FCH - Enzymes Flashcards
Break the chemical bonds in reactants and re-arrange these bonds into products.
Chemical Reactions
Absorb of Energy
Endothermic
Release of Energy
Exothermic
The minimum energy required for a chemical reaction to take place.
Activation Energy
Chemical reactions can be speed up at least two ways:
- Temperature
- Catalysts
Speeds up the rate of chemical reactions.
Catalysts
Catalysts can either be _____ or _____.
Organic or Inorganic
Catalyst that is metals or ionic compounds.
Inorganic catalyst
Organic catalysts or ______.
Enzymes
Characteristics of Organic catalysts: Enzymes.
- Enzymes are natural and non-toxic.
- Due to its high-specificity enzymes have no side reactions; thus, products of enzymatic process possess no contaminants.
- Enzymes are active under mild conditions of temperature and pH; and
- Enzymes can be easily inactivated.
Enzymes as biocatalysts possess three important traits:
- They are proteins.
- They are catalysts.
- They exhibit selectivity towards substrates.
The most common and ubiquitous form of biological catalyst.
Enzymes
They are responsible for life processes and mediate synthetic, turnover, signalling, and metabolic functions.
Enzymes
Enzyme History
Egyptian and Sumerians developed fermentation for use in brewing, bread making and cheese making.
2000 BC
Enzyme History
Calves’ stomach and the enzyme chymosin used for cheese making.
800 BC
Enzyme History
Yeast cells which cause fermentation were identified and the term ‘enzyme’ has first named meaning in yeast in Greek.
1878
Enzyme History
Enzymes were shown to be protein.
1926
Enzymes history
Enyzme preparation was developed to improved the digestibility and nutrient availability for animal feed.
1980
They are present in raw materials and are responsible for the continuous chemical changes that occur in food products.
Enzymes
As mentioned enzymes are present in raw materials and are responsible for the continuous chemical changes that occur in food products. Give three examples.
- Can be suppressed (e.g. sterilizing),
- Led in the right direction (cheese making)
- Added (exogenous enzymes).
In food systems, enzymes serve as:
- to upgrade product quality,
- to develop flavors,
- improve extraction technique
- increase by-product utilization.
TWO classification of enzymes.
- Exogenous
- Endogenous
This classification of enzymes is added to foods to cause a desirable change.
Exogenous
This classification of enzymes can be obtained from a variety of sources.
Exogenous
This classification of enzymes choices are based on cost and functionality.
Exogenous
What are the appropriate functionality of EXOGENOUS enzymes?
- Catalytic activity
- Selectivity
- Stability under the conditions that prevail during the specific application.
This classification of enzymes exist in foods which may or may not be responsible for reactions that affect food quality.
Endogenous
This classification of enzymes pose greater challenges to control, since they are present in the food matrix at a range of levels.
Endogenous
This classification of enzymes are constraints as to how the foodstuff can be handled to modulate enzyme action.
Endogenous
What are the source of enzymes?
- Edible plants
- Animals
- Microorganisms
As a source of enzymes, it is the most utilized due to its increased stability and versatility.
Microorganisms
Microorganism should not pose this characteristics as a source of enzymes:
- It should not be pathogenic.
- It should not produce toxin.
- It should not produce antibiotics that can destroy the enzyme
They are the agents that accelerate the rate of reactions without themselves undergoing any net chemical modification.
Catalysts
They function similarly by reducing the energy barrier required for the
transformation of a reactant into a product.
Catalysts
Mechanism of Enzyme Action
These are the molecule that binds to the active site of the enzyme.
Substrates
Mechanism of Enzyme Action
This is the specific region or location of the enzyme which combines with the substrate.
Active site
Mechanism of Enzyme Action
In this model, the enzyme-substrate interaction suggests that the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another.
Lock-and-key model
Mechanism of Enzyme Action
Like a key into a lock, only the correct size and shape of the substrate (the key) would fit into the active site (the keyhole) of the enzyme (the lock).
Lock-and-key model
Mechanism of Enzyme Action
This model suggests that the active site continues to change until the substrate is completely bound to the active site of the enzyme, at which point the final shape and charge is determined.
