C1.1 Enzymes and Metabolism Flashcards
enzyme
mainly proteins that function as biological catalysts
catalyst
a substance that speeds up the rate of a chemical reaction
effective in small amounts and remain unchanged at the end of the reaction
what are enzymes
globular proteins
features of a globular protein
rounded and spherical
functional - catalysts
mostly soluble
irregular amino acid sequence
ex. haemoglobin, insulin, catalase
what is the shape of an enzyme determined by
folding of protein
amino acids in the primary structure of protein
DNA genetic code
metabolism
chemical reactions in the body
role of enzyme in metabolism
if there are no enzymes - reactions at slow rate
enzyme speeds up reactions
wrong collisions would occur
what is the point of enzyme specificity
metabolic processes can be closely controlled
how are enzyme specificty classified
according to the type of reaction they catalyse and names according to substrate
collision in enzyme action
parts are in continual random molecular motion
by chance collisions will occur
catalysis in enzyme action
substrates bind to the enzymes active site which undergoes induced fit to achieve the proper alignment and enable the enzyme to perform its catalytic function
release in enzyme action
products leave active site
enzymes left unchanged - can be reused
anabolism
synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers
building up
examples of anabolism
synthesis of proteins from amino acids
synthesis of polysaccharides from sugars
photosynthesis
endergonic
energy requiring reactions - anabolism
catabolism
breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers
breaking down
examples of catabolism
hydrolysis of macromolecules into monomers in digestion
exergonic
energy releasing reactions - catabolism
active site
the binding point where the substrate binds with enzyme to produce product
enzyme substrate complex
temporary structure formed when a substance binds to the active site of an enzyme
properties needed in active site
- binding to substrate molecule
- holding on to it during chemical reactions
- lowering energy of transition state
induced fit
binding of the substrates causing slight change in the shape of the enzyme to enhance catalytic activity
lock and key model
enzyme is the lock and substrate is the key
shape of the key must match lock and one key opens one lock
hand in glove OR induced fit model
in induced fit model because the active site change to fit substrate to ensure optimal fit
most enzymes follow this
why is movement needed in enzymic reactions
needed for a substrate molecule and an active site to come together
greater the kinetic energy greater the chance of collisions
immobilised enzymes
enzymes attached to an inert, insoluble material, enabling recovery, reuse and improved enzyme stability
features of immobilised enzymes
- more stable
- provide better environment for enzyme activity
how do enzymes get immobilised so they dont go away
enzyme may be entrapped between fibres or covalently bonded to a matrix
enzymes prevented from being washed away
example of immobilised enzymes in job
widely used method in food processing, pharmaceuticals and waste water treatment
enzyme immobilisation techniques
entrapment
absorption
covalent bonding
cross linking
affinity
advantages of enzyme immobilisation
- permits reuse of enzyme preparation
- product is enzyme free
- more stable and long lasting due to protection
denaturation in enzymes
occurs when weak intramolecular (hydrogen bonds) interactions within enzyme formed between different amino acids break
changes 3D shape of active site so enzyme substrate complex can’t form
effect of temperature in enzyme reactions
raising temperature speeds up a reaction
more kinetic energy means particles move faster and are more likely to collide
what can extremely high temperature do
cause bonds of enzyme and active site to break that maintain structure
it will loose its shape and stop workinge
effect of PH in enzymes
bonds are vulnerable to pH
each enzyme has an optimum pH for optimum rate
pH change causes change in shape of active site
activity of enzyme is reduced and rate of reaction slows
activation energy
initial energy input in the reaction
effect of substrate concentration in enzymes
increase causes rate of reaction to a certain point as there is more opportunity for collisions between enzyme and substrate
once all enzymes have bound a substrate any more substrate increase will have no effect on rate of reaction
transition state
point where there is maximum value of energy
effect of enzymes on activation energy
all chemical reactions require energy
- reactants need to have bonds weakened or broken
- molecules need to be reorientated
- new bonds need to be formed
importance of bonds
store energy because theyre made of energyen
how do enzymes catalyse chemical reactions by lowering activation energy
- wearing or breaking bonds in the substrates
- reorienting atoms in the substrates
- forming new bonds
