BIOCHEM 2BB3 Lecture Notes - Lecture 5: Adenine, List Of Chairs, Heme
9 Sep 2017
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Protein can be shaped as globular proteins or fibrous networks: collagen, structural (extracellular matrix) protein, help form the cytoskeleton, motor proteins control movement of organelles within the cell. Myoglobin: small; 121/153 aa are found in 8 alpha helices, labelled a h (right picture) Hemoglobin: tetrameric: 2 alpha and 2 beta chains; each subunit (globin) looks like myoglobin. Both: heme found in hydrophobic pocket between e and f helices: his f8 ligands the f(ii) ion, and his e7 that h-bonds with o2. Heme is a prosthetic group (constituent that allows protein to carry out a function) = binds to o2. Mb + o2 mbo2, k = [mb][o2] / [mbo2] Fractional saturation,y: portion of total myoglobin molecules bound to o2 po2, partial pressure of oxygen. As o2 increases, more o2 begins to bind to the same myoglobin until it is saturated p50: oxygen pressure of 50% saturation; when myoglobin"s y half-saturated, and [o2] = k.
