FCH - Enzymes Flashcards
(166 cards)
1
Q
Break the chemical bonds in reactants and re-arrange these bonds into products.
A
Chemical Reactions
2
Q
Absorb of Energy
A
Endothermic
3
Q
Release of Energy
A
Exothermic
4
Q
The minimum energy required for a chemical reaction to take place.
A
Activation Energy
5
Q
Chemical reactions can be speed up at least two ways:
A
- Temperature
- Catalysts
6
Q
Speeds up the rate of chemical reactions.
A
Catalysts
7
Q
Catalysts can either be _____ or _____.
A
Organic or Inorganic
8
Q
Catalyst that is metals or ionic compounds.
A
Inorganic catalyst
9
Q
Organic catalysts or ______.
A
Enzymes
10
Q
Characteristics of Organic catalysts: Enzymes.
A
- 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.
11
Q
Enzymes as biocatalysts possess three important traits:
A
- They are proteins.
- They are catalysts.
- They exhibit selectivity towards substrates.
12
Q
The most common and ubiquitous form of biological catalyst.
A
Enzymes
13
Q
They are responsible for life processes and mediate synthetic, turnover, signalling, and metabolic functions.
A
Enzymes
14
Q
Enzyme History
Egyptian and Sumerians developed fermentation for use in brewing, bread making and cheese making.
A
2000 BC
15
Q
Enzyme History
Calves’ stomach and the enzyme chymosin used for cheese making.
A
800 BC
16
Q
Enzyme History
Yeast cells which cause fermentation were identified and the term ‘enzyme’ has first named meaning in yeast in Greek.
A
1878
17
Q
Enzyme History
Enzymes were shown to be protein.
A
1926
18
Q
Enzymes history
Enyzme preparation was developed to improved the digestibility and nutrient availability for animal feed.
A
1980
19
Q
They are present in raw materials and are responsible for the continuous chemical changes that occur in food products.
A
Enzymes
20
Q
As mentioned enzymes are present in raw materials and are responsible for the continuous chemical changes that occur in food products. Give three examples.
A
- Can be suppressed (e.g. sterilizing),
- Led in the right direction (cheese making)
- Added (exogenous enzymes).
21
Q
In food systems, enzymes serve as:
A
- to upgrade product quality,
- to develop flavors,
- improve extraction technique
- increase by-product utilization.
22
Q
TWO classification of enzymes.
A
- Exogenous
- Endogenous
23
Q
This classification of enzymes is added to foods to cause a desirable change.
A
Exogenous
24
Q
This classification of enzymes can be obtained from a variety of sources.
A
Exogenous
25
This classification of enzymes choices are based on cost and functionality.
Exogenous
26
What are the appropriate functionality of EXOGENOUS enzymes?
1. Catalytic activity
2. Selectivity
3. Stability under the conditions that prevail during the specific application.
27
This classification of enzymes exist in foods which may or may not be responsible for reactions that affect food quality.
Endogenous
28
This classification of enzymes pose greater challenges to control, since they are present in the food matrix at a range of levels.
Endogenous
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This classification of enzymes are constraints as to how the foodstuff can be handled to modulate enzyme action.
Endogenous
30
What are the source of enzymes?
1. Edible plants
2. Animals
3. Microorganisms
31
As a source of enzymes, it is the most utilized due to its increased stability and versatility.
Microorganisms
32
Microorganism should not pose this characteristics as a source of enzymes:
1. It should not be pathogenic.
2. It should not produce toxin.
3. It should not produce antibiotics that can destroy the enzyme
33
They are the agents that accelerate the rate of reactions without themselves undergoing any net chemical modification.
Catalysts
34
They function similarly by reducing the energy barrier required for the
transformation of a reactant into a product.
Catalysts
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Mechanism of Enzyme Action
These are the molecule that binds to the active site of the enzyme.
Substrates
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Mechanism of Enzyme Action
This is the specific region or location of the enzyme which combines with the substrate.
Active site
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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
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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
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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
40
Mechanism of Enzyme Action
Unlike the lock-and-key model, the __________ shows that enzymes are rather flexible structures.
Induced-fit model
41
Is the protein part of the enzyme and in most cases inactive or possess no catalytic activity.
Apoenzyme
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It contains contains a protein part plus a prosthetic group and the active form of the enzyme.
