Circular dichroism (CD) spectroscopy is an important tool for characterizing the conformation (secondary structure and tertiary structure) and thermal stability of proteins and DNA. It is often used in comparability protocols to demonstrate similarity of molecular conformation.

Alliance Protein Laboratories has been offering circular dichroism spectroscopy services since 1998 and has completed hundreds of CD analysis projects on proteins, peptides, nucleic acids, and other molecules. At A.P.L. all the CD experiments and interpretation are done by Tsutomu Arakawa, a recognized expert with over 25 years experience in biotech product development and over 80 publications involving CD measurements.

Further background on CD and its applications can be found here.

A.P.L. has a Jasco J-715 spectropolarimeter (picture) equipped with Peltier temperature control for thermal unfolding studies. Turn-around for CD studies is generally 2 weeks or less.

Before even considering using another company for CD analysis see questions you need to ask a biophysical lab.

Below are listed downloadable versions of two of our presentations involving use of circular dichroism in comparability protocols and a publication illustrating our unique thermal unfolding analysis software:

"Measuring Comparability of Conformation, Heterogeneity, and Aggregation with Circular Dichroism and Analytical Ultracentrifugation", invited talk, State of the Art Methods for the Characterization of Biological Products and Assessment of Comparability, NIH, June 2003

"Challenges in measuring comparability of aggregation and conformation for biosimilars (and often innovator products too!)", poster, WCBP 2009

"Kinetic and Thermodynamic Analysis of Thermal Unfolding of Recombinant Erythropoietin", Biosci. Biotechnol. Biochem. 65, 121-1327, 2001