Hemoglobin is the most important respiratory protein of vertebrates by virtue of its ability to transport oxygen from the lungs to body tissues, and to facilitate the return transport of carbon dioxide. It is used as a coloring agent for pet foods, a natural source of iron for nutraceuticals, a protein source for non-ruminant animals, and as a raw material for pharmaceutical porphyrin derivative production.
Nobuo Ul. Isoelectric points and conformation of proteins: I. Effect of urea on the behavior of some proteins in isoelectric focusing. Biochimica et Biophysica Acta (BBA) - Protein Structure. 1971, 229 (3),567-581 .