Holoenzyme
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Are compounds that are indispensable to enzyme action.
Prosthetic group
44
What are the Prosthetic group?
1. Coenzyme
2. Cofactor
3. Ligands
45
Prosthetic group:
The vitamin derived and in most cases water soluble vitamins.
Coenzyme
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Prosthetic group:
Metals and Minerals
Cofactor
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Prosthetic group:
Biomolecules such CHO or lipids attached to the protein part of the enzyme.
Ligands
48
Is a group of enzymes that catalyzes a single reaction only. They are multiple in forms and differs in amino acid sequence.
Isozymes
49
Is the part of the enzyme where the chemical reaction occurs. This is also the binding site of the substrate.
Active site
50
These are substances that can either activate or inhibit the enzyme by altering the conformation of the active site.
Allosteric factor
51
Is the study of the rate of enzyme-catalyzed reactions.
Enzyme Kinetics
52
The transitory of molecular structure in which the molecule is no longer a substrate but not yet a product.
Transition state
53
Is the amount of energy needed to bring 1 mole of the reactants to the transition state.
Activation energy
54
What are the 6 groups of enzyme classification and nomenclature?
1. Oxidoreductases (EC 1)
2. Transferases (EC 2)
3. Hydrolases (EC 3)
4. Lyases (EC 4)
5. Isomerases (EC 5)
6. Ligases (EC 6)
55
It catalyze oxidation reduction reactions.
Oxidoreductases
56
Examples of Oxidoreductases
- Polyphenoloxidase
- Catalase
- Peroxidase
- Lipoxygenase
- Glucose oxidase
57
It catalyze reactions involving transfer of functional groups.
Transferases
58
Examples of Transferases
- Cyclodestrin glycosyltransferase
59
It catalyze hydrolytic reactions.
Hydrolases
60
Three kinds of Hydrolases are:
1. Peptide-hydrolases: proteolytic enzymes (e.g. papain).
2. Glycoside-hydrolases: amylolytic enzymes, cellulases, hemicellulases, invertase.
3. Ester-hydrolases: pectin-esterase, lipase, chlorophylase, ribonucleas.
61
It catalyze reactions involving addition of double bonds.
Lyases
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Examples of Lyases
- Endo-pectate lyase,
- Endo-pectin lyase
63
It catalyze isomerization reactions.
Isomerases
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Example of Isomerases
- Glucose isomerase
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It catalyze formation of bonds involving the use of ATP.
Ligases
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Most restrictive type of specificity. The enzyme will catalyze only one reaction with a specific substrate.
Absolute specificity
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Example of Absolute specificity
urease acts only urea; maltase acts only to maltose
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The enzyme will act only on molecules that have specific functional groups.
Group specificity
69
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.
70
The enzyme will act on a particular type
of chemical bond regardless of the rest of the molecular structure.
Linkage specificity
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Example of Linkage specificity
lipase – acts on an ester bond
72
The enzyme will act on a
particular steric or optical isomer.
Stereochemical specificity
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Example of Stereochemical specificity
amylase – specific for alpha-linkages
74
What are the 5 enzyme activity and inhibition?
1. Temperature
2. pH
3. Substrate concentration
4. Enzyme concentration
5. Enzyme inhibitors
75
Temperature
Generally most enzymes have optimum temperature at 30 to 40 °C. At higher temperature, activity decreases due to protein denaturation.
76
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.
77
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.
78
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.
79
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.
80
The enzyme production and use of enzymes is a major part of ____________ industry.
Biotechnology
81
The first enzyme produced in 1896 which is a fungal amylase used to cure digestive disorders.
Taka- Diastase
82
Sources of enzymes in plants.
1. Bromelain
2. Esterase
3. Ficin
83
Sources of Enzymes in animals.
1. Lipase
2. Pepsin
3. Rennin
84
Challenges of using plants and animals as source of enzymes.
1. High cost
2. Difficult to isolate and purify
3. High risk
85
The most significant and convenient source of commercial enzymes used in the industry.
Microorganisms
86
This source of enzyme in microorganisms can produce at least 40 commercial enzymes.
Aspergillus Niger
87
What are the 4 steps in microbial production of enzyme?
