single spectrum at one temperature and (2) A wavelength/temperature scan in which CD is monitored while temperature is increased from 10'C - 90'C, and full spectra are taken every 5 degrees.

Fluorescence Spectroscopy

CBI offers fluorescence spectroscopy for a wide variety of purposes ranging from structural analysis of proteins to enzymatic assays employing fluorogenic substrates.

Protein Fluorescence

The intrinsic fluorescence of tryptophan residues provides a built-in probe for structural analysis of proteins. When a tryptophan residue is moved from its microenvironment within a protein and exposed to solvent, its fluorescence is quenched. Thus, when a protein is subjected to changes in temperature, or other factors (e.g. denaturation by urea), the conformational changes can be monitored by a change in fluorescence.

Light Scattering for determination of aggregates

In addition to FPLC SEC, light scattering is the best method for determining the presence of aggregates. Duplicate aliquots of each sample are analyzed for the presence of aggregates.



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Commonwealth Biotechnologies, Inc. 601 Biotech Drive, Richmond, VA 23235 800-735-9224 (800-RELY-CBI) FAX: 804-648-2641 email: [email protected]