Far-UV CD is usually used to measure protein secondary structure percentages (alpha-helix, beta-sheet, random coil). Near-UV CD looks at conformational changes in a protein by monitoring their effect on the CD spectrum of, predominantly, tryptophan residues.

Some papers and links are attached..study and inform me

Circular dichroism (CD) is dichroism involving circularly polarized light, i.e., the differential absorption of left- and right-handed light.[1][2] Left-hand circular (LHC) and right-hand circular (RHC) polarized light represent two possible spin angular momentum states for a photon, and so circular dichroism is also referred to as dichroism for spin angular momentum.[3] This phenomenon was discovered by Jean-Baptiste Biot, Augustin Fresnel, and Aimé Cotton in the first half of the 19th century.[4] It is exhibited in the absorption bands of optically active chiral molecules. CD spectroscopy has a wide range of applications in many different fields. Most notably, UV CD is used to investigate the secondary structure of proteins.[5] UV/Vis CD is used to investigate charge-transfer transitions.[6] Near-infrared CD is used to investigate geometric and electronic structure by probing metal d→d transitions.[2] Vibrational circular dichroism, which uses light from the infrared energy region, is used for structural studies of small organic molecules, and most recently proteins and DNA.[5]

see Wikipedia...

http://ctrstbio.org.uic.edu/manuals/kelly.pdf

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2728378/

Far-UV CD is usually used to measure protein secondary structure percentages (alpha-helix, beta-sheet, random coil). Near-UV CD looks at conformational changes in a protein by monitoring their effect on the CD spectrum of, predominantly, tryptophan residues.

Thank you Dr. Shapiro. Your answer is really helpful.

As some colleagues already said, Far UV is used to analyse protein conformation, to determine whether it is beta sheet or alpha helix. The absorbance for Far UV is predominantley 200 -250 nm. on the other hand, near UV is used to study protein aggregation in extreme conditions, at the moment i am testing antibody thermal unfolding.