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Chapter 15: Problem 15

Lactate, a metabolite produced under anaerobic conditions in mus cle, lowers the affinity of myoglobin for \(\mathrm{O}_{2}\). This effect is beneficial, because \(\mathrm{O}_{2}\) dissociation from Mb under anaerobic conditions will provide the muscle with oxygen. Lactate binds to Mb at a site dis tinct from the O \(_{2}\) -binding site at the heme. In light of this observation, discuss whether myoglobin should be considered an allosteric protein.

Short Answer

Expert verified
Yes, myoglobin should be considered an allosteric protein as lactate binding modifies its structure and changes its function, which is the main characteristic of allosteric proteins.

Step by step solution

01

Understand the concept of Allosteric Proteins

Allosteric proteins are those proteins in which binding of a molecule (effectors) at a site other than the active site triggers a conformational change in its structure affecting its function, often resulting in enhanced or decreased activity.
02

Analyze the Role of Lactate in Myoglobin

Lactate decreases the affinity of myoglobin for \(O_{2}\) by binding at a site different than the oxygen-binding site. This triggers changes in the structure that affect the protein's function causing the oxygen to dissociate from myoglobin.
03

Compare with Allosteric Protein Characteristics

Since the definition of allosteric proteins and the behavior of myoglobin when it interacts with lactate coincide (A secondary molecule, lactate, causing a conformational change that alters its function), it can be said that myoglobin behaves as an allosteric protein in this context.

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Most popular questions from this chapter

Figure 15.17 traces the activation of glycogen phosphorylase from hormone to phosphorylation of the \(b\) form of glycogen phosphorylase to the \(a\) form. These effects are reversible when hormone disappears. Suggest reactions by which such reversibility is achieved.

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