Chapter 6 Enzymes

Metabolic Reactions Metabolism – All the reactions that happen in the cell – Reactions have two sides 1.What goes into the reaction  Reactants 2.What comes out of the reaction  Products Reactants  Products A + B  C + D

Metabolic Pathways Reactions that happen in cells are a series of linked reactions

Chemicals are changes in a metabolic pathway by Enzymes An Enzyme is a protein that acts as a catalyst to speed chemical reactions. The reactants in a enzymatic reaction are called the Substrate Substrate  Product

Where is the enzyme? Where is the Substrate?

Energy of Activation Enzymes speed up reactions by lowering the reactions Energy of activation Energy of activation  the energy required to make a reaction occur Which reaction has the Enzyme present?

Enzyme Substrate Complexes Enzyme + Substrate  Enzyme Substrate Complex  Enzyme + Product Active site  The part of the enzyme that fits with the substrate Enzymes change shape slightly so they can fit together with the substrate better.  this is called Induced Fit Model

Types of Enzymes Enzymes only complex with a specific substrate so they are named after their substrate Enzyme names often end with “-ase” SubstrateEnzymes LipidsLipase ProteinsPeptidase NucleotidesNuclease MaltoseMaltase

Factors that affect the enzymatic reactions 1.Substrate Concentration – The greater the substrate  The more reactions 2.Temperature – As temperature increases  More reactions – If temperature is too high  Enzyme denatures 3.pH – Every enzyme works at a specific pH

Where would you find these enzymes? Stomach Mouth Kidney and Small intestine

Factors that affect enzyme reactions Enzyme Concentrations – The more Enzyme the more reactions – The body may want to regulate the reactions so it will prevent an enzyme from working 1.Competitive Inhibitors 2.Non-competitive Inhibitors

Competitive Inhibitor A molecule that is very similar to an enzymes substrate will bind with the active site. But since its the wrong molecule, no product is made

Non-competitive Inhibitor A molecule binds to an enzyme. But it does not bind to the active site. The molecule changes the shape of the protein so it no longer works. The enzyme will work when the non-competitive inhibitor leaves

S Substrate Non-Competitive Inhibitor Products Enzyme

Using Enzyme inhibitors the body can regulate how much product is being made The concentration of the product is always within a certain range It regulates it by Feedback Inhibition

Heavy Metals and Enzymes Heavy Metals  Metals that are towards the middle of the periodic table. They are considered poisonous. Heavy metals will interact with the “R” group of certain amino acids. How would this affect an Enzyme? When the “R” group is changed then the tertiary structure changes. If the tertiary structure is changed  The Protein is changed

Are Heavy Metals competitive inhibitors or non-competitive inhibitors? They are non-competitive inhibitors Because they are not competition for the active site

Enzyme Cofactors Some enzymes need an inorganic ion or a organic molecule to help the enzyme function Cofactors  inorganic ions like zinc or iron Coenzymes  organic non-protein molecule Vitamins  are required to help synthesis coenzymes. Some vitamins are coenzymes.

Cofactor

Coenzymes

Coenzyme

So what tells the body to do all of these metabolic reactions? There is a gland in the body called the Thyroid The Thyroid releases a hormone called Thyroxine If this hormone is released it tells the body to increase metabolic functions