The exfoliated single-layer titanate can rapidly restack and reversibly release heme protein simply by adjustment of the pH value. The composites have regularly layered structure and powdery morphology by their ideal layer-to-layer assembly, which provides the titanate nanosheet an unusual specific intercalation capacity of 5900 mg g(-1) for the protein. The bound and released proteins keep active relative to the intact protein. The hemoglobin thermal and organic solvent stabilities are improved by the protective environment of the titanate host.