Ethoxyformylation of Helix pomatia haemocyanin.

摘要: Ethoxyformylation of Helix pomatia haemocyanin was studied to investigate the role histidine residues in binding copper and dissociation properties protein. At neutral pH ethoxyformylation gives rise a difference spectrum with maximum at 240 nm, characteristic ethoxyformylimidazole. Initial-rate studies 250 nm reveal reaction be bimolecular. The rate constant depends on follows titration residues. complete time course is complicated by hydrolysis reagent products. Ethoxyformylation α-haemocyanin 6.0 causes protein dissociate into halves, 6.5 higher proceeds tenths. β-Haemocyanin does not 6.0, values it dissociates completely An induction period seen reaction, indicating that certain number groups have modified before starts. This lowered raising pH. The ethoxyformylimidazole can enhanced NH2OH · HCl. During halves reassociate quantitatively wholes, tenths large aggregates. Modification 7.0 above destroys site high concentration. apoprotein prevents reconstitution. In both cases linear relationship found between band content. Parallel liberation copper, tyrosine become accessible, as shown negative 278 upon or spectrophotometric titrations.