Regulatory Strategies of Enzymes Flashcards
Binding energy
Free energy released in the formation of a large number of weak interactions between enzyme and substrate that is in transition state
Covalent catalysis
Making covalent bonds to substrate
Increases binding energy
General acid-base chemistry
Movement of electrons at active site of enzyme
Increases binding energy
Catalysis by approximation
Bring active site and substrate together
Increases binding energy
Metal ion catalysis
Using a cofactor to increase the binding energy
Goal of proteolysis
Enabling attack of a molecule that doesn’t want to be attacked (amino acid chain can be stabilized through resonance, making it less susceptible to nucleophilic attack)
Serine as a nucleophile
Serine splits a protein chain into 2 pieces by latching onto the carbonyl group
Water can then attach to the carbonyl, breaking off the serine
Catalytic triad
Part of serine protease
Stronger nucleophile than -OH
3 polar amino acids attached to an enzyme base
How serine protease performs proteolysis
Catalytic triad reacts with the carbonyl group of the protein to create a reactive nucleophile and the enzyme portion stabilizes the transition state
Which of the 3 amino acids in the catalytic triad are essential for its function
All 3 amino acids are critical to the function of the catalytic triad
Reason why reaction of serine protease with nonfunctional catalytic triad is faster than the uncatalyzed reaction
Even without the catalytic triad, the enzyme backbone can still bind to substrate
Common reaction of proteases
Nucleophilic attack of carbonyl carbon of target protein
Allosteric regulation
Regulate enzyme from spot other than active site
Isozymes
Multiple forms of an enzyme (different amino acids, same reaction)
Similar active sites, different allosteric sites
Isozymes and enzyme regulation
Having more than 1 type of enzyme for a specific function can enable enzymes to work in different parts of the body
Temporal and spatial separation of enzymes
ATP as an allosteric modifier of metabolic enzymes
Energy sensor: adding ATP to an enzyme can tell the enzyme if there is enough energy for it to be able to work
End products of catabolic pathways and allosteric regulation
Final products of catabolic processes allosterically regulate the original enzyme
Products of catabolic processes commonly inhibit at points of energy investment
Heterotrophic effect
Different molecule from substrate influences rate of reaction
Homotrophic effect
Substrate influences rate of reaction
Pros of phosphorylation
2 negative charges disrupt/create electrostatic interactions
3 potential hydrogen bonds
Shifts balance of free energy
Amplification of signal
Can be reversible through actions of phosphatase
Domains of kinases
Domain specific for binding to substrate
Domain specific for regulation by ATP binding
Zymogen
Molecule that is cleaved to make a functional enzyme
Precursor to enzyme
Zymogen cascade
Amplification: 1 zymogen turns on the next which turns on the next…
Results of proteolysis
Cutting a protein changes its structure and makes new ionic charges
