Incorporation of Allosteric Effectors of Hemoglobin in Red Blood Cells. Biochemical and Physiological Effects

Abstract

This chapter reviews the biochemical and physiological effects of the incorporation of allosteric effectors of hemoglobin in red blood cells. The amount of O 2 that can be released in a particular organ depends on the critical O 2 partial pressure characteristic for the organ and on the architecture of the microvasculature. This O 2 release capacity is controlled by the microcirculation and molecular parameters of the intracellular Hb. The O 2 release capacity can be enhanced by an increase in the co-operability of the Hb molecule; and/or by right shifting of the entire O 2 -binding curve toward higher O 2 partial pressures. An abnormally high affinity of hemoglobin for oxygen shifts the O 2 -binding curve to the left and the P 50 (O 2 partial pressure at which 50% saturation of hemoglobin occurs) decreases causing a lower oxygen release to the tissues. In human RBC, the right-shift is controlled by several allosteric mechanisms, such as Bohr effect, 2, 3-bis-phosphoglycerate (DPG), and CO 2 -binding.