1AJ9:
reference: Human carboxyhemoglobin at 2.2 A resolution: structure and solvent comparisons of R-state, R2-state and T-state hemoglobins., Vasquez GB, Ji X, Fronticelli C, Gilliland GL, Acta Crystallogr D Biol Crystallogr 1998 May 1;54 ( Pt 3):355-66. PMID: 9761903

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