Enzymes Flashcards
define active site
- Active site is the 3D region within the enzyme that fits the substrate, the amino acid side chains align to bind to the substrate
define substrate specificity
enzymes only act on certain substrates
define activation energy
the minimal amount of energy required for substrates to undergo a chemical reaction
describe cofactor
this is a non-protein component of an enzyme that is required for activity and for the enzyme to catalyse a reaction but not the substrate itself
define coenzyme
a dissociable non protein which participates in the enzyme reaction and frequently interacts with multiple enzymes, can act to carry things between enzymes
define pro-enzyme
This is the inactive form of the enzyme in the cytoplasm before it is active, they can also be called the zymogen
they need to be chemically changed for it to work
describe the characteristics of enzymes
- Enzymes are protein catalysts
- Increase the rate of a biological reaction by lowering the activation energy, by finding an alternative route that has a lower activation energy
- They catalyse all the chemical reactions taking place in the cells
What are the bonds between the enzymes active site and the substrate molecules
- Hydrophobic interactions
- Salt bridges
- Hydrogen bonds
why are the products release
- Products are released when the reaction is complete as they no longer fit into the active site well
what will result in the enzyme not working
- Mutations that remove the important amino acids or change the shape of the enzyme will result in the enzyme not working
name the bonds that bond between the enzymes active site and the substrate
hydrogen bonding
salt bridges
hydrophobic interactions
describe the lock and key hypothesis
- Active site has a rigid shape
- Only substrates that match the shape can fit
- Substrate is a key that fits into the lock of the active site and forms an enzyme susbtrate complex
describe the induced fit model
- Active site is flexible
- The active site and substrate adjust to maximise the fit which improves catalyst
- There is a greater range of substrate specificity
- Model is more consistent with a wider range of enzymes
enzymes may recognise and catalyse a…
- single substrate (Absolute)
- group of similar substrates,(group)
- a particular type of bond (linkage)
if something has the word -ase in what does this mean
means it is an enzyme
e.g. lipase
describe how enzymes are named
- Can describe the function – oxidases – catalyse oxidation reactions
- Sometimes common names are used for the digestion enzymes such as pepsin and trypsin - these were named before nomenclature were used
- Sometimes the names describe the substrate and function, alcohol dehydrogenase oxidises ethanol
what is a prosthetic group
non-dissociable cofactor
what is a apoenzyme
enzyme lacking cofactor (inactive)
what is a holoenzyme
enzyme with a cofactor (active)
why do enzymes use cofactors and coenzymes
- they use these things and metal ions in order to gain multiple oxidations states as they cannot do this with oxygen
describe Heme as an example of an cofactor
- Heme is a common enzyme co factor
- Porphyrin ring containing iron
- Present in many enzymes involved in oxidation reactions for example
- Myeloperoxidase, Cyt C oxidase glutathione oxidase all contain heme as an essential cofactor
naem an example of a cofactor
Heme
name an example of a coenzyme
NAD
describe the function of NAD
- This is involved in moving electrons between enzymes
- Important in oxidation and reduction reactions
- Can exist in both oxidised and reduced forms therefore is able to carry electrons in both these directions
what is a vitamin
this is a required micro-nutrient, the organism cannot synthesize adequate quantities for normal health,
why does the body fail without vitamins
- Without vitamins and minerals body fails to function because they make the cofactors and conezymes
what are diseases associated with vitamin deficiency
- Beri-Beria deficiency in B1
- scurvey - deficiency in vitamin C
- pellagra - deficiency in vitamime B3
Name the different classes of enzymes
- oxidoreductases
- transferases
- hydrolases
- lyases
- isomerases
- ligases