Carbon Dioxide and the Amino Group

The subsequent reaction indicates the combination between CO₂ and the amino group on protein, including haemoglobin.

In plasma the protein concentration is about 7%. However, in the RBCs, haemoglobin – the principal erythrocyte protein – constitutes about 30% of the contents, so a greater amount is proportionately transported intracellularly as haemoglobinic acid. The amount of CO₂ bound as carbamate to Hb in erythrocytes or to plasma proteins depends on Hb O₂ saturation, 2,3-diphosphoglycerate (2,3-DPG) concentration in the case of RBCs, and on [H⁺] in the case of both RBCs and plasma.