Chapter 3- Enzymes Flashcards
What is an enzyme
These are biological catalysts that speed up chemical reactions that remain chemically unchanged
what type of proteins are enzymes
GLOBULAR
Intra-cellular VS extra-cellular
Intra- These are enzymes that are secreted in the cell and work in the cell e.g Respiratory cells
Extra- Enzymes are secreted in the cell and catalyse reactions outside the cell e.g Digestive cells
Describe the structure of enzymes
-They are globular proteins and have a 3D shape
-Their hydrophilic R groups orients to the outside of the molecule making it soluble
-Their Hydrophobic groups orient inwards which are able to maintain its shape due to hydrophobic interactions
-All enzymes have a cleft known as the active site where a substrate fits
Describe enzymes according to their tertiary structure.
> they are specific due to their complementary active site
Active site is determined by both the tertiary and primary structure
if the tertiary structure is altered in any way, then the active site will change and may hinder a substrate binding (enzyme- substrate complex)
The changes can be changed by Ph and Temperature
Catabolic VS Anabolic
Catabolic- BREAK DOWN of bonds
Anabolic - JOINING of small units
Explain the ‘Lock and key model’
~This occurs when the substrate is able to fit into the enzyme perfectly i.e like a lock and key.
~This occurs due to interaction of the R groups from the enzyme and the atoms of the substrate causing either a catabolic or anabolic reaction
when the reaction is done, the products leave the active site
Explain the ‘Induced fit model’
~This occurs when a substrate’s shape does not perfectly match the active site but just slightly
~Once it binds with the enzyme it changes it shape, allowing the enzyme- substrate complex to still be formed
What is the activation energy
This is when a certain amount of energy needs to be released before a chemical reaction starts
What are the factors affecting the rate of enzyme activity
-Temperature
-Ph
-Substrate concentration
-inhibitors
why is it easy to measure the rate of catalase hydrogen peroxide
Because one of its products is a gas
what can a colorimeter measure
The intensity of the colour produced
What happens when we continue to increase the substrate concentration
When this occurs, the enzyme concentration remains constant, hence can lead to every enzyme having a substrate and can lead to substrate molecules ‘queuing up’ as a result.
What is Vmax
This refers to maximum amount of enzyme activity. This is when all enzymes are bonded to a substrate
What happens when the temperature is too high
This can lead to hydrogen bonds breaking hence the shape of the active site can change and the complex cannot be formed
How does pH affect enzyme activity
It depends on the type of enzyme however most enzymes work at pH 7
pH refers to the concentration of hydrogen ions present.
Hydrogen ions react with the R groups which causes ionisation with the amino acids. This can affect the bonding and hence affects the shape of the active site.
How do we investigate pH
Using Buffer solutions. Each buffer solution has a specific pH yet maintain it even during a chemical reaction
What is competitive inhabitation
This is when another molecule has a complementary shape to the active site and is able bind to the enzyme, this can lead to inhibiting the enzymes activity.
How to reduce competitive inhibition
By increasing the substrate concentration then the binding can occur in the usual way.
Non competitive reversible inhabitation
This takes place when another molecule binds to another part of the enzyme rather than the active site. The binding can cause a disarrangement of the hydrophobic and hydrogen bonds in the enzyme, this affects the enzymes active site and hence inhibits its activity
How can NC inhabitation be essential
This can be used to control and balance out metabolic reactions. This is to avoid enzymes constantly churning out products all the time.
describe the end product inhibition
This is when there’s a chain of end products and usually one of the products are able to bind to one part of the enzyme which hence leads to inhibition of enxyme activity
what is the relationship between substrate concentration and Vmax
As Substrate conc. increases, the Vmax increases
What is Michaelas Menten constant
This is half the Vmax of substrate conc. -KM
what type of relationship does KM and affinity have
Inverse
as KM increases, the affinity decreases
mention 2 applications of the VM and KM
-Can help in biochem calculations
-can help understand enzyme efficiency
-enzymes performance can be compared
which solution is added to mix with an enzyme to immobilise enzymes
Sodium alginate
What is sodium alginate mixture added with
Calcium chloride
what does the Sodium alginate and calcium chloride form
A jelly which has each droplet create a small bead. when the enzyme is inside the bead we say it is immobilised
How do immobilised enzymes catalyse their substrates
The beads are kept in a column. The substrate are inside a liquid and trickle down onto the column where it runs through the enzymes. The enzyme catalyses the substrate and the remaining liquid (products) emerge from the bottom and are purified
List 3 advantages of using immobilised enzyme
- no enzyme inhibition
- enzyme is reused
- product is not contaminated with the enzyme
- enzyme is easily recovered
-less likely to denature