Induced-fit model
Mechanism of Enzyme Action
Unlike the lock-and-key model, the __________ shows that enzymes are rather flexible structures.
Induced-fit model
Is the protein part of the enzyme and in most cases inactive or possess no catalytic activity.
Apoenzyme
It contains contains a protein part plus a prosthetic group and the active form of the enzyme.
Holoenzyme
Are compounds that are indispensable to enzyme action.
Prosthetic group
What are the Prosthetic group?
- Coenzyme
- Cofactor
- Ligands
Prosthetic group:
The vitamin derived and in most cases water soluble vitamins.
Coenzyme
Prosthetic group:
Metals and Minerals
Cofactor
Prosthetic group:
Biomolecules such CHO or lipids attached to the protein part of the enzyme.
Ligands
Is a group of enzymes that catalyzes a single reaction only. They are multiple in forms and differs in amino acid sequence.
Isozymes
Is the part of the enzyme where the chemical reaction occurs. This is also the binding site of the substrate.
Active site
These are substances that can either activate or inhibit the enzyme by altering the conformation of the active site.
Allosteric factor
Is the study of the rate of enzyme-catalyzed reactions.
Enzyme Kinetics
The transitory of molecular structure in which the molecule is no longer a substrate but not yet a product.
Transition state
Is the amount of energy needed to bring 1 mole of the reactants to the transition state.
Activation energy
What are the 6 groups of enzyme classification and nomenclature?
- Oxidoreductases (EC 1)
- Transferases (EC 2)
- Hydrolases (EC 3)
- Lyases (EC 4)
- Isomerases (EC 5)
- Ligases (EC 6)
It catalyze oxidation reduction reactions.
Oxidoreductases
Examples of Oxidoreductases
- Polyphenoloxidase
- Catalase
- Peroxidase
- Lipoxygenase
- Glucose oxidase
It catalyze reactions involving transfer of functional groups.
Transferases
Examples of Transferases
- Cyclodestrin glycosyltransferase
It catalyze hydrolytic reactions.
Hydrolases
Three kinds of Hydrolases are:
- Peptide-hydrolases: proteolytic enzymes (e.g. papain).
- Glycoside-hydrolases: amylolytic enzymes, cellulases, hemicellulases, invertase.
- Ester-hydrolases: pectin-esterase, lipase, chlorophylase, ribonucleas.
It catalyze reactions involving addition of double bonds.
Lyases
Examples of Lyases
- Endo-pectate lyase,
- Endo-pectin lyase
It catalyze isomerization reactions.
Isomerases
Example of Isomerases
- Glucose isomerase
It catalyze formation of bonds involving the use of ATP.
Ligases
Most restrictive type of specificity. The enzyme will catalyze only one reaction with a specific substrate.
Absolute specificity
Example of Absolute specificity
urease acts only urea; maltase acts only to maltose
The enzyme will act only on molecules that have specific functional groups.
Group specificity
Example of Group specificity
Chymotrypsin – specific on peptide bonds where aromatic groups are attached; trypsin specific only to peptide bonds where basic amino acids are attached.
The enzyme will act on a particular type
of chemical bond regardless of the rest of the molecular structure.
Linkage specificity
Example of Linkage specificity
lipase – acts on an ester bond
The enzyme will act on a
particular steric or optical isomer.
Stereochemical specificity
Example of Stereochemical specificity
amylase – specific for alpha-linkages
What are the 5 enzyme activity and inhibition?
- Temperature
- pH
- Substrate concentration
- Enzyme concentration
- Enzyme inhibitors
Temperature
Generally most enzymes have optimum temperature at 30 to 40 °C. At higher temperature, activity decreases due to protein denaturation.
pH
The optimum pH of most food enzymes occurs at a range of 4.5 – 8.0. At extreme pH enzyme is inactivated due to denaturation. However, some enzymes are active at acidic pH such as stomach enzyme pepsin.
Arginase is most active at a basic pH 10.
Substrate concentration
At lower concentrations, the active sites on most of the enzyme molecules are not filled because there is not much substrate. The maximum velocity of a reaction is reached when the active sites are almost continuously filled. After this point, reaction rate will not increase.
