BIOC 3560 Lecture 3: biochem PACK THREE.pdf
3 Dec 2014
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Myoglobin (mb: single polypeptide, 153 a. a. residues, 16. 7 kda, 8 -helices, 78% of amino acids are found in helices. Binding depends on: conformation of the ligand-binding site, molecular flexibility of the protein. Breathing: small, rapid molecular motions within a protein. The conjugated double bond system of heme causes absorption of visible light. Binding of o2 affects the distribution of electrons in heme and differentially alters the absorption of different wavelengths of light by heme. This then affects the apparent colour of globins. Reversible protein-ligand interaction binding sites occupied total binding sites. From this, and using terms from the previous slide, an equation for protein- ligand binding can be derived. Because oxygen is a gas, the equation for o2-binding substitutes terms for partial pressure po2 po2 + p50 equation 5-11. Curve for myoglobin binding o2 po2 po2 po2 + p50 po2 + p50.
