EnzymesEnzymesProtein molecules that act as Protein molecules that act as catalystscatalysts

CatalystsCatalysts Speed up the rate of reactionsSpeed up the rate of reactions Are not permanently changed or used upAre not permanently changed or used up Reactants: what the catalysts changeReactants: what the catalysts change

To the right is a Scanning To the right is a Scanning Electron Microscope image of Electron Microscope image of rutile crystals grown using rutile crystals grown using Altair's process.Altair's process.

Jobs enzymes doJobs enzymes do Join monomers to make polymersJoin monomers to make polymers Break down polymersBreak down polymers Phosphorylate moleculesPhosphorylate molecules Bring atoms together so they can trade electronsBring atoms together so they can trade electrons

What kind of bonding is this?What kind of bonding is this?

polypropylene can be widely polypropylene can be widely found in items such as plastic found in items such as plastic bottles and boxes, dishwasher-bottles and boxes, dishwasher-safe food containers, patio safe food containers, patio furniture, rope, upholstery, furniture, rope, upholstery, diapers, and carpeting. diapers, and carpeting.

It did not become commercially It did not become commercially viable until a catalyst that viable until a catalyst that increased its production could increased its production could be foundbe found

Naming enzymesNaming enzymes

Depends on Depends on substrates and substrates and kinds of reactionskinds of reactions

Nearly all enzymes Nearly all enzymes end in “Ase”end in “Ase”

Polycarbonate Polycarbonate seen under a seen under a microscopemicroscope

Activation energyActivation energy

Adding energy to a substance makes it Adding energy to a substance makes it more reactivemore reactive

For different reactions different energy For different reactions different energy thresholds are neededthresholds are needed

Enzymes lower that thresholdEnzymes lower that threshold

Enzyme Enzyme substrate substrate complexescomplexes

Functional groups Functional groups determine an determine an enzyme’s shapeenzyme’s shape

The part the The part the substrate binds to substrate binds to is the active siteis the active site It looks like a It looks like a

pocket or groovepocket or groove This means that an This means that an

enzyme is very enzyme is very specificspecific

Helper moleculesHelper molecules

Some enzymes need to contain an Some enzymes need to contain an additional molecule or ion to do their jobadditional molecule or ion to do their job

Cofactors are helpers held on by ionic or Cofactors are helpers held on by ionic or other kinds of bondsother kinds of bonds

Coenzymes are non-protein organic Coenzymes are non-protein organic moleculesmolecules Like vitaminsLike vitamins They don’t get used up so we don’t need too They don’t get used up so we don’t need too

manymany

Factors that effect Factors that effect enzyme activityenzyme activity VVmaxmax this is the fastest number of substrates an this is the fastest number of substrates an

enzyme can processenzyme can process Competitive inhibitors: look like the enzymes Competitive inhibitors: look like the enzymes

substrate so they block up the active sitesubstrate so they block up the active site More substrate can reduce their effectsMore substrate can reduce their effects

competitive inhibition

inhibitorsubstrate

Factors that effect Factors that effect enzyme activityenzyme activity Noncompetitive inhibitors: effects don’t reverseNoncompetitive inhibitors: effects don’t reverse

Cyanide, prevents Iron from doing its job in breathingCyanide, prevents Iron from doing its job in breathing That’s why its fatalThat’s why its fatal

non-competitive inhibition

inhibitorsubstrate

Allosteric enzymesAllosteric enzymes

Have 2 or more binding sitesHave 2 or more binding sites Binding to a regulatory site changes the Binding to a regulatory site changes the

shape of the inactive enzyme, either shape of the inactive enzyme, either stimulating or inhibiting enzymatic reaction stimulating or inhibiting enzymatic reaction

from Drug Discovery Today11 481-493 (2006)

“statins”Inhibitors of the enzyme HMG CoA reductaseThe first enzyme in the pathway that makes cholesterol

Metabolic syndromeMetabolic syndrome

a combination of medical disorders that increase one's risk for cardiovascular disease and diabetes.

Leads to1. Obesity, particularly around the waist (having an "apple shape")

2. Elevated blood pressure

3. An elevated level of triglycerides and a low level of high-density lipoprotein (HDL) — the "good" cholesterol

4. Resistance to insulin

Complex interplay between Complex interplay between glucose/fat/cholesterol glucose/fat/cholesterol metabolismmetabolism

Enzymes?Enzymes?

Biological washing powdersBiological washing powdersDrug targetsDrug targetsTests for disease/test kitsTests for disease/test kitsClinical tests for liver damageClinical tests for liver damage

Biological washing Biological washing powderspowders

Contain lipases and proteases to digest fat and protein in stainsWork at lower temperatures

Energy and Enzymes

Almost all energy for life is derived from the sun.

Life requires energy.

A “factoid” -

The sun’s energy that strikes Earth each day is equivalent to one million Hiroshima-sized atomic bombs.

Photosynthesis harnesses about 1% of that energy – 10,000 “atomic bomb equivalents” per day.

Chemistry and Life

One unromantic but productive way of viewing life is to see it as a set of coordinated chemical reactions.

This leads to an obvious question – What determines what chemical reactions are possible?

Chemical Reactions

Whether a chemical reaction will or won’t occur under particular conditions is determined by the laws of thermodynamics.

If the overall amount of order is decreased by a reaction, the reaction is favored.

Keeping it simple -

Generally, if energy is released in a reaction, the reaction is favored.

The Direction of Spontaneous Reactions (and what it takes to go the other way)

Life Requires Lots of Unfavorable Reactions – How Is This Possible?

By coupling favorable to unfavorable reactions.

favorable reactions

unfavorable reactions

The “Nature of Life” – Coupling Favorable to Unfavorable Reactions

ATP - Life’s Energy Currency

Energy is released when ATP is hydrolyzed (broken down) to ADP.

ATP is restored from ADP and an input of energy.

ATP’s energy is used to drive endergonic (energy-requiring) reactions.

The Way ATP Often Works

Enzymes Speed Biochemical Reactions

Enzymes are biological catalysts – substances that speed a reaction without being altered in the reaction.

Most enzymes are proteins, some are RNA.

Enzymes are essential for life.

Model of the surface of an enzyme.

Enzymes Lower a Reaction’s Activation Energy

Enzyme Action

The Fit Between Enzyme and Substrate is Critical and Precise

Hexokinase, an enzyme (blue), binding its substrate, glucose (yellow).

The active site of an enzyme is where substrate is bound.

Many Enzymes Work by Altering the Shape of Their Substrates

Enzyme Deficiency and Health

Most genetic disorders are due to a deficiency in enzyme function.

This archival photo shows three children with the enzyme deficiency that causes phenylketonuria.

The synthesis of biological molecules often requires many enzyme-catalyzed steps.

The entire set of steps is a metabolic pathway.

Metabolic Pathways

Metabolic Pathways

The metabolic pathway that produces tryptophan – an amino acid. This is one of hundreds of metabolic pathways essential for life.

Enzyme Activity is Often Regulated

Feedback inhibition - a common form of enzyme regulation in which the product inhibits the enzyme .