Reassembly of wall domains of Roman-snail (Helix pomatia) beta-haemocyanin.

beta-Haemocyanin molecules consist of 20 very large polypeptide chains. These chains are composed of eight structural domains. So-called 'collar' domains can be removed by trypsinolysis of the native cylindrical molecule, resulting in an association of the remaining hollow cylinders into large tubular polymers. Dissociation of the tubular polymers gives one single- and four multi-domain fragments. The role of these fragments in the reassembly process of these tubular polymers was investigated. The two-domain fragment could form tubular polymers. The other domain fragments were not able to form tubular polymers unless in the presence of the two-domain fragment. Tubular polymers with enlarged diameter and ribbon-like structures were observed in the reassembly products when the one-domain fragment was omitted.