Displaying inter-main chain hydrogen bond patterns in proteins.
Two computer graphics techniques for displaying hydrogen bonds between the main chains of different proteins are described, and illustrated for two thiol proteases. (The X-ray crystallography was performed by Kamphuis et al. in 1984, and by Baker and Dodson in 1980.) One is a three-dimensional model that can be manipulated in space; the hydrogen bonds are represented with the smoothed alpha-carbon plot of the polypeptide chain. In the other type of display, hydrogen bonds are viewed in relation to the one-dimensional sequence. Both types of picture facilitate visualization of hydrogen bond patterns, such that loop motifs, as well as alpha-helices and beta-sheets, can be examined easily. We suggest that such displays are useful as a general means of displaying whole proteins and whole domains because they reveal more information than do conventional simplified pictures of proteins, which focus exclusively on alpha-helices and beta-sheets. These techniques can be implemented on a UNIX-based computer graphics workstation. (UNIX is a trademark of Bell Telephone laboratories.)