BIOCHEM 3G03 Chapter Notes - Chapter 5: Fetal Hemoglobin, Tetrameric Protein, Globular Protein
10 Oct 2016
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Motor proteins: facilitate movement of cells/organelles along tracts of cytoskeletal fibers. Wedged into a hydrophobic pocket between helices. 4 ligands by n atoms of porphyrin ring system 5th ligand by his residue of myoglobin (his f8), 6th reversibly by molecular oxygen oxygen carrier function. Fe(ii) by itself is easily oxidized to fe(iii) which cannot bind o2 does(cid:374)"t happe(cid:374) (cid:449)he(cid:374) it"s part of a protein. Hemoglobin: protein in red blood cells that transports o2: tetrameric each subunits resemble myoglobin. Both globular proteins, unlike most abundant proteins that are fibrous elongated and may form extended structures (collagen makes up cytoskeleton) Oxygen binding to myoglobin depends on oxygen concentration. Myoglobin most likely just facilitates oxygen diffusion through muscle cells/binds other small molecules such as nitric oxide not for storage. K is the dissociation constant; reciprocal of association constant (ka) Proportion of total # myoglobin that have bound o2 = fractional saturation (y)
