2.4 Enzymes Flashcards
What is the name of the molecule made when an enzyme and substrate bind?
Enzyme-substrate complex
What is the name of the molecule formed after the enzyme has broken down the substrate?
Enzyme-product complex
What is competitive inhibition?
When the inhibitor and the substrate are competing for the active site, so that if the inhibitor gets to the active site first, the substrate cannot bind and form a enxyme-substrate complex.
What is non competitve inhibition?
When an inhibitor attaches to the allosteric site which induces conformational change to active site, which prevents enzyme substrate complexs from forming.
What do competitive and non competitive inhibitiors look like?
Competetive inhibitors reach the same rate of reaction as one with no inhibitor, but takes a greater concentration of substrate to reach that point.
Non-competitive inhibitors never reach the same rate of reaction as the inhibitors induce conformation change in the active site, so they will never work at the same rate.
What factors affect the level of inhibiton caused by the inhibitor?
- The concentration of inhibitor
- the concentration of substrate
- the relative binding power of inhibitor/substrate
What is the induced fit theory?
1) substrate comes into contct with the enzyme
2) substrate induces conformational change of the enzyme in order to bind to the active site
3) Substrate bonds to ‘R’ groups on the amino acid of the enzyme
What does saturation mean (in terms of ezymes)
When all acitve sites are in use. In this case, the limiting factor is the concentration of enzymes.
What is End product inhibition?
When the substrate has been broken down into the product, sometimes the product may stay tightly bound to the enzyme. This way more substrates cant be broken down, so the enzyme cannot form more of the product than the cell requires. This is an example of negative feedback.
How are metabolic sequences controlled by enzymes?
- The product of one enzyme will then be broken down further by another enzyme further down the chain
- Cells dont want to over-accumulate the end product, so they may use end product inhibition
- The products of the final enzyme then attach the allosteric site of the first enzyme to prvent the pathway from running
- it is reversible so when the cell needs more of the product it will detach from the enyzme and the pathway can run again
What are cofactors?
Molecules which attach to an enzyme in order for it to work. Some cofactors (prosthetic group) are permanently bound and part of the enzyme’s structure.
What is a CoEnzyme?
A small organic molecule which binds temporarily to the active site of an enzyme in order for it to work.They get chemically changed during the reaction so need to be recycled.
What is a prosthetic group?
A cofactor which permanently bonds, through covalent bonds, to an enzyme, for example, the haem group in haemoglobin.
How do metallic ion cofactors enable some enzymes to work efficiently?
They temporarily attach to the enzyme or substrate to aid the formation of enzyme-substrate complexes
What is the difference between organic coenzymes and metallic ion cofactors?
Organic coenzymes are chemically changed during the reaction and need to be recycled to their original state after used. Metallic cofactors can also often be permanently bound and are not used up during the reaction.
