The rearrangement of the T-form of hemoglobin to the R-form (Select ALL that apply) increases the ioniclelectrostatic interactions of the amino acid residues between subunits in the T . state. requires the binding of at least three oxygen molecules. occurs when oxygen binds to any of its heme cofactors. involves the movement of the Fe (II) into the heme plane. opens a central cavity for easy BPG binding..