Figure 3.

(A) Size exclusion chromatography profiles of mR1(core) purified with (—) and without (---) addition of 50 µM Zn²⁺. The chromatographic profiles are from a preparative 120 ml Superdex 200 column and monitored by UV absorption. The buffer for mR1(core) purified with added Zn²⁺ contained 50 µM Zn²⁺ and 0.5 M NaCl, while the buffer for mR1(core) purified in the absence of added Zn²⁺ contained 0.5 M NaCl and was treated with Chelex to remove any adventitious metals. (B) SDS-PAGE of mR1(core) purified in the absence of added Zn²⁺. Fractions collected from SEC are A (elution volume 68.2–71.2 mL); B (elution volume 59.2–61.2 mL); and C (elution volume 45.2–48.2 mL). These fractions correspond to lanes A, B, and C on the gel. (C) SDS-PAGE of mR1(core) purified in the presence of Zn²⁺ shows the characteristic dimer band in Fraction B. Fraction B purified in the presence of added Zn²⁺ corresponds to the SEC elution volume collected for Fraction B prepared in the absence of added Zn²⁺.