Enzyme Regulation Flashcards

1
Q

Compartmentaltion

A
  • ensures metabolic efficiency and simplifies regulation
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2
Q

Regulatory Enzymes

A
  • have special properties leading to regulatory roles in metabolism
  • allosteric and covalently modulated enzymes
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3
Q

Allosteric regulation

A
  • enzymes are highly regulated by binding small molecules that can either decrease or increase activity
  • Feedback inhibition: first enzyme in a multi-step pathway inhibited by the final product of the pathway
  • modulator binds non-covalently to site other than active site
  • negative modulator inhibit, positive stimulate
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4
Q

Homotropic allosteric regulator

A
  • a substrate for its target enzyme
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5
Q

Heterotrophic allosteric regulator

A
  • molecule that is not also the enzyme’s substrate

- can be activator or inhibitor

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6
Q

ATCase

A
  • CTP inhibits it, ATP activates it

- binding sites for allosteric modulators are on the regulatory units

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7
Q

Covalent modifications

A
  • regulate metabolic flow by post-translationally modifying key metabolic enzymes and proteins
  • occurs by post translational modification of AA side chains
  • regulatory modifications: phosphorylation acetylation, methylation, ADP-ribosylation
  • Structural modifications: Prenylation, glycosylation, hydroxylation, and FA acylation
  • Proteolysis - irreversible
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8
Q

Phosphorylation

A
  • reversible
  • introduces 2 negative charges on proteins
  • kinases add a phosphate to hydroxyl side chains
  • phosphatase so remove a phosphate from a phosphorylated side chains
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9
Q

Reversible Acetylation of Proteins at e-AMino Groups of Lys Residues

A
  • acetylation neutralizes the positive charges on Lys residues
  • sirtuins - involved in deacetylation
  • SIRT1 - nucleus
  • SIRT3 - mitochondria, is the major mitochondrial NAD+ dependent deacetylase involved in tumors suppression as well as many other physiological processes
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10
Q

Post-translation modification regulation

A
  • rapid
  • doesn’t require new proteins to be made or degraded
  • easily reversible
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11
Q

Glycogen Phosphorylase

A
  • activity of glycogen phosphorylase involves covalent modification, allosteric regulation, and a regulatory cascade sensitive to hormonal status that acts on the enzymes involved in phosphorylation an dephosphorylation
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12
Q

Regulation of Metabolic pathways

A
  • allosteric regulation by ADP/ATP and NAD+/NADH levels
  • feedback inhibition
  • PTM of metabolic enzymes
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13
Q

Regulation of Enzyme activities by proteolysis

A
  • irreversible
    -near ubiquitous
  • rapid mobilization of an activity in response to physiologic demand
    -Met excision
    -signal peptide removal during translocation of a protein
    -N and C terminal processing proteins into their active forms
    Ex blood coagulation cascade and zymogens
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