A method is described whereby CD and ORD spectra are computed and plotted from digital data collected simultaneously with the recording of the initial spectrum on a Jasco Model J-20 automatic recording spectroppolarimeter/circular dichrometer.
The procedure eliminates all the customary manual operations in the processing of data, thereby increasing the reliability of the results and saving a substantial amount of time.
The determination of circular dichroism (CD) and optical rotatory dispersion (ORD) spectra is fairly common in studies of the configuration and conformation of optically active compounds. Despite the simplicity of the technique and the availability of automatic recording circular dichrometers/spectropolarimeters, the calculation and plotting of corrected spectra from the recorded traces require much extra time. This is brought about by the need to convert observed ellipticities or rotations to a common (e.g., molar) basis for comparative purposes, as well as the design of older-type instruments which does not provide for the direct processing of data by computer. Under these conditions, time-consuming manual operations for the transformation of recorded CD and ORD spectra into suitable format, are unavoidable. However, the latest models of automatic recording circular dichrometers/spectropolarimeters, such as the Jasco Model 520, can be adapted for the computerized analysis of data. We report here on a procedure developed for the fully automated collection of data and the calculation and plotting of CD and. ORD spectra, in the belief that others may find it useful, too.
MATERIALS
The following materials were purchased from the respective suppliers: D( +) -IO-camphorsulphonic acid monohydrate (Merck pro a&y&), poly-L-glutamic acid (M, + 10,000; Miles-Yeda) , equine myoglobin (3 x recrystallized), and bovine b-chymotrypsin (six times recrystallized; Miles-59