Section 2.5: Enzymes

Biology

Activation Energy

• Energy that is needed for a chemical reaction to begin

Activation Energy

• Energy that is needed for a chemical reaction to begin

• Once the chemical reaction begins it can continue on its own at a certain rate

Activation Energy

• Energy that is needed for a chemical reaction to begin

• Once the chemical reaction begins it can continue on its own at a certain rate

• The activation energy generally comes from an increase in temperature

Activation Energy

• Energy that is needed for a chemical reaction to begin

• Once the chemical reaction begins it can continue on its own at a certain rate

• The activation energy generally comes from an increase in temperature

• But, the reaction may be very slow

Activation Energy

• Energy that is needed for a chemical reaction to begin

• Once the chemical reaction begins it can continue on its own at a certain rate

• The activation energy generally comes from an increase in temperature

• But, the reaction may be very slow – Concentration of reactants is low

Activation Energy

• Energy that is needed for a chemical reaction to begin

• Once the chemical reaction begins it can continue on its own at a certain rate

• The activation energy generally comes from an increase in temperature

• But, the reaction may be very slow – Concentration of reactants is low– Difficult for the reactant to interact

Catalyst

• Substance that decreases the activation energy needed to start a chemical reaction

Catalyst

• Substance that decreases the activation energy needed to start a chemical reaction

• Also increases the rate of the chemical reaction

Catalyst

• Substance that decreases the activation energy needed to start a chemical reaction

• Also increases the rate of the chemical reaction

• Catalysts take part in reactions, but are not considered part of the reactants or products

Catalyst

• Substance that decreases the activation energy needed to start a chemical reaction

• Also increases the rate of the chemical reaction

• Catalysts take part in reactions, but are not considered part of the reactants or products– This is because the catalyst is neither changed by

the chemical reaction or used up during a chemical reaction

Chemical Reactions In An Organism

• Must take place at an organism’s body temperature

Chemical Reactions In An Organism

• Must take place at an organism’s body temperature– The activation energy cannot come from an

increase in temperature

Chemical Reactions In An Organism

• Must take place at an organism’s body temperature– The activation energy cannot come from an

increase in temperature• Reactants are found in low concentrations

Chemical Reactions In An Organism

• Must take place at an organism’s body temperature– The activation energy cannot come from an

increase in temperature• Reactants are found in low concentrations– Your body is large for a small molecule, finding

another reactant can be difficult

Enzymes

• Catalysts for chemical reactions in living things

Enzymes

• Catalysts for chemical reactions in living things• Lower the activation energy

Enzymes

• Catalysts for chemical reactions in living things• Lower the activation energy• Increase the rate of chemical reactions

Enzymes

• Catalysts for chemical reactions in living things• Lower the activation energy• Increase the rate of chemical reactions• Reactions are reversible

Enzymes

• Catalysts for chemical reactions in living things• Lower the activation energy• Increase the rate of chemical reactions• Reactions are reversible– Therefore do not change the direction of the

reaction

Enzymes

• Catalysts for chemical reactions in living things• Lower the activation energy• Increase the rate of chemical reactions• Reactions are reversible– Therefore do not change the direction of the

reaction– Do not affect chemical equilibrium

Enzymes Are Proteins

• Chains of amino acids

Enzymes Are Proteins

• Chains of amino acids• Enzymes are VERY dependent upon their

structure to function properly

Enzymes Are Proteins

• Chains of amino acids• Enzymes are VERY dependent upon their

structure to function properly• Temperature and pH can affect the shape and

function/activity

Enzymes Are Proteins

• Chains of amino acids• Enzymes are VERY dependent upon their

structure to function properly• Temperature and pH can affect the shape and

function/activity– Generally work best at organisms body temp.

