Transcript What Are Enzymes?

Section 2.5
Key Concept:
Enzymes lower the activation
energy for chemical reactions in
living things
What Are Enzymes?
• Enzymes are a
special group of
protein molecules
which speed up
chemical rxns in
living cells by
lowering the
activation energy
(EA)
Fun Facts about Enzymes
• Make rxns go 10 trillion
times faster –
1500 yrs vs. 5 seconds
• Are not living
• Are reusable
• There are about 2000
different enzymes in each
one of your cells
• Names usually end in -ase
How do enzymes work?
• Each enzyme has a unique 3-D shape, including a surface groove
called an ACTIVE SITE.
• One or more molecules called SUBSTRATES chemically bond to
the enzyme’s active site.
• When joined they are called an ENZYME-SUBSTRATE COMPLEX
• Changes in how the atoms are bonded occur resulting in new
molecules being made called PRODUCTS .
• Products are then released from the active site.
How enzymes make rxns go faster
Enzymes work by
reducing the amount
of energy needed
(EA) for the bonds
in the substrate
molecules to break
Enzyme-Substrate Complex
The reactant an
enzyme acts on is
specifically called
the _________.
Substrate
Joins
Enzyme
______ _____
• A specific region of an enzyme molecule which binds
to the substrate.
Active
Site
Substrate
Enzyme
EnzymeAnimation : Gary E. Kaiser http://student.ccbcmd.edu/biotutorials/proteins/enzsub.html
View : http://highered.mcgraw-
hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html
An enzyme flick
Let the show begin....
General Types of Enzymes
• Amylases –
break starch to glucose
• Proteases –
• break proteins to
amino acids
• Lipases –
break lipids to fatty
acids and glycerol
• Nucleases – break
nucleic acids DNA
and RNA to
nucleotides
Shape of a Protein
• An enzyme fits
with its specific
substrate like a
“lock and key”
How Do You Stop an Energizer Enzyme?
DENATURE IT!
Means it loses its 3D shape
4 levels of Protein Structure
Factors Affecting Enzyme Activity
• Temperature
• pH
• Cofactors & Coenzymes
• Inhibitors
Temperature & pH
• Enzymes work best at specific temperatures
• This is why very high fevers are so dangerous.
They can cook the body’s proteins
• Enzymes usually work best between pH 6 - 8
Coenzymes & Cofactors
• Molecules that
are needed by the
enzyme to work
properly.
• Many are
vitamins and
mineral
substances (zinc,
iron, copper,
vitamins)
Image:
EnzymeCofactor : Public domain Wiki, Ribbon-diagram showing carbonic anhydrase II. The grey
sphere is the zinc cofactor in the active site.
Diseases due to enzyme
damaged or missing
• Lactose intolerance
• Lacking lactase
Phenylketonuria
Phenylalanine hydroxylase
Enzyme Inhibitors
Chemicals that resemble an enzyme’s normal
substrate and compete with it for the
active site.
Substrate
Competitive inhibitor
Enzyme
1. Competitive inhibitors:
Resemble an enzyme’s normal substrate and compete
with it for the active site.
Image: Competitive Inhibition : wwwbiol.paisley.ac.uk/.../chapter3_2.html
Inhibitors can also attach to another
part of the enzyme causing the enzyme
to change the shape of its active site.
If its shape changes..it no longer works!
Enzyme
Substrate
active site
altered
Noncompetitive
Inhibitor
Enzyme Inhibitors
Blocking an
bacteria’s enzymes
can kill it
Many antibiotic
drugs are enzyme
inhibitors.
Enzyme inhibitors
are also used as
weed and bug killers
Images
Dead Bug : www.kansas.gov/help_center/user_testing.html
Prescription Drugs : www.patentdocs.us/.../08/by-kevin-enoon.html
Enzymes are ____ ________ in the reactions they catalyze.
Think of them as tiny machines in manufacturing.
The more machines, the faster the accumulation of _________.
Image:
Wine Bottling : www.morrison-chs.com/timingscrews/index.html
Wine Vats: www.lymebaywinery.co.uk/pages/about_us.htm
Formats for writing a chemical reaction.
( ________ )
_______ + ________ -----------> _________
( ________ )
__________ -----------> ________ ________
Coenzyme : Vitamin B12
• Example:
Most _________ are
coenzymes essential in
helping move atoms between
molecules in the formation of
carbohydrates, fats, and
proteins.
• Exclusively synthesized by
___________ (found
primarily in meat, eggs and
dairy products).
Image: VitaminB12 : NIH, Public Domain
www.nlm.nih.gov/.../ency/imagepages/19516.htm
Featured Enzyme #1: Catecholase
• Catecholase is present in most ______ and __________.
• It is the enzyme that facilitates the ________ of cut or
bruised fruits and vegetables by catalyzing the following
reaction:
(______________)
_________ + _____ ----------------- _____________
colorless substrate
brown product
Featured Enzyme #1:
Catecholase
& Noncompetetive Inhibition
_________ juice and other acids are
used to preserve color in fruit,
particularly apples, by lowering the ____
and removing the copper site (cofactor)
necessary for the enzyme to function.
catechol
colorless substrate
+ O2
catecholase
--------------------------
polyphenol
brown product
Featured enzyme #2: Bromelain
•
Pineapple contains enzyme bromelain, which can
_______ _________.
•
Jell-O is made of gelatin, a processed version of a
structural protein called _________ that is found in
many animals, including humans.
•
Collagen big, fibrous molecule makes skin, bones, and
tendons both strong and elastic.
•
Gelatin you eat in Jell-O comes from the collagen in
cow or pig bones, hooves, and connective tissues.
(Yummie!)
•
Examine 2 containers:
a. In one, canned pineapple was used to make jello.
b. The other, fresh pineapple was used.
http://www.thinkbank.com/iwb/flash/enzymetale.
html