Enzyme concentration
As the amount of enzyme is increased the rate of reaction increases. If there are more enzyme molecules than are needed, adding additional enzyme will not increase the rate. Reaction rate therefore increases as enzyme concentration increases but then it levels off.
Enzyme inhibitors
Enzyme inhibitors are substances which alter the catalytic action of the enzyme and consequently slow down, or in some cases, stop catalysis. There are three common types of enzyme inhibition - competitive, non-competitive and substrate inhibition.
The enzyme production and use of enzymes is a major part of ____________ industry.
Biotechnology
The first enzyme produced in 1896 which is a fungal amylase used to cure digestive disorders.
Taka- Diastase
Sources of enzymes in plants.
- Bromelain
- Esterase
- Ficin
Sources of Enzymes in animals.
- Lipase
- Pepsin
- Rennin
Challenges of using plants and animals as source of enzymes.
- High cost
- Difficult to isolate and purify
- High risk
The most significant and convenient source of commercial enzymes used in the industry.
Microorganisms
This source of enzyme in microorganisms can produce at least 40 commercial enzymes.
Aspergillus Niger
What are the 4 steps in microbial production of enzyme?
- Selection of organism
- Formulation of Medium
- Production Process - Fermentation
- Recovery and Purification
In the first step of microbial production of enzyme, selection or organism should be:
- Non-pathogenic cell
- Less fermentation time
- Simple isolation and separation
In the second step of microbial production of enzyme, formulation of medium should:
- Supports the growth of m/o
- Medium should be readily available, low cost and nutritionally safe
Examples of media that can be used in formulation of medium.
- starch hydrolysate
- molasses
- whey
- casein
- yeast extract
- soybean meal
- wheat
- peanut
- corn syrup liquor
What are the 2 fermentation in the third step of microbial production of enzyme which is the production process?
- Submerged culture fermentation (SCF)
- Solid state fermentation (SSF)
It is commonly used for industrial application for microbes that require high MC.
Submerged culture fermentation (SCF)
It gives more yield and less chances of infection, and also employs liquid substrate such as broth and molasses.
Production process – Fermentation
It is used for microbes that require less moisture content for growth. Specifically, for isolation of enzymes from fungi.
Solid state fermentation (SSF)
The substrates used for this one include bran, bagasse, and paper pulp.
Solid state fermentation (SSF)
It is less effluent and waste materials can be recycled.
Solid state fermentation (SSF)
In the third step of microbial production of enzyme, production process -fermentation:
- 2- 7 days
- Bioreactor should be sterile throughout the fermentation
- pH, temperature, oxygen supply and nutrient addition must be optimal
- Batch or continuous
In the fourth step of microbial production of enzyme, recovery and purification:
- Depend on the nature of enzyme (crude/ purified, liquid, solid).
- Isolated enzymes can be precipitated using salts and organic solvents.
- Separation and purification of enzymes can be done by chromatographic techniques.
Defined as the imprisonment of cell or enzyme in a distinct support or matrix.
Enzyme Immobilization
The first immobilized enzyme was ________________ of Aspergillus oryzae for the production L-amino acids in Japan.
Amino acylase
Enzyme Immobilization
- Enzymes movement are physically/chemically restricted.
- Even in small amounts, enzymes achieve high biocatalytic activity.
- Immobilized enzymes are also economical because they can also be used repeatedly and continuously.
- The product can be obtained free of the enzyme; thus, of high purity.
Why immobilize enzymes?
- Accelerate the reaction
- Specificity and unmodified
- Cost-effective
- Easy to separate
- Can be re-used
ADVANTAGES OF IMMOBILIZED ENZYMES
- Increased functional efficiency
- Enhanced reproducibility
- Reuse of enzymes
- Continuous use
- Less labor input
- Saes capital const and Investment of the process
- Minimum reaction time
- Less contamination in products
- More stability of products
- Stable supply of products
- Improved process control
- High E:S (enzyme:substrate) ratio
DISADVANTAGES OF IMMOBILIZED ENZYMES
- High cost for the isolation, purification and recovery of active enzyme.
- Applications are limited – very few industries use immobilized enzymes.
