title: Structural and functional aspects of collar domains of Helix pomatia beta c-hemocyanin.
abstract: Digestion of beta c-hemocyanin yielded tubular polymers as well as so-called collars. Analysis of the collar fraction revealed that it consisted of two fragments, one having a relative molecular mass of approx. 125000 and the other a relative molecular mass of approx. 65000. They were separated using ion-exchange chromatography. The large fragment dissociated around pH 9.5 into two components having a molecular mass of approx. 65000. Both fragments bound oxygen and displayed heterotropic interactions. The large fragment bound oxygen with a Hill coefficient less than unity under certain conditions. The fragments differed also in amino acid composition, sugar content, spectral parameters, association-dissociation phenomena and ageing. by comparison with fragments obtained after limited proteolysis of tenth molecules, their location in the polypeptide chain was established.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002852:Chromatography, Ion Exchange; D006372:Helix, Snails / Q000032:analysis*; D006433:Hemocyanins / Q000032:analysis*; D008970:Molecular Weight; D010100:Oxygen; D010455:Peptides / Q000302:isolation & purification*; D013053:Spectrophotometry
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D010455:Peptides; D006433:Hemocyanins; D010100:Oxygen