3- enzymes Flashcards
(12 cards)
Which statement is true of a competitive enzyme inhibitor?
effects can be overcome by adding more substrate
Which statements about enzyme inhibitors are correct?
1 - competitive inhibitors may be similar shapes to the substrate
2 - competitive inhibitors bind to the active site
3 - non-competitive inhibitors alter the shape of the enzyme
4 - non-competitive inhibitors bind to the substrate
1, 2, 3
Why do large increases in the temperature or pH alter enzyme activity?
1 - they change the three-dimensional shape of the enzyme
2 - they disrupt hydrogen and ionic bonds in the enzyme
3 - they increase hydrophobic interactions in the enzyme
1, 2
What is the effect of an enzyme in an enzyme-catalysed reaction?
effect on activation energy+energy yield
decreases the activation energy and has no effect on the energy yield
Strength of bonds in enzyme
weak H bonds- stabilise secondary structure of alpha-helix/beta-pleated sheets
ionic bonds(electrostatic interactions) contribute to overall tertiary structure between side chains
Van der Waals interactions stabilise protein’s tertiary strcuture by allowing hydrophobic side chains to interact with each other
disulfide bonds(covalent) strong- between sulfure atoms of 2 cysteine amino acids in tertiary structure
peptide bonds strongest
what happens when enzyme denatured
bonds are broken between the R groups of the amino acids in the polypeptide chains of the enzyme
tertiary structure of the enzyme is altered
shapes of the active site and the substrate are no longer complementary
What is the definition of the Michaelis-Menten constant, Km, for an enzyme
substrate concentration that gives half Vmax
What determines the specificity of an enzyme
covalent and other bonding between R groups of the polypeptide
By which method can immobilised enzymes be produced?
enclosing enzymes within a partially permeable membrane
by: attach insoluble, inert material (calcium alginate). forms gel capsule
+: immobilising enzymes
- easily separated from products and reused
- more stable enzyme- can withstand changes to pH+temp in solution
- allows more product formed
what makes an enzyme globular
- spehrical shaped
- water soluble - AMINO ACIDS WITH hydrophilic R groups on outside, phobic on inside
cell signalling
excess/deficit of __ stimulates immune system cells
- receptor detects when increased conc of __
- secretes ligand, which is cell signalling molecule
- ligand binds to CSM receptors due to complementary shape
- triggers response
(enzyme cascade triggered)
