A dispersive vibrational circular dichroism (VCD) instrument has been designed and optimized for the measurement of mid-infrared (MIR) bands such as the amide I and amide II vibrational modes of peptides and proteins. The major design considerations were to construct a compact VCD instrument for biological molecules, to increase signal-to-noise (S/N) ratio, to simultaneously collect and digitize the sample transmission and polarization modulation signals, and to digitally ratio them to yield a VCD spectrum. These were realized by assembling new components using design factors adapted from previous VCD instruments. A collection of spectra for peptides and proteins having different dominant secondary structures (alpha-helix, beta-sheet, and random coil) measured for identical samples under the same conditions showed that the new instrument had substantially improved S/N as compared with our previous dispersive VCD instrument. These instruments both provide protein VCD for the amide I that are comparable to or somewhat better than those measurable with commercial Fourier transform (FT) VCD instruments if just the amide I band in the spectra is obtained at modest resolution (8 cm<sup>−1</sup>) with the same total data collection time on each type of instrument.
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.
Contact your librarian or system administrator
Login to access OSA Member Subscription