Three notable references to the use of MULTAN for the solution of the partial structure
are by Navia *et al* [87] and Wilson [118] where the isomorphous differences between
native and derivative
structures were utilised, and Mukherjee *et al* [86] where
Bijvoet differences were used. In the latter reference, heavy atom positions
were determined for three structures: Cytochrome- containing two iron atoms per asymmetric unit,
Pea Lectin with two manganese atoms in the asymmetric unit and a mercury derivative of -amylase
with one mercury atom per asymmetric unit. In these cases Bijvoet differences were used for the calculation
of normalised structure factors.

In each of the cases studied, the phase set with the highest combined figure of merit corresponded to the correct solution when compared with MIR results. For two of the structures however the heavy atom positions were displaced by 2.5 Å and 5.0 Å away from the refined MIR positions.

Mukherjee *et al* showed that the largest Bijvoet differences measured provide a reasonable estimate
of the magnitude of the imaginary part of the heavy atom structure factor, since (from Eq. )

and for the largest 's where and are orthogonal we see that

This is convenient since MULTAN uses a set of largest normalised structure factors, 's, in the calculation of triple product relations. Thus the measured may be used directly as input to MULTAN in a manner similar to using for a small molecule.

Fri Oct 7 15:42:16 MET 1994