2.5: Enzymes

Can products be used as substrates to create an end product?

Yes. Metabolism refers to all the reactions that take place in a cell, and biochemical/metabolic pathways refer to the chain of enzyme-catalyzed reactions in order to form an end product. Such processes include glycolysis or the Calvin cycle.

What does it mean for an enzyme to reduce the activation energy of a reaction?

Activation energy: the initial input of energy needed for a chemical reaction. Seen from a graphical representation, a chemical reaction without an enzyme requires significantly more activation energy than a chemical reaction with an enzyme. This means enzymes not only catalyze reactions to make them faster, but reduce the energy needed to produce the reactions as well.

What is the fundamental rule between an active site and a substrate, and how can we understand this?

Active sites have enzyme-substrate specificity, meaning they can only bind to one another if they share a chemical attraction and are compatible in shape. If they can do this, this forms an enzyme-substrate complex, meaning they can produce a chemical reaction.

What does it mean for an enzyme to be at its optimum? What conditions have to be at an optimum? Is 'optimum' a good thing?

This is when the rate of reactions are at its highest. Enzymes should always work at their optimum. Such conditions that determine its optimum energy are temperature, pH, and substrate concentration.

What is an active site?

An active site is used to bind with a substrate in order to undergo a chemical reaction. However, the active site has enzyme-substrate specificity, meaning it can only bind with substrates that are complementary in shape. This can be demonstrated through the lock and key hypothesis.

What are the conditions that cause a substrate to bind with their correct enzyme?

Collision: process by which the enzymes and substrates can collide to bind, particularly at random and within dissolved water to allow the movement of particles. The substrate must also be at the correct orientation to the enzyme's active site in order to successfully collide.

What are the four benefits of enzymatic immobilization?

Concentration of substrate can be increased as the enzyme is not dissolved - this increases the rate of reaction Recycled enzymes can be used many times, o Separation of the products is straight forward (this also means that the the reaction can stopped at the correct time). Stability of the enzyme to changes in temperature and pH is increased reducing the rate of degradation, again resulting in a cost saving.

What happens when an enzyme is not working at its optimum?

Denaturation: the process by which an enzyme's active site changes shape, which results in the substrates being unable undergo a chemical reaction. This can disturb the metabolic pathways used to perform certain functions, which can be dangerous to the body.

What is it called when an enzyme binds with a substrate to form a chemical reaction?

Enzyme substrate complex.

What is an enzyme and its function?

Enzymes are proteins which work to speed up the rate of a chemical reaction (catalyze)

Give an example of an enzyme and its function.

Lactose, commonly found in milk and dairy products, is broken down by the enzyme lactase in order to produce glucose and galactose for the small intestine. Many people struggle to break down lactose in their bodies, so lactose is oftentimes synthetically broken down by lactase in lactose-free dairy products. One form of biotechnology that performs this task is through lactase beads, which immobilize the enzyme and break down lactose milk when it runs through.

What is a substrate?

Substrates are molecules that bind with an enzyme in order to produce a chemical reaction that can either build or break down the substrate.

What is the rather modern understanding of the fundamental rule between an enzyme and a substrate in order to bind?

The induced fit model of enzymes explains the idea that enzymes can undergo conformational change, which is the process of the active sight slightly changing shape to bind with a substrate. This was found based on observations of enzymes binding with unexpected substrates. It shows that certain enzymes do not just bind with a single type of substrate.