CHEM 440
Biochemistry I
J. D. Cronk   Syllabus [ Previous | Next ] Pick a lecture:
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Lecture 15. Oxygen binding proteins: Myoglobin and hemoglobin

Monday 10 October 2011

Myoglobin, a monomeric oxygen-binding protein. Oxygen coordinates to Fe2+ located at the center of a heme prosthetic group. Myoglobin displays a hyperbolic oygen binding curve. The efficiency of oxygen pickup and delivery can be much improved with a sigmoidal oxygen binding profile, the result of positive cooperativity among subunits of a multimeric oxygen-binding protein such as hemoglobin. The two-state ("R" and "T") concept and a model for positive cooperativity. Structural effects of oxygen binding on tertiary and quaternary structure.

Reading: VVP3e - Ch.7, pp.176-186.
15. Summary

Lecture 15 Summary

Text highlights: Oxygen binding to myoglobin and hemoglobin. Myoglobin is a monomeric oxygen-binding protein containing a heme prosthetic group. Myoglobin, whose physiological role is to facilitate diffusion in muscle, has a hyperbolic oxygen binding curve. The equation for this curve is readily derived from the expression for the oxygen-binding equilibrium and the definition for fractional saturation. Hemoglobin is a tetramer with two conformations. Other oxygen-transport proteins (box). Max Perutz and the structure and function of hemoglobin (box). Oxygen binds cooperatively to hemoglobin. The Hill equation describes hemoglobin's oxygen binding curve. Hemoglobin's two conformations have different affinities for oxygen. The lower affinity conformation, denoted the T state, can undergo a change to the higher affinity R state, a conformational switch triggered by oxygen binding. The molecular details of this switch are discussed.
 

 

Learning objectives

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Page update in progress 10-12-2011

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[ E-mail: cronk@gonzaga.edu ]