The structure and function of immunoglobulin domains: studies with beta-2-microglobulin on the role of the intrachain disulfide bond

摘要: Beta-Microglobulin, a low-molecular-weight protein structurally related to the homology regions of immunoglobulins, has been used study role intrachain disulfide bond in unfolding immunoglobulin domains. The intact could be reversibly unfolded guanidine hydrochloride, as judged by circular dichroism and optical rotation. Similarly, reoxidation reduced protein, during transfer from high concentrations neutral aqueous buffer, yielded product with spectral characteristics typical native protein. However, if free SH groups were prevented reoxidizing either chemical modification or holding them state, molecule appeared randomly coiled state even under conditions where is conformation, on basis chiroptical measurements. complement-fixing activity exhibited beta-2-microglobulin was retained alkylated derivative, suggesting that site may formed linear array amino acids. We suggest model for folding (and domains) which one early events results formation, latter being an obligatory step continued state.