Corrigendum

Abstract

1.1. The haemocyanin of left-handed whelk Busycon contrarium (Conrad) exists largely as six or more multi-decameric aggregates characterized by sedimentation coefficients of approximately 105S, 1032S, 155S, 170S, 185S and about 200–220S.2.2. These aggregtes represent di-to hepta- or octa-decameric assemblies of the basic haemocyanin decamer having a mol. wt of 4.3 × 106–4.5 × 106.3.3. The fully dissociated subunits in 8.0 M urea (pH 8.5) and at pH 11.1, 0.01 M EDTA† have mol. wts of 4.78 × 105 and 4.62 × 105, close to one-tenth of the mol. wt of the basic decameric unit of most gastropod haemocyanins.4.4. The pH dependence of the mol. wts (Mw), studied by light-scattering at the constant protein concentration of 0.010%, exhibit bell-shaped pH transition profiles with mol. wt values of about 16 × 106 in the presence of 0.01 M Mg2+, in the pH region from about pH 4.5–8.0; in the absence of stabilizing divalent ions the observed mol. wt is about 10 × 106 at pH 4.5–7.0. Below pH 4.5 and above 7.0–8.0 there is a sharp drop in mol. wt. to about 4 × 105–4.5 × 105.5.5. The transition profiles observed with both the urea and salt series of probes investigated at concentration = 0.010% are found to produce aggregation at low reagent concentrations with mol. wt changes from about 9 × 106–12 × 106–14 × 106, followed by a decrease in mol. wt. below 4.3 × 106–4.5 × 106 of the haemocyanin decamers. The initial process suggests assocition of B. contrarium haemocyanin to higher multi-decameric forms through stabilization of the polar and ionic contacts between the decamers.6.6. Hydrophobic stabilization of the subunits within each decamer is suggested by the dissociation of the subunits at higher reagent concentrations and the changes in effectiveness of the ureas as dissociating agents, which correlate with their hydrophobicity and hydrocarbon content.