IMAGE SEEKING FUNCTIONS ANALYSIS IN PROTEIN CRYSTALLOGRAPHY

The problem of detecting a known weighted vector set in a Patterson ma p can be automatically solved using Image Seeking Functions (ISF). The ''weighted minimum-average function'' is the basis of the vector spac e orientation search (for small molecules) successfully used by the pr ogram ORIENT, included in the DIRDIF system. Recently, due to the incr easing importance of ''vector methods'' in protein crystallography. we have undertaken the modification of the program ORIENT in order to de velop a useful rotation function for protein crystallography. It is ne cessary to carefully study the ISF's behaviour before using them with macromolecular data. Numerical simulations (based on computer generate d random numbers) have been performed in order to choose the most appr opiate ISF for this new field, concluding that the use of the ''weight ed minimum-average function'' with macromolecular data is risky, and m ore promising ISF can be investigated.