Th1L07 Regulation of enzyme activity


Medicine Y1 (Theme 1 | Cells and organelles) Mind Map on Th1L07 Regulation of enzyme activity, created by Emma Allde on 17/08/2016.
Emma Allde
Mind Map by Emma Allde, updated more than 1 year ago
Emma Allde
Created by Emma Allde over 7 years ago

Resource summary

Th1L07 Regulation of enzyme activity
  1. Allosteric regulation
    1. regulation of a protein by binding an effector molecule at a site other than the protein's active site
      1. that site is the allosteric site
        1. allow effectors to bind to the protein, often resulting in a conformational change involving protein dynamics
        2. Sigmoid curve (compared to hyperbolic curve of M-M kinetics)
          1. Allosteric activator
            1. Opens up active site, making it more open to substrate
              1. more or less effective active site
              2. Negative allosteric effectors
                1. Eg. ATP and citrate on phosphofructokinase (metabolism)
                  1. ATP can act as positive regulator during glycolysis if there is not enough ATP and citrate
                2. Positive allosteric effectors
                  1. Eg. - "phosphoenolpyruvate (PEP) and fructose 1,6 bis phosphate on pyruvate kinase
                    1. PFK acts as a positive allosteric regulator of phosphenyolpyruvate to pyruvate (a later step in glycolysis); good example of co-ordinated regulation
              3. Pharmacological altering of enzyme activity
                1. Covalent modification by other enzymes
                  1. Most common form is the addition or removal of phosphate from Ser, Thr, Tyr, His residues
                    1. Dephosphorylation of serine 14
                      1. by phosphorylase phosphatase
                      2. Glycogen synthase kinase 3
                        1. phosphorylates at several serine resides; inactivates the enzyme entirely
                      3. Glucose metabolism
                        1. Coordinated regulation of synthesis and breakdown of glycogen via adrenaline and glucagon
                          1. Shows how protein phosphorylation may be increasing or decreasing activity of even catalysis of a different reaction
                          2. Phosphorylation (regulation of glucose metabolism)
                            1. Single cascade system
                              1. Increases activity of glycogen phosphorylase, which is responsible for degrading glycogen
                                1. occurs by phosphorylase kinase serine 14 and requires ATP; ALSO reduces activity of glycogen synthase (synthesises glycogen)
                                2. Other
                                  1. Adenylylation or AMPylation (Tyr residues, ATP to PPi)
                                    1. Uridylylation (Tyr residues, UTP to PPi)"
                                  2. Induction or repression of enzyme synthesis
                                    1. e.g. High blood glucose levels lead to an increase in insulin production
                                      1. Insulin increases rate of synthesis of key enzymes involved in glucose metabolism
                                        1. Glucokinase, phosphofructokinase, pyruvate kinase
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