Near UV-CD spectra of monomeric RNase A and its oligomeric aggregates. Each protein species was dissolved in 0.1 M sodium phosphate buffer, pH 6.7. Details are given in the Materials and Methods section. (—) monomer, M; (• • • •) minor dimer, D1; (- - - -) major dimer, D2; (-•-•-) less basic trimer, T1; (– –) more basic trimer, T2; (– - – -) less basic tetramer, TT1; (-••-••-) more basic tetramer, TT2.