Hemoglobin: molecular changes during anuran metamorphosis.

Anuran metamorphosis is accompanied by changes in the sedimentation patterns of the lysates of red blood cells of several species. Rana grylio and Rana catesbeiana tadpoles have hemoglobins that sediment at 4.3S (molecular weight, 68,000) and gradually produce a heavier 7.0S component (estimated molecular weight, 136,000) during metamorphosis to the adult frog. There is extensive change in the amino acid compositions of these hemoglobins; these changes may account for observed changes in electrophoretic mobility.