enzymes 1. proteins contain ______________________________ ______________________________...
TRANSCRIPT
EnzymesEnzymes
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Proteins
•Contain ___________________________________________________________________________________________________bound by ________________bonds•Most also contain sulfur•Some contain small amounts of
phosphorus, iron, and iodine
Role Example
Enzymes control chemical reactions. Hormones regulate many physiologic processes..ex: insulin affects glucose transport into cell
Hemoglobin transports oxygen and carbon dioxide in the blood. Plasma proteins transport many substances in the blood. Proteins in plasma membranes control the movement of materials into and out of the cell
Protection
Actin and myosin in muscle are responsible for muscle contraction
Structure Collagen fibers form a structural framework in many parts of the body. Keratin adds strength to skin, hair, nails
Energy
Roles of Protein
Speed of Rxns• __________________________________________minimum
amount of energy reactants must have to start a rxn• Catalysts- substances that ____________________the rate of
a chemical rxn without being ________________________________________________________________________________________________________________
• Enzymes- _____________________________________________• Increase the rate of rxn by -
__________________________________________________________________________________________________________
• Can increase rate by 1,000,000x
What Are Enzymes?What Are Enzymes?•Most enzymes are ____________________ ____________________ ((tertiary and quaternary structures)•Act as CatalystCatalyst to
accelerates a reaction • ______________________________________________
______________________________________________changed in the process
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EnzymesEnzymes•Are _____________ for what they will catalyzecatalyze•Are ReusableReusable•End in –asease-________________-________________-________________-________________-________________-________________
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How do enzymes Work?How do enzymes Work?
Enzymes work by ________________________________________________________________________________________________________________________________________________
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EnzymesEnzymes
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FreeEnergy
Progress of the reaction
Reactants
Products
Free energy of activationFree energy of activation
Without Enzyme
With Enzyme
How do enzymes work?
• Each enzyme has a unique 3-D shape, including a surface groove called an ________________________________________________
• The enzyme works by binding a specific chemical reactant (_________________________) to its _____________________________, causing the substrate to _________________________________________________________________________________________________________
• The resulting product (s) is then _____________from the active site.
Image: Enzymatic reaction, Jerry Crimson ManniFrom the Virtual Cell Biology Classroom on ScienceProfOnline.com
Enzyme-Substrate ComplexEnzyme-Substrate ComplexThe ________________________(reactant) an ________________________acts on is the ________________________
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EnzymeSubstrate Joins
Active SiteActive Site•A ______________________________________________of an enzymeenzyme molecule which ____________________________________to the substratesubstrate.
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EnzymeSubstrate
Active Site
Induced FitInduced Fit•A change in the ________________________of an enzyme’s active site•________________________________________________________________________________________________
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…are reusable
They are not consumed (used up) in the reactions they catalyze.
Enzymes…Enzymes…
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
The more cans (substrate), the more $ (product).
The more recycling machines (enzymes), the faster the cans turn into $.
Enzymes are like tiny machines within living things.
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
$
$$
$
$
$$
Induced FitInduced Fit• __________________________________________________________________________________________ (H+ and ionic bonds are involved).• InducedInduced by the substratesubstrate..
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Enzyme
Active Sitesubstrate
induced fit
Formats for writing a enzymatic reaction.
( enzyme)
reactant + reactant -----------> product
( enzyme)
Reactant -----------> product + product
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
What Affects Enzyme What Affects Enzyme Activity?Activity?
•Three factors:Three factors:
1. 1.
2. 2.
3. 3.
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1. Environmental 1. Environmental ConditionsConditions
1. Extreme1. Extreme Temperature Temperature are the are the most dangerousmost dangerous
- - ________________________________________________________________________________________________________________________
2.2. ________________________________________(most like 6 (most like 6 - 8 pH near neutral)- 8 pH near neutral)
3.3. ________________________________________________(salt (salt ions)ions)
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How do you stop an enzyme?
Irreversible egg protein
denaturation caused by high
temperature (while cooking
it).
Denature It!
• Alteration of a protein shape through some form of external stress
• Example, by applying heat or changing pH.
•
__________________________________________________________________________________________________. From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Cofactors & Coenzymes
_________________________ substances substances (zinc, iron, copper, vitamins)(zinc, iron, copper, vitamins) are sometimes need for proper enzymatic activity.
• Coenzyme vs Cofactor: What’s the difference?
Cofactor more general term. Includes _______________________and _______________________molecules.