- Catalytic process are reduced and completely lost after immobilization.
- Some enzymes become unstable after immobilization.
- Enzymes are inactivated by the heat generated in the system.
APPLICATION OF IMMOBILIZED ENZYMES
- Industrial Production
- Biomedical Applications
- Food Industry
- Research
- Production of biodiesel
- Waste water management
- Textile
- Detergent
It holds the enzyme permanently or temporarily for a period of time. It also should be cheap and easily available.
Support or Matrix
Characteristics of ideal matrix should be:
- Economical
- Chemically inert
- Stable
- Natural / Synthetic
- Organic/ Inorganic
- Enhance enzyme stability
- Regenerable
Support of Matrix: Organic
- Cellulose
- Dextrans
- Agar
- Agarose
- Chitin and chitosan
- Alginate
- Collagen
- Polyacrylate
- Polystyrene
Support of Matrix: Inorganic
- Zeolites
- Ceramics
- Silica
- Glass
- Activated carbon
- Metals
- Charcoal
METHODS OF ENZYME IMMOBILIZATION
- Binding > Adsorption > Covalent
- Physical Retention > Entrapment > Encapsulation
In this method of enzyme immobilization, there is a direct physical and/or chemical interaction between the carrier and enzyme.
Immobilization by binding
In Immobilization by binding, the binding of enzymes to carriers is achieved via _____________ or _________________.
adsorption
covalent mechanisms
The binding on the surface of the
carrier. It is also the oldest and simplest method of enzyme immobilization.
Adsorption
In this method of enzyme immobilization, there is no permanent bond formation between matrix and enzyme and it involves weak forces such hydrogen binding and Van der Waals interaction
Adsorption
Adsorption matrices involves:
silica, charcoal, and clay
It affects the binding in adsorption.
Change in pH, temperature and ionic strength.
The binding is through sharing of electrons between the carrier and the enzyme.
Covalent
It is a permanent method for enzyme immobilization and provides stronger bonds than adsorption.
Covalent
The active enzyme is covalently bonded with a linking agent.
Crosslinking
Functional groups that forms covalent bonds:
- Amino group
- Hydroxyl group
- Carboxyl group
- Phenol rings
- Thiol and methyl thiol groups
Immobilization of enzymes is done through matrix entrapment or membrane closures.
Immobilization by physical retention
In this enzyme immobilization, enzyme is
entrapped in a gel matrix.
Matrix entrapment
Matrix entrapment
Substrate is passed through a column filled with _______ and the end result is the product.
Beads
Matrix entrapment
Enzymes are supported on ________ format made up of collagen, cellulose etc.
Fiber
It is a fast method of enzyme immobilization.
Matrix entrapment
In this enzyme immobilization, enzymes can move in a well-defined space but is limited.
Membrane enclosures
It is the formation of a polymer around
the enzyme.
Encapsulation
It is cheap and simple method of enzyme immobilization and has membrane reactors.
Membrane enclosures
Significance of Enzymes in the Food Industry:
*Produce high quality products
*Low production cost
*Minimal waste
*Minimum energy consumption
*Biodegradability
Enzyme are used in the baking industry for:
*Dough handling
*Taste
*Color
*Moisture and volume
*Control of overcrumb texture
In the baking industry, α-AMYLASE:
- Produce dextrins which are broken down into sugars
- Flour supplement
- Anti-staling effect
- Modifies starch while most starch start to gelatinize
- Starch granules more flexible during storage
In the baking industry, β-AMYLASE:
- Improves yeast fermentation
- Increases bread volume
In the baking industry, MALTOGENIC AMYLASE:
- Breaks down starch into maltose
- Flour supplement
- Anti-staling effect
- Modifies starch while most starch start to gelatinize
- Starch granules more flexible during storage
In the baking industry, LIPOXYGENASE:
Used for bread whitening
In the baking industry, HEMICELLULASE:
- Improves dough property
- Decrease stickiness of bread
In the baking industry, PENTONASES:
- Improves dough machinability – more stable, flexible and easy to handle dough.
