Unit 3 Flashcards
How do enzymes accelerate rate of chemical change
- by lowering the activation energy
What is activation energy
- it’s the minimum energy needed to convert reactant to product
Cells undergo a biochemical activity called
metabolism
What is metabolism
- its the process of chemical and physical changes, including the breakdown (catabolism) and synthesis (anabolism) of molecules.
Do enzymes change or remain unchanged after they act on substrates
they remain unchanged
Do enzymes affect the nature of the product
No they don’t
List the physical properties of enzymes
- Denaturation
- solubility
- colloidal
- enzyme precipitation
- molecular weight
- enzymatic activity
- biocatalyst property
List the chemical properties of enzymes
- heat and ph sensitivity
- regulation
- catalysis
- reversiblity
- specificity
What is denaturation
is the process of breaking the intra and inter-molecular non-covalent bonds that distort the shape and active site of the enzymes.
Enzymes are denatured by
- high heat ( above 40 c)
- change in ph
- heavy metal
- high salt concentration
- solvent
Enzymes are soluble in
- water
- salt (NaCl)
- diluted glycerol