Enzymes Proteins in Action. Enzymes are Proteins Most enzymes are globular proteins. Like all...
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Transcript of Enzymes Proteins in Action. Enzymes are Proteins Most enzymes are globular proteins. Like all...
EnzymesEnzymes
Proteins in Action
Enzymes are ProteinsEnzymes are Proteins
Most enzymes are globular proteins.
Like all proteins, enzymes are made up of chains of amino acids.
Each enzyme has a specific shape in order to carry out its function.
Enzymes are catalystsEnzymes are catalysts
Catalysts are substances that lower the activation energy of a chemical reaction.
Enzymes make it easier to put together or take apart molecules.
Enzymes are specific. Each enzyme does only one kind of job.
Enzyme activity is regulated by the molecules they catalyze, or by other molecules.
Activation EnergyActivation Energy
Catalysts reduce the energy needed to carry out a reaction.
Enzyme StructureEnzyme Structure
An enzyme has an active site, into which fits a substrate, like a key into a lock.
Enzyme FunctionEnzyme FunctionThe substrate fits
into the active site in the enzyme.
The active site changes shape as it forces the reaction to take place.
The product is released, and the
active site returns to its original shape.
Metabolism and EnzymesMetabolism and Enzymes
Many biological functions, including metabolism, are enzyme driven, and may involve multiple
enzymes.
Enzyme RegulationEnzyme Regulation
Feedback loops often regulate enzyme reactions. For example, the product of a reaction may
inhibit one enzyme in the reaction.
Allosteric InhibitionAllosteric Inhibition
The regulator molecule changes the shape of the active site.
Competitive InhibitionCompetitive Inhibition
A molecule with a shape similar to the substrate fits into the enzyme’s active site. Some poisons work this way.
Reaction speedReaction speed
The speed of an enzyme-catalyzed reaction depends on:
temperature
pH
salinity
concentration of the substrate
concentration of the enzyme
Enzyme SpecificityEnzyme Specificity
Each enzyme carries out one job, and one job only.
The lock-and-key fit between substrate and enzyme allows the enzyme to fit only certain substrates.
Any one enzyme will either put molecules together or break them apart. The same enzyme won’t do both.