- Better storage properties
- Softer crumb
- Improves volume
In the baking industry, PROTEASE AND PROTEINASE:
- Reduces gluten elasticity in biscuits and wafer production
- Improves elasticity
- Improves volume
In the baking industry, GLUCOSE OXIDASE:
- Oxidizes glucose and produce gluconic acid and hydrogen peroxide.
- Strengthens cross-links in gluten
In the dairy industry, RENNIN (RENNET):
- Extracted from the stomach of young calves
- Coagulant of milk to become cheese
- Separates solid curd and liquid whey
- The common vegetable rennet is “thistle”
In the dairy industry, LACTASE:
- Artificially extracted from yeast.
- Used in the production of lactose free milk, ice cream, sweetened flavored and condensed milk.
In the dairy industry, CATALASE:
- Produced from bovine livers and microbial source.
- Prevent oxidation – breaks down hydrogen peroxide.
In the dairy industry, PROTEASE:
- Hydrolyzes specific peptide bond to generate casein in the production of cheese.
- Used to develop flavor compounds.
In the dairy industry, LIPASES:
- Flavor development – increase sweetness
- Prevent crystallization
- Fat hydrolysis
In the dairy industry, PROTEASE:
- Useful during the malting process
- Breaks larger protein which enhances the retention of beer
- Reduces haze
In the brewing industry, β- GLUCANASE:
- Aids in filtration after mashing and brewing
- Breaks down glycosidic bonds within beta-glucan
- Improves clarification
- Reduces maturation duration
In the brewing industry, α- AMYLASE:
- Converts starch dextrin
- Solubilized carbohydrates found in barley and other cereals
- Decreases the time required for mashing
In the brewing industry, AMYLOGLUCOSIDASE:
- Caramelization of saccharides
- Not thermostable
- Results in product loss and increase in impurities
In the meat industry, PROTEASE:
- Bromelain (pineapple), papain (papaya)
- Immobilized from Bacillus spp with alginate gel as the matix
(entrapment method)
In the meat industry, PAPAIN:
- Found in papaya – latex part
- Purified and sold in powder or liquid form
- 95% of meat tenderizer are made from papain
In the meat industry, TRANSGLUTAMINASE:
- Induce gelation in meat products
In the sugar industry, GLUCOSE ISOMERASE:
- Converts glucose to high fructose corn syrup – sweeter
- Can come from different source: bacteria, fungi, animal and plant
- HFCS is a sweetening agent used for carbonated beverage (softdrinks)
In the sugar industry, AMYLOSE AND AMYLOPECTIN:
- Mixture
- Converts starch into glucose
In the sugar industry, β-AMYLASE AND POLLULANASE:
- Used to produce maltose syrup
In the beverage industry, enzymes are used for:
➢ Clarification of juice
➢ Decreases the processing capacity
➢ Enhances color, flavor and texture
➢ Increase juice production, volume and color extraction
➢ Ripening
In the beverage industry, PECTINASE:
- Breaks down pectin and methanol – which is hazardous in high amounts
- Prevents pectin from forming haze to get clear solution
- Used for extraction of color and juice from fresh fruit
- Increase yield
In the beverage industry, β-GLUCANASE:
- Improves clarification and filtration
- Reduces maturation duration
In the beverage industry, CELLULASE AND HEMICELLULASE:
- Breaks down the cell wall of tea leaves and coffee cherry
- Provide excellent fermentation process
- Remove biopolymer and enhance the appearance of coffee and tea.
Responsible for the browning reactions of cut fruits.
Phenolase
Important in juice clarification.
Pectinase
Used as meat tenderizer, partially hydrolyzes collagen and elastin.
Proteinase
An endoenzyme, cleaves glycosidic bonds inside the starch molecule, decreasing its viscosity.
Alpha-amylase
Is a saccharifying enzyme, increasing sweetness by cleaving glycosidic bonds outside the starch molecule.
Beta-amylase
Used for bleaching flour; may destroy carotenol and vitamins; and results to off odor and off flavor in soy products.
Lipoxygenase
Catalyze oxidation of glucose preventing maillard browning.
Glucose oxidase
Converts sucrose to fructose and glucose; prevents crystallization of sugar in jams.
Invertase
Converts glucose to fructose, important in producing high fructose syrup.
Glucose isomerase
