BIOMG 3300 Unit 3 Objectives Questions with Correct Answers.Fe3+ - Correct Answer doesn't allow for reversible binding to O2 Fe2+ when bound to 2 heme groups - Correct Answer can cause the formation of radicals, which are bad for the body Ligand - Correct Answer a molecule reversibly bound by a protein binding site - Correct Answer the place where a ligand binds to a protein complementary in size/charge/shape/hydrophilic/hydrophobic character induced fit - Correct Answer structural adaptation that occurs between ligand and protein substrate - Correct Answer a molecule acted on by an enzyme catalytic/active site - Correct Answer ligand binding site on an enzyme myoglobin - Correct Answer a protein used for oxygen storage in muscle -very high affinity for O2, not sensitive to changes in [O2] -hyperbolic affinity curve -1 subunit, no cooperativity heme group - Correct Answer a prosthetic group bound to a protein that incorporates and sequesters free Fe Pyrrole ring - Correct Answer the actual unit of porphyrin ring (in heme groups) Order of AAs most likely to be in protein interior - Correct Answer 1) hydrophobic AAs 2) charged AAs 3) polar uncharged AAs 1 / 2
Fe has how many coordination points - Correct Answer 6: 4 bound to porphyrin ring, 1 bound to proximal His, 1 is O2 binding site Globin - Correct Answer a family of proteins with similar 2' and 3' structures, used for oxygen storage. Most have 8 alpha helices and have heme nestled between 2 of them with 2 His residues coordinated to it P50 - Correct Answer the PO2 where half of the molecule is bound to O2 (50% protein saturation) proximal His role - Correct Answer Keeps Fe in heme group as Fe2+ by binding to coordination bond distal His role - Correct Answer -increases heme's affinity for O2 by forming an H bond with it/stabilizing it -decreases bound Hb's affinity for CO -guards access to heme pocket, can rotate quickly to allow it in molecular breathing How do Globin prevent Fe oxidation - Correct Answer sequester the Fe deep into the protein, and make sure that the proximal His occupies 6th coordination bond molecular breathing - Correct Answer molecular motions-eg rapid flexing of side chains- in a molecule, needed to allow O2 to enter/leave heme pocket in myoglobin Hemoglobin - Correct Answer a tetramic protein with 2 alpha and 2 beta globin side chains -less O2 affinity than myoglobin, influenced by [O2] -4 subunits, cooperative binding What interactions are in hemoglobin 4' structure? - Correct Answer hydrophobic effect, H bonds, ion pairs/salt bridges between unlike subunits 1' sequence in myoglobin and hemoglobin - Correct Answer not similar 3' structure of hemoglobin 1 subunit to myoglobin - Correct Answer quite similar, same alpha helix naming ocnventions
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