CHMI-2227EL Lecture 13: CHMI-2227 - Day 13
27 Jun 2018
School
Course
Professor
Biochemistry 2 - Day 13 2018.03.02
Question
-Hemoglobin is
-False: A dimer of subunits with two myoglobin proteins
-False: an erythrocyte
-True: a tetramer of four global chains and one heme prosthetic group
-False: a tetramer of 4 myoglobin proteins
-False: a dimer of subunits each with two distinct protein chains (alpha and beta)
-Which technique is commonly used to determine the 3D conformation of a protein?
-False:Isoelectric focusing
-False: The edman degradation
-False: SDS-page
-True: X-ray crystallography
-One turn of an alpha-helix represent _ amino acid residues
-False: 2.6
-False: 3
-True: 3.6
-False: 4
-False: none of the above
Hemoglobin
Cooperative binding of oxygen to hemoglobin
-O2 binding changes the 3-D conformation of
hemoglobin
-The consequence of this slight change in
conformation is an increase in the affinity of
these other hemoglobin subunits O2
-This phenomenon, where a change in the shape in one subunit trigger similar
changes in other subunits of the same molecule, is called cooperativity
-Molecules exhibiting cooperativity are also called allosteric molecules
-The binding of one oxygen molecule at 1 heme group causes the next oxygen to bind
more strongly, the third oxygen even more strongly and so on
-Allosteric interactions: a change in conformational structure at one location of a
mulitsubunit protein that causes a conformational change at another location on the
protein
-Allosteric interactions occur when an allosteric effector (modulator) binds reversibly to
a protein and modulates its activity
-The binding of an allosteric inhibitor causes the allosteric protein to change from its
active shape (R shape) to its inactive shape (t state)
-The binding of an allosteric activator causes the allosteric protein to change from its
inactive shape (T state) to its active shape (R state)
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Document Summary
False: a dimer of subunits with two myoglobin proteins. True: a tetramer of four global chains and one heme prosthetic group. False: a tetramer of 4 myoglobin proteins. False: a dimer of subunits each with two distinct protein chains (alpha and beta) One turn of an alpha-helix represent _ amino acid residues. O2 binding changes the 3-d conformation of hemoglobin. The consequence of this slight change in conformation is an increase in the af nity of these other hemoglobin subunits o2. This phenomenon, where a change in the shape in one subunit trigger similar changes in other subunits of the same molecule, is called cooperativity. Molecules exhibiting cooperativity are also called allosteric molecules. The binding of one oxygen molecule at 1 heme group causes the next oxygen to bind more strongly, the third oxygen even more strongly and so on.
