FUNCHEM 20: Catlaysis, Enzymes and Michaelis-Menten equation

What is a catalyst?

A catalyst is a substance that increases the rate of chemical reaction without being used up in the reaction

What is the role of functional group in enzye

The functional group in the active site of the enzyme assist in balancing the bond breaking parts of the mechanism with the bond making parts

Anything that disrupts this structure will reduce the enzyme catalytic power

Explain the Lock and Key Theory of the enzyme

Active Site within the structure of each enzyme

It has a specific shape, which gives each enzyme its specificity

Only molecules of the right shape can be a substrate for the enzyme

The enzyme and the substrate slot together forming a complex

In this complex the substrate reacts at a lower activation energy

This may be due to the bonds within it being deformed and stressed in the complex making them more likely to react.

Once the reaction has been catalyzed, the product is no longer in the right shape to be in the active site and the complex breaks up, releasing the product and freeing the enzyme for further catalytic action

Explain the Induced-fit theory

Enzyme undergoes conformational change as the substrate approaches and start to bind

Proteins are flexible molecules whose overall structure is maintained by weak intermolecular interactions.

At any given time, these can be disrupted by small changes in their vicinity

The enzyme and substrate must still have complementary surfaces

Why is enzyme temperature dependent?

Hydrophobic interactions and salt bridges break as the increase in temperature causes the enzyme’s structure to “wiggle around”

Why are enzymes ph dependent?

salt bridges depend on ionic charges for their bonding power

Anything that neutralizes such charge will destroy the salt bridges and make the folded structure of enzyme less stable.

Increase of ph- will take an H+ from an NH₃⁺ group and neutralize its charge

Decrease in ph- will put an H+ on a COO^-.

How do you find K_m, the Michaelis- Menten constant

What is the Michaelis Menten equation

What is the rate equation that relates to the Michaelis Menten Equation

At low substrate concentration it is a first order reaction, what’s the rate

At high substrate concentration- it is a zero order reaction

what’s the rate equation