Coenzyme type of cofactor, But specifically ________________________molecules.
Image: Enzyme with Cofactor, Wiki. Ribbon-diagram showing carbonic anhydrase II. The grey sphere is the zinc cofactor in the
active site. From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Coenzyme: Vitamin B12
• Most _____________________are coenzymes essential in helping move atoms between molecules in the formation of carbohydrates, fats, and proteins.
• Exclusively synthesized by ____________________
• Dietary sources include meat, eggs, dairy products and supplements.
Images: Streptomyces spores, Wiki; Vitamin B12 chemical structure, Wiki
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Two Types of Enzyme Two Types of Enzyme InhibitorsInhibitors
1.1. ______________________________________________________
Chemicals that _____________________________________________and _______________with it for the active site.
Reversible depending on concentration of inhibitor and substrate.
Image: Competitive inhibition of enzyme, Jerry Crimson Mann
EXAMPLE: The drug Antabuse is used to help alcoholics quit drinking. Antabuse inhibits aldehyde oxidase, resulting in the accumulation of acetaldehyde (say a-si-’tell-de-hide) during the metabolism of alcohol. Elevated acetaldehyde levels cause symptoms of nausea and vomiting.
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Two Types of Enzyme Two Types of Enzyme InhibitorsInhibitors
2. 2. Non-competitive Non-competitive
InhibitorInhibitor
______________
_______________________
_______________________
_______________________
_______________________
_______________________
_______________________
_______________________
Usually reversible, depending on concentration of inhibitor & substrate. EXAMPLE: You may know that compounds
containing heavy metals such as lead, mercury, copper or silver are poisonous. This is because ions of these metals are non-competitive inhibitors for several enzymes.
Image: Pouring liquid mercury, Bionerd From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Enzyme InhibitorsEnzyme Inhibitors
____________________________________________________________________
Many medications are enzyme inhibitors.
Enzyme inhibitors are also used as
herbicides and pesticides
Images: Prescription bottle, T. Port; Dead cockroach, Wiki
EXAMPLE:
•Another example of competitive inhibition is protease inhibitors.
•They are a class of anti-retroviral drugs used to treat HIV.
•The structure of the drug ritonavir (say ri-TAHN-a-veer) resembles the substrate of HIV protease, an enzyme required for HIV to be made.
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Meet the Enzyme: _______________
____________________________________________________________________________________________________________________________________________
Involved in ___________________ of adenosine triphosphate (ATP), from:
- adenosine diphosphate (ADP)
- a phosphate group and - energy from H+ ion
gradient
ATP is the most commonly used "energy currency" of cells.
Reaction:
(ATP synthase)
ADP + Pi -------ATP substrate substrate product
Images: ATP synthase diagram, Tim VickersFrom the Virtual Cell Biology Classroom on ScienceProfOnline.com
Meet the Enzyme: ______________
• Catecholase is present in most fruits and vegetables
• It is the enzyme that facilitates the browning of cut or bruised fruits and vegetables by catalyzing the following reaction:
catecholase _____________+ _____________----------------- ________ colorless substrate brown product
Image: Bananas T. PortFrom the Virtual Cell Biology Classroom on ScienceProfOnline.com
Meet the Enzyme: Catecholase
Lemon juice and other acids are used to preserve color in fruit, particularly apples, by lowering the pH and removing the copper (cofactor) necessary for the enzyme to function.
Reaction: catecholase
catechol + O2 ---------- polyphenol colorless substrate brown product
Images: Apples, T. Port; Lemons, André Karwath; Enzyme with Cofactor, Wiki; pH scale, Edward Stevens, Wiki
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Meet the Enzyme: ________________• Pineapple contains enzyme bromelain,
which can digest protein
• Jell-O® is made of gelatin, a processed version of a structural protein called collagen 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 Jell-O® .
b. The other, fresh pineapple was used.
Q: Why is one Jell-O solid and the other liquid?
Image: Pineapple, Whaldener Endo
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Meet the Enzyme: ___________________
(bromelain)
____________+ _____ -------------- _________ substrate products
Bromelain is a __________________ enzyme that facilitates hydrolysis of protein.
Remember, hydrolysis cuts molecule by adding water…the reverse of the hydration synthesis pictured to the left.
FYI: Bromelain is used as a meat tenderizer. Breaks down the collagen in meat. So what do you think could happen to your tongue when you eat fresh pineapple?
From the Virtual Cell Biology Classroom on ScienceProfOnline.com