Grasp General Description

Grasp was developed by Anthony Nicholls at Columbia University to visualize electrostatic potentials at the surface of macromolecules. It evolved to enable the general mapping of atomic properties to the surface contour. Subsets of atoms, surfaces, properties, etc. may be defined and diplayed differentially. Simple math is availble to manipulate the values of maps projected on the surface of macromolecules.

It is excellent for calculating and displaying surface properties, including internal cavity surfaces. The program also creates cpk, ball and stick, ribbons and tube models of macromolecules.

The User Manual is available online or as hard copy in the core.

There is also a Home Page for Grasp.

An improved collection of colors for GRASP can be used by copying this file:

/eve/www/csb_home/userguides/graphics/grasp/defcol.dat

to your current workng directory.

You can display these colors by typing:

ipaste /eve/www/csb_home/userguides/graphics/grasp/colors25.rgb

To Get Started

First type:

setup grasp (or source /sgi/local/bin/grasp.set)

Then type:

cp /sgi/local/grasp/examples/6lyz* .

Then type:

grasp

Once you have opened grasp click the right mouse button to get the main menu.

Choose: READ | PDB File | Show list | 6lyz.pdb

Click the right mouse button again to get the main menu and choose:

READ | History/Script (+execute) | 6lyz-lysozyme.his

You are now in a tutorial script. Enlarge the UNIX shell and read the comments as you step through the tutorial by clicking on the appropriate prompt.

(To see what commands are being given to the program you could open another window and read through the "6lyz-lysozyme.his" file as you go.)

A script describes exactly what you do in the GRASP window and can be run by reading it into a GRASP session. An example of a minimalist GRASP script is available.

Please Note: If you publish a figure using this program please cite the following:

Nicholls, A., Sharp, K.A. and Honig, B. Proteins (1991) 11,281-296

Nicholls, A., Bharadwaj, R. and Honig, B. Biophys J. (1993) 64, Part 2, A166