Enzymes Are Proteins

• Chains of amino acids• Enzymes are VERY dependent upon their

structure to function properly• Temperature and pH can affect the shape and

function/activity– Generally work best at organisms body temp.– At higher temps the enzyme breaks apart through

loss of hydrogen bonds, and therefore cannot function

Enzyme Structure Is Function

• Enzymes are specific

Enzyme Structure Is Function

• Enzymes are specific• Shape allows for only specific reactants to

bind to the enzyme

Enzyme Structure Is Function

• Enzymes are specific• Shape allows for only specific reactants to

bind to the enzyme• Substrates: specific reactants for an enzyme

Enzyme Structure Is Function

• Enzymes are specific• Shape allows for only specific reactants to

bind to the enzyme• Substrates: specific reactants for an enzyme– Substrates temporarily bind to enzymes

Enzyme Structure Is Function

• Enzymes are specific• Shape allows for only specific reactants to

bind to the enzyme• Substrates: specific reactants for an enzyme– Substrates temporarily bind to enzymes– Active Site: Binding place of substrate to enzyme

Enzyme Structure Is Function

• Enzymes are specific• Shape allows for only specific reactants to

bind to the enzyme• Substrates: specific reactants for an enzyme– Substrates temporarily bind to enzymes– Active Site: Binding place of substrate to enzyme

Lock And Key Model

• Enzymes bring substrates close to active site

Lock And Key Model

• Enzymes bring substrates close to active site• Decrease activation energy

Lock And Key Model

• Enzymes bring substrates close to active site• Decrease activation energy– Becomes easier to break bonds between

substrates

Lock And Key Model

• Enzymes bring substrates close to active site• Decrease activation energy– Becomes easier to break bonds between

substrates• Allows the joining of the substrates

Lock And Key Model

• Enzymes bring substrates close to active site• Decrease activation energy– Becomes easier to break bonds between

substrates• Allows the joining of the substrates• Then releases the product

Induced Fit Model

• The binding of the substrate changes the shape of both the substrate and the enzyme

Induced Fit Model

• The binding of the substrate changes the shape of both the substrate and the enzyme

• This change in shape allows catalysis to occur

Induced Fit Model

• The binding of the substrate changes the shape of both the substrate and the enzyme

• This change in shape allows catalysis to occur• The induced fit model therefore is an

expansion of the lock and key model

Types of Enzymes

• Named for their reactions…

Types of Enzymes

• Named for their reactions…• Transferase: Move functional group from one

molecule to another

Types of Enzymes

• Named for their reactions…• Transferase: Move functional group from one

molecule to another• Ligase: Combining two molecules

Types of Enzymes

• Named for their reactions…• Transferase: Move functional group from one

molecule to another• Ligase: Combining two molecules• Oxidoreductase: Two reactions, transferring

electrons from one molecules to another

Types of Enzymes

• Named for their reactions…• Transferase: Move functional group from one

molecule to another• Ligase: Combining two molecules• Oxidoreductase: Two reactions, transferring

electrons from one molecules to another– Forward and reverse directions

Types of Enzymes

• Named for their reactions…• Transferase: Move functional group from one

molecule to another• Ligase: Combining two molecules• Oxidoreductase: Two reactions, transferring electrons

from one molecules to another– Forward and reverse directions

• Isomerase: conversion of one molecule into another, without the loss of any molecules(generally a 3-D rearrangement)

Types of Enzymes

• Named for their reactions…• Transferase: Move functional group from one molecule to

another• Ligase: Combining two molecules• Oxidoreductase: Two reactions, transferring electrons from

one molecules to another– Forward and reverse directions

• Isomerase: conversion of one molecule into another, without the loss of any molecules(generally a 3-D rearrangement)

• Hydrolase: Add water to a molecule that breaks it apart into two separate molecules

Types of Enzymes

• Named for their reactions…• Transferase: Move functional group from one molecule to

another• Ligase: Combining two molecules• Oxidoreductase: Two reactions, transferring electrons from

one molecules to another– Forward and reverse directions

• Isomerase: conversion of one molecule into another, without the loss of any molecules(generally a 3-D rearrangement)

• Hydrolase: Add water to a molecule that breaks it apart into two separate molecules

• Lyase: Break a molecule into two parts without the use of water