1. Selection of organism
2. Formulation of Medium
3. Production Process - Fermentation
4. Recovery and Purification
88
In the first step of microbial production of enzyme, selection or organism should be:
* Non-pathogenic cell
* Less fermentation time
* Simple isolation and separation
89
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
90
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
91
What are the 2 fermentation in the third step of microbial production of enzyme which is the production process?
1. Submerged culture fermentation (SCF)
2. Solid state fermentation (SSF)
92
It is commonly used for industrial application for microbes that require high MC.
Submerged culture fermentation (SCF)
93
It gives more yield and less chances of infection, and also employs liquid substrate such as broth and molasses.
Production process – Fermentation
94
It is used for microbes that require less moisture content for growth. Specifically, for isolation of enzymes from fungi.
Solid state fermentation (SSF)
95
The substrates used for this one include bran, bagasse, and paper pulp.
Solid state fermentation (SSF)
96
It is less effluent and waste materials can be recycled.
Solid state fermentation (SSF)
97
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
98
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.
99
Defined as the imprisonment of cell or enzyme in a distinct support or matrix.
Enzyme Immobilization
100
The first immobilized enzyme was ________________ of Aspergillus oryzae for the production L-amino acids in Japan.
Amino acylase
101
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.
102
Why immobilize enzymes?
1. Accelerate the reaction
2. Specificity and unmodified
3. Cost-effective
4. Easy to separate
5. Can be re-used
103
ADVANTAGES OF IMMOBILIZED ENZYMES
1. Increased functional efficiency
2. Enhanced reproducibility
3. Reuse of enzymes
4. Continuous use
5. Less labor input
6. Saes capital const and Investment of the process
7. Minimum reaction time
8. Less contamination in products
9. More stability of products
10. Stable supply of products
11. Improved process control
12. High E:S (enzyme:substrate) ratio
104
DISADVANTAGES OF IMMOBILIZED ENZYMES
1. High cost for the isolation, purification and recovery of active enzyme.
2. Applications are limited – very few industries use immobilized enzymes.
3. Catalytic process are reduced and completely lost after immobilization.
4. Some enzymes become unstable after immobilization.
5. Enzymes are inactivated by the heat generated in the system.
105
APPLICATION OF IMMOBILIZED ENZYMES
1. Industrial Production
2. Biomedical Applications
3. Food Industry
4. Research
5. Production of biodiesel
6. Waste water management
7. Textile
8. Detergent
106
It holds the enzyme permanently or temporarily for a period of time. It also should be cheap and easily available.
Support or Matrix
107
Characteristics of ideal matrix should be:
* Economical
* Chemically inert
* Stable
* Natural / Synthetic
* Organic/ Inorganic
* Enhance enzyme stability
* Regenerable
108
Support of Matrix: Organic
* Cellulose
* Dextrans
* Agar
* Agarose
* Chitin and chitosan
* Alginate
* Collagen
* Polyacrylate
* Polystyrene
109
Support of Matrix: Inorganic
* Zeolites
* Ceramics
* Silica
* Glass
* Activated carbon
* Metals
* Charcoal
110
METHODS OF ENZYME IMMOBILIZATION
1. Binding > Adsorption > Covalent
2. Physical Retention > Entrapment > Encapsulation
111
In this method of enzyme immobilization, there is a direct physical and/or chemical interaction between the carrier and enzyme.
Immobilization by binding
112
In Immobilization by binding, the binding of enzymes to carriers is achieved via _____________ or _________________.
adsorption
covalent mechanisms
113
The binding on the surface of the
carrier. It is also the oldest and simplest method of enzyme immobilization.
Adsorption
114
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
115
Adsorption matrices involves:
silica, charcoal, and clay
116
It affects the binding in adsorption.
Change in pH, temperature and ionic strength.
117
The binding is through sharing of electrons between the carrier and the enzyme.
Covalent
118
It is a permanent method for enzyme immobilization and provides stronger bonds than adsorption.
Covalent
119
The active enzyme is covalently bonded with a linking agent.
Crosslinking
120
Functional groups that forms covalent bonds:
* Amino group
* Hydroxyl group
* Carboxyl group
* Phenol rings
* Thiol and methyl thiol groups
121
Immobilization of enzymes is done through matrix entrapment or membrane closures.
Immobilization by physical retention
122
In this enzyme immobilization, enzyme is
entrapped in a gel matrix.
