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Lecture 2

MCB 3020 Lecture Notes - Lecture 2: Hexokinase, Pentose, Citric Acid Cycle

Microbiology and Cell Science
Course Code
MCB 3020
Abdolkarim Asghari

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Microbiology Lecture 2 Exam 2
Environmental Effects on Enzyme Activity
Enzyme activity is significantly impacted by
o Substrate concentration
o pH
o Temperature
o Enzyme loses its 3-dimensional shape
o Loss of ezye’s structure and activity when temperature and pH too much above
o As you add more substrate, enzyme activity. Until enzyme becomes saturated (max) it
cannot increase any more no matter how much substrate you add
Enzyme Inhibition
Competitive inhibitor
o Directly competes with binding of substrate to active site
Noncompetitive inhibitor
o Binds enzyme at site other than active site
o Chages ezye’s shape so it eoes less atie. It ill preet sustrate fro idig
o Cannot overcome inhibitor by adding more substrate
Regulation of Metabolism
Important for conservation of energy and materials
Maintenance of metabolic balance despite chanes in environment
Three major mechanisms
o Metabolic channeling
o Regulation of synthesis of a particular enzyme (transcriptional and translational)
o Direct stimulation or inhibition of activity of a critical enzyme
Post-translationalafter protein is made, you do something to it. Add a group
to it.
Metabolic Channeling
o Differential localization of enzymes and metabolites
o Compartmentation
Differential distribution of enzymes and metabolites among separate cell
structures or organelles
Can generate marked variations in metabolite concentrations
Post-Translational Regulation of Enzyme Activity
o Two important reversible control measures
o Allosteric regulationby another molecule, you affect protein activity
o Covalent modification
Feedback inhibition
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