Enzymes are biological catalysts that regulate almost all the cellular reaction The general characteristics of enzymes
Speed up the rate of chemical reaction Not destroyed by the reactions they catalyse @ can be reused Highly specific – each enzyme can only catalyse one kind of substrate Needed in small quantities Most enzyme-catalysed reaction are reversible Most enzyme require helper molecules called cofactors Sensitive towards changes in pH Sensitive towards changes in temperature
Slowed down or completely stopped the activity of an enzyme
Help the activity of an enzyme to function well
Ribosomes
Ribosomes are the site of protein synthesis Enzymes are proteins Ribosomes are also the site of enzymes
An enzymes is named according according to the name of the substrate substrate it catalyes
SUCROSE SUCRASE LIPID LIPASE
adding the suffix –
ase at the end of the enzymes
CLASS
ACTION
Hydrolase
Add water
Ligase
Combines 2 molecules
Oxyreduction
Oxidation & Reduction
Lyase
Destroys chemical bond C-O , C-C , C-N
Transferase
Transfers the functional group to other molecules
Isomerase
Rearrange the functional group
Cell
Enzymes synthesised and retained in the cell for the use of the cell itself
enzymes
Formed on free ribosomes in the cytoplasm
These enzymes can found in the cytoplasm, nucleus, mitochondria and chloroplasts
Cell
enzymes Enzymes synthesised in the cell but secreted from the cell to work externally
Synthesised on ribosomes attached to the rough ER
Eg : digestive enzymes produce in the pancreas – secreted to the duodenum to work
Enzymes
Substrate
Active site
Enzymes Substrate - Complex
Product
The active site free to receive another substrate
Cell membrane Enzymes moved out in secretory granule to be excreted
Golgi appparatus
Extracellular enzymes
9 Polypeptide chain synthesis at ribosome on a rough endoplasmic reticulum
tRNA brings an amino acid to ribosome
ribosome
2
3
Polypeptide molecules going into the rough ER
8
4 mRNA copies instruction from DNA and moves out
proteins move through golgi apparatus
7
1 5
Proteins enters into vesicles
In the golgi apparatus, proteins is further modified before being sent to the cell membrane as an extracellular enzymes
6
Vesicles from ER carrying proteins to Golgi apparatus
Cell membrane
Golgi appparatus
tRNA brings an amino acid to ribosome
Enzymes moved out in secretory granule to be excreted
Polypeptide chain synthesis Polypeptide at ribosome on a rough endoplasmic moleculesreticulum going
In the golgi apparatus, proteins is further modified before being sent to the cell membrane as an extracellular enzymes
into the rough ER
ribosome mRNA copies instruction from DNA and moves out
Extracellular enzymes
proteins move through golgi apparatus
Proteins enters Vesicles frominto ER carrying vesicles proteins to Golgi apparatus
Temperature
Low • movement of substances slowly. • enzyme-catalysed reaction slowly.
Optimum • movement of substances increase. • chances of colliding with active site of an enzyme molecules. • enzyme-catalysed reaction increase
High • more enzymes molecule denurated. • rate of reaction falls. • enzymes-catalysed reaction decrease. • less product produce.
Correct pH
Low pH
High pH
(acidic)
(alkaline)
Substrate
Substrate
Substrate
-
+
+
-
+
-
Active site
+
-
Charge on active site match those of substrate enzyme-susbtrate complex form
+
+
Too many H+ ions active site repels substrate enzyme-subatrate complex cannot form
-
-
Too many OH- ions active site repels substrate enzyme-subatrate complex cannot form
enzymes
substrate
• little substrate • many enzymes • rate of reaction low • eg : 2 molecules per unit time
• more substrate • still enzyme > substrate • rate of reaction increase • eg : 4 molecules per unit time
• enzyme = substrate • highest possible reaction rate • eg : 6 molecules per unit time
• substrate > enzyme • rate of reaction is still the same • eg : 6 molecules per unit time
Rate of reaction
Highest rate
Active site still not fully used
Low
Active site fully used ďƒ same rate of reaction ďƒ straight line
Substrate = enzymes
Substrate concentration
Application
Enzymes
Fish industry Protease
Uses Remove the skin of fish.
FIND THE APPLICATION AND THE USES FOR THE LIST OF ENZYMES BELOW 1) RENIN in dairy industry 2) LIPASE in dairy industry and biological detergents 3) AMYLASE in baking industry, textile industry and paper industry 4) TRYPSIN in processing industry and medical analysis 5) PROTEASE in leather tanning industry