Arthur M. Lesk

Arthur M. Lesk, is a researcher and author, predominantly in the field of biochemistry and molecular biology.

Along with Karl D. Hardman, Lesk wrote the first computer program for generating the schematic diagram of protein structure. It is known to produce one of the most effective representations of the protein structures and employs the classification scheme for Ribbon Diagrams created by Jane Richardson. Although these schematic diagrams are less detailed compared to the other representations, such as, picture stimulating wire models or space-filling models, it is more effective in presenting the topological relationships among elements of secondary structure and protein, due to its simplistic structural expression. This was then further improved by creating a program to produce stereoscopic pairs of diagrams. As a result, the viewer’s ability to perceive spatial relationship in complex molecules was enhanced.

Operation of the program
The basic operation of the program begins with the execution of line drawing. There are four phases involved in this program:


 * 1) The input phase – Program reads the input files. There are two input files. They are the coordinates and the details of the contents and appearance of the picture.
 * 2) Picture generation – Geometric transformation of coordinates are generated by the program into picture elements. For example, a cylinder of appropriate size and orientation about the z-axis represents α-helix; each peptide plane is determined for Ribbon Diagrams and β-sheets; and spline fit is used for curved sheets.
 * 3) Hidden-line removal – This step is only required by the cylinders of α-helices and the arrows of β-sheets, not skeletal models. Picture of these structures are classified by three levels of “optical density” – transparent, translucent, or opaque. If lines are passing behind the transparent object, it is not changed. If it passes behind a translucent object, it is altered into dashed lines. If it is opaque, the lines passing through the object are removed completely. This step can be replaced with an alternative step to create a Colour-Raster     Output. The lines are ignored and the windows are painted according to the user.
 * 4) Output – Character strings are extended to sets of line segments through a set of stroke tables. Line segments are placed into the two dimensional space.