Unit 3 AOS 1.3: Enzymes and Proteins

The energy required to break original bonds in the reactants.

Denaturation occurs when the shape/structure of the active site is altered. It is a permanent change.

NADH donates electrons to substrate which turns if back into NAD+ and NADH removes electrons from the substrate to be turned back into NADH. Many reactions involve the removal of electrons from the substrate to form the product.

Important in photosynthesis. NADP+ removes electrons from the substrate to be converted into NADPH and NADPH donates electrons from the substrate to be converted into NADP+.

The survival of living things relies on chemical reactions but since living things exist at relatively low temperatures we need enzymes to speed up reactions that we need to occur quickly like metabolic reactions.

organic nonprotein molecules that assist with the functioning of enzymes.

Enzymes are large specific protein catalysts that reduce the activation energy required to initiate a reaction, hence speeding up a reaction.

They act as organic catalysts by increasing the rate of chemical reactions.

The presence of an active site which is a region that has a complementary 3D shape to the substrate.

The energy required to initiate a reaction.

The substance on which an enzyme acts

Substance that accelerates a reaction.

Endergonic reactions need energy to perform and the products have more energy than the reactants.

Exergonic reactions give off energy as heat and the products have less energy than the reaction.

The lock and key model and the induced fit model.

It states that the active site is an exact match for its substrate.

It states that the active site is a close match for the substrate, but the binding of the substrate induces a conformation change allowing it to bind.

The functioning of enzymes relies heavily on the 3D shape of their active site. Any factor that alters this will affect the enzyme as it may inhibit the formation of substrate-enzyme complexes.

All enzymes have optimal temperatures where they operate most efficiently. When the temperature increases, the molecules have more kinetic energy, resulting in more collisions between the substrates and enzymes. However, if the temperature is increased beyond, this causes the enzyme to denature and the bonds of the enzyme break leading to a unraveling of the tertiary structure. This leads to a loss of its conformation 3D shape and therefore the substrate can no longer bind to the active site.

There is less kinetic energy available and the movement between the enzymes and substrates will decrease which slows down the reaction and enzymes will eventually become inactive.

IF the pH deviates significantly from its optimum value then this will causes changes within the hydrogen bonding within the enzyme changing the 3D structure and thus inhibiting its activity.

- it will affect the intra and intermolecular bonding of an enzyme and thus possibly change its tertiary structure

There are two, competitive and non-competitive inhibitors.

Where the inhibitor covalently binds to the enzyme, permanently altering the structure of the enzyme.

Competitive inhibitors work by having a similar shape to the usual substrate molecule and so they can bind to the active site of the enzyme, preventing the formation of enzyme-substrate complexes.

By increasing the concentration of the substrate, as this increases the likelihood that a substrate will interact with the active site instead of an inhibitor molecule.

They work by binding to an allosteric site on the enzyme. By binding to the allosteric site, it causes a conformational 3D change within the enzyme, causing the shape of the active site and preventing it from binding to its substrate.

Reversible

reversible

a non-protein molecule or ion that is required for the proper functioning of an enzyme - are considered helper molecules

Dissolved substance

Liquid in which the solute is dissolved

Solute mixed in a solvent.

Enzymes are specific for only one reaction. This is why you use the word specific!

Breaks down a substrate into two products.

Enzyme that joins together substrate molecules.

No

Endergonic reactions require energy and products have more energy than the reactants. eg: photosynthesis

They release energy and where the products have less energy than reactants. Example is cellular respiration.

Increases the rate of reaction

Increases the amount of product.

Yes they are soluble globular proteins that consists of one or more polypeptide chains.

oligomers with each enzyme consisting of two or mroe polypeptide chains that are called subunits.

Specific

Enzyme can only act on one substrate only.

Enzyme can only act on one kind of chemical bond.

Meaning that an enzyme can only act on molecules with particular functional groups.

Inactive enzymes that are only activated in resonse to relevant signals.

A molecule that binds to an enzyme, reducing activity by interfering with the enzyme in some way.

Allosteric site which distorts the 3D shape so it can no longer bind to its substrate

Adenine triosphate is a coenzyme for endergonic metabolic reactions.

ATp participates in a coenzyme in many enzyme-catalysed reactions as an additional reactant where it is converted to a compound called ADP with the release of a phosphate group. This breakdown releases energy which is used to fund the conversion of the substrate into the product.

supplies chemical energy for endergonic reactions.

ATP diffuses from an area of high concentration in the mitochondria to an area of low concentration in the ribosomes where it is being used to create proteins. Then the ADP produced in this process diffuses back to the mitochondria where it is being used up to create ATP.

ATP works in a way that means it is a coenzyme. When a substrate is joining two substrate molecules together, that requires energy. The way this happens is that the ATP goes into the active site of the enzyme and in the process, the ATP is broken down and changed into ADP.

Think NAD+ is ADPa nd NADH is ATP, wherin the hydrogen is broken off and a little energy is produced.

NADPH accepts electrons and hydrogens from the splitting of water. Oxidised form NADP+ +2e- +2H+ >>> NADPH + H+.

Endergonic

exergonic

They are used up in a reaction and have to be discarded.

Break things down

Build things up.

End product inhibition the end product of a metabolic pathway binds non competitively to the first enzyme in the pathway, stopping the production of the final product.

tightly bound cofactors or coenzymes that are necessary for enzyme function - are permanently bonded
have a tightly bound heme containing group

temperature, pH, enzyme and substrate concentrations

catalyze oxidation-reduction reactions that involve the transfer of o and h atoms

transfer functional groups from one substrate to another

catalyze cleavage with the addition of water

cleave bonds in a substrate but not by hydrolysis

catalyse the change in arrangement of atoms ion a molecule

catalyze the joining of molecules by a new bond.

HELD together by weak hydrogen bonds and ionic bonds between opposite charges - is weak to allow for easy release of product

they act upon the reactant molecules and change them in some way that makes it easier for the formation or breaking of bonds to occur

The maximum rate of the reaction where all enzymes are saturated with substrate

The substrate concentration at half the Vmax - the lower m is, the higher the affinity of enzymes for substrates

Poisons such as cyanide that inhibit enzymes needed for aerobic respiration in electron trnasprt chain- cytochrome c oxidase

Inhibitor bonds noncovalently to the enzyme inhibiting its function- is not permanent and the inhibitor can dissociate from the enzyme

A type of regulation that responds to a change in conditions by initiating responses that will counteract the change- too much product so stop producing