Matrix entrapment
123
Matrix entrapment
Substrate is passed through a column filled with _______ and the end result is the product.
Beads
124
Matrix entrapment
Enzymes are supported on ________ format made up of collagen, cellulose etc.
Fiber
125
It is a fast method of enzyme immobilization.
Matrix entrapment
126
In this enzyme immobilization, enzymes can move in a well-defined space but is limited.
Membrane enclosures
127
It is the formation of a polymer around
the enzyme.
Encapsulation
128
It is cheap and simple method of enzyme immobilization and has membrane reactors.
Membrane enclosures
129
Significance of Enzymes in the Food Industry:
*Produce high quality products
*Low production cost
*Minimal waste
*Minimum energy consumption
*Biodegradability
130
Enzyme are used in the baking industry for:
*Dough handling
*Taste
*Color
*Moisture and volume
*Control of overcrumb texture
131
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
132
In the baking industry, β-AMYLASE:
* Improves yeast fermentation
* Increases bread volume
133
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
134
In the baking industry, LIPOXYGENASE:
Used for bread whitening
135
In the baking industry, HEMICELLULASE:
* Improves dough property
* Decrease stickiness of bread
136
In the baking industry, PENTONASES:
* Improves dough machinability – more stable, flexible and easy to handle dough.
* Better storage properties
* Softer crumb
* Improves volume
137
In the baking industry, PROTEASE AND PROTEINASE:
* Reduces gluten elasticity in biscuits and wafer production
* Improves elasticity
* Improves volume
138
In the baking industry, GLUCOSE OXIDASE:
* Oxidizes glucose and produce gluconic acid and hydrogen peroxide.
* Strengthens cross-links in gluten
139
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”
140
In the dairy industry, LACTASE:
* Artificially extracted from yeast.
* Used in the production of lactose free milk, ice cream, sweetened flavored and condensed milk.
141
In the dairy industry, CATALASE:
* Produced from bovine livers and microbial source.
* Prevent oxidation – breaks down hydrogen peroxide.
142
In the dairy industry, PROTEASE:
* Hydrolyzes specific peptide bond to generate casein in the production of cheese.
* Used to develop flavor compounds.
143
In the dairy industry, LIPASES:
* Flavor development – increase sweetness
* Prevent crystallization
* Fat hydrolysis
144
In the dairy industry, PROTEASE:
* Useful during the malting process
* Breaks larger protein which enhances the retention of beer
* Reduces haze
145
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
146
In the brewing industry, α- AMYLASE:
* Converts starch dextrin
* Solubilized carbohydrates found in barley and other cereals
* Decreases the time required for mashing
147
In the brewing industry, AMYLOGLUCOSIDASE:
* Caramelization of saccharides
* Not thermostable
* Results in product loss and increase in impurities
148
In the meat industry, PROTEASE:
* Bromelain (pineapple), papain (papaya)
* Immobilized from Bacillus spp with alginate gel as the matix
(entrapment method)
149
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
150
In the meat industry, TRANSGLUTAMINASE:
* Induce gelation in meat products
151
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)
152
In the sugar industry, AMYLOSE AND AMYLOPECTIN:
* Mixture
* Converts starch into glucose
153
In the sugar industry, β-AMYLASE AND POLLULANASE:
* Used to produce maltose syrup
154
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
155
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
156
In the beverage industry, β-GLUCANASE:
* Improves clarification and filtration
* Reduces maturation duration
157
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.
158
Responsible for the browning reactions of cut fruits.
Phenolase
159
Important in juice clarification.
Pectinase
160
Used as meat tenderizer, partially hydrolyzes collagen and elastin.
Proteinase
161
An endoenzyme, cleaves glycosidic bonds inside the starch molecule, decreasing its viscosity.
Alpha-amylase
162
Is a saccharifying enzyme, increasing sweetness by cleaving glycosidic bonds outside the starch molecule.
Beta-amylase
163
Used for bleaching flour; may destroy carotenol and vitamins; and results to off odor and off flavor in soy products.
Lipoxygenase
164
Catalyze oxidation of glucose preventing maillard browning.
Glucose oxidase
165
Converts sucrose to fructose and glucose; prevents crystallization of sugar in jams.
Invertase
166
Converts glucose to fructose, important in producing high fructose syrup.
Glucose isomerase
