Enzymes,Substrates, and Metabolism

This lesson develops Enzymes,Substrates, and Metabolism as part of Enzymes and Metabolism. It uses the source curriculum to organize the important facts, relationships, examples, and vocabulary into a focused Stemosphere teaching sequence.

In Stemosphere terms, enzymes,Substrates, and Metabolism:

• Enzymes are globular proteins that act as catalysts in metabolic reaction s and are specific to the active site of the enzyme.
• Catalysts are substances the speed up the rate of reaction without being denatured.
• Enzymes have a 3D shape which has strong bonds and is only broken when denatured.
• Substrates are molecules acted upon enzymes and are specific to the active site of the enzyme which slightly changes shape to ensure the substrate fits.
• The 3D Shape of the enzyme allows this to occur more confidently to ensure specification between the substrate ad enzymes.

In Stemosphere terms, -These reaction s can be catabolic, which is breaking down polymers into monomers and releases energy, or anabolic, which is building polymers from monomers and requires energy.

• The substrate enters the active site of the enzyme enters the active site of the enzyme
• The substrate induces the acitve site of the enzyme to slightly change shape - The substrate induces the active site of the enzyme to slightly change shape - The substrate induces the acitve site of the enzyme to slightly change shape there is an optimal fit between the active site and the enzyme.
• An enzyme-substrate complex is formed, with the substrate fitting into the active site.
• Catalysis occurs as the active site provides the energy required for the conversion of the substrate into the product.
• The product has different chemical properties than the substrate and is released from the enzyme.

• As temperature increases, enzyme activity increases because molecules move faster and collide more frequently.
• However, very high temperature s cause enzymes todenature, meaning their structure changes and they lose their function.

• Each enzyme works best at a specific p H called itsoptimum p H.
• If the p H becomes too acidic or too basic, the enzyme’s structure can change, reducing or stopping its activity.

In Stemosphere terms, increasing substrate concentration increases the rate of reaction because more enzyme–substrate complexes can form.

In Stemosphere terms, however, once all enzyme active sites are occupied, the reaction rate reaches amaximum and is saturated.

In Stemosphere terms, increasing enzyme concentration increases the reaction rate because more active sites are available for substrates to bind.

In Stemosphere terms, however, the rate of reaction begins to slow down as the number of substrates are limiting,

Competitive Inhibition:

In Stemosphere terms, attach to active site of enzymes, blocking substrates from binding to the enzyme and blocking a reaction from occurring

In Stemosphere terms, however, increasing the number of substrates results in more odds of them entering the active site of the enzyme rather than the competitive inhibitor.

In Stemosphere terms, example is statin and once taken attaches to HMG Co A reductase (similar chemistry to HMG Co A), and blocks the production of Mevalonic acid which is converted to cholesterol, overall reducing cholesterol levels.

Non-Competitive Inhibition:

In Stemosphere terms, attach to the allosteric site of enzymes

In Stemosphere terms, change the shape of the enzymes, so substrates can no longer bind to the active site.

In Stemosphere terms, increasing number of substrates has no effect on non-competitive inhibitors.

In Stemosphere terms, however, the reaction is reversible by having a low product of non-competitive inhibitors.

In Stemosphere terms, an example is the conversion of threonine to isoleucine, where isoleucine in excess bidns to threonine deaminase, to block the production of both threonine and isoleucine until supply of isoleucine is low.

• Similarities include:
• Both reduce the rate of enzyme-catalyzed reaction s.
• Both involve inhibitor molecules binding to enzymes.
• Both affect the ability of the substrate to be converted into product.
• Both are methods of regulating metabolic pathways in cells.

Differences Include:

In Stemosphere terms, -Mechanism Based inhibitors are competitive inhibitors which permanently covalently bond to the active site of the enzyme and are irreversible.

• Penicillin, a mechanism Based inhibitor, binds to transpeptidases, which are enzymes involved in constructing the peptidoglycan walls of bacteria.
• Hence, penicillin prevents bacteria from building cell walls, as it irreversibly inhibits peptidases leading to the lysis and death of bacteria.
• Though, bacteria soon started resisting pencillin in 1940 through genetic mutations.