Catalytic Strategies 2

Why is CO₂ removal important in the body?

CO₂ must be removed from the body and replaced with O₂.

How is CO₂ transported in the blood?

Converted into carbonic acid (H₂CO₃) and bicarbonate (HCO₃⁻) for transport.

What is the role of carbonic anhydrase in CO₂ transport?

Carbonic anhydrase converts bicarbonate back to CO₂ for exhalation in the lungs.

What is the effect of raising pH on CO₂ hydration kinetics?

Raising pH would speed up the reaction, but it's not safe in blood.

What does the enzyme carbonic anhydrase do?

It catalyzes the conversion of CO₂ and water to bicarbonate.

What percentage of CO₂ is converted to bicarbonate by carbonic anhydrase?

70% of CO₂ is converted to bicarbonate.

What ions are essential for the active site of carbonic anhydrase?

Zinc ions (Zn²⁺) are essential for the active site of carbonic anhydrase.

What is the mechanism of how carbonic anhydrase catalyzes the formation of bicarbonate?

It involves Zn²⁺ reducing water's pKa, CO₂ binding, and OH⁻ attacking CO₂.

What is His64's role in carbonic anhydrase?

Shuttles protons to buffer and prevents back reaction.

What is the significance of the buffer in carbonic anhydrase activity?

Increases reaction rate by aiding proton removal.

What role do restriction enzymes play in bacteria?

Cleave phosphodiester bonds in specific DNA sequences to defend against viruses.

How do restriction enzymes recognize host DNA?

Host DNA is protected by methylation to prevent restriction enzyme binding.

What distinguishes cognate DNA from noncognate DNA for restriction enzymes?

Cognate DNA is distorted to allow catalysis, while noncognate DNA isn't distorted and sees no cleavage.

What is the function of Magnesium (Mg²⁺) in enzyme activity?

Mg²⁺ activates water for nucleophilic attack and coordinates with Asp residues in enzymes.

How does ATP hydrolysis contribute to myosin's function?

ATP hydrolysis allows myosin to perform mechanical work through conformational changes.

What is the effect of Mg²⁺ on ATP binding in myosin?

Mg²⁺ stabilizes phosphates in ATP.

What is the rate-limiting step in myosin's ATPase activity?

The rate-limiting step is the release of inorganic phosphate (Pi), not the hydrolysis itself.

What are myosins classified as?

Myosins are classified as P-loop NTPases.

What is the structure of ATP synthase related to ATP synthesis?

Only β subunits in the F₁ subunit of ATP synthase catalyze ATP synthesis.