where tr is the retention time and

where tr is the retention time and wb is the wide time
of the peak. Results showed that the NTP at the
large scale chromatography was higher than at the
small scale chromatography for both proteins
(Table 3). In both cases the same particles and
conditions were used, the only difference is the
column diameter to particle size ratio. This ratio
was 250 for the small scale chromatography
whereas it was 900 for the large scale. In both cases,
the values were high enough to ensure high packing
quality. The higher efficiency of the large scale
versus the small scale is, likely, due to the reduction
of the extra-column band spreading at large scale.
When a chromatographic process is scaled the ratio
between extra-column to column band spreading
decrease. This implies that if the effective performance
of the column remained constant the total
performance at larger scale is higher.
Regarding the purity of the fractions, SDSPAGE
shows that fraction II yields three bands
corresponding to B-PE subunits (Fig. 6a). The

-subunit contains 164 amino-acid residues and a
calculated molecular mass (including the two PEB
chromophores) of 18 991 Da, therefore, its mobility
is larger than that of the -subunit that contains 177
residues and has a molecular mass of 20 315 Da
including 3 PEB (Sidler et al., 1989), both are
present in similar amounts. The third band corresponds
to the -subunit, a minor component of
apparent molecular mass of about 27 000 Da (Ficner
et al., 1992; Koller and Wehrmeyer, 1975;
Redlinger and Gantt, 1981). By comparison with
standards, we obtained molecular mass of the
, 
and -subunits of about 16 500, 18 000 and 27 000
Da, respectively. These values are in agreement
with the previously reported values estimated by
SDS-PAGE (Ficner et al., 1992; Koller and