Myoglobin's a single-chain globular protein of 153 amino acids, containing a heme (iron-containing porphyrin) prosthetic group in the center around which the remaining apoprotein folds. It's eight alpha helices and a hydrophobic core. It's a molecular weight of 16,700 daltons, and's the primary oxygen-carrying pigment of muscle tissues. Unlike the blood-borne hemoglobin, to which it's structurally related, this protein doesn't exhibit cooperative binding of oxygen, since positive cooperativity's… (More on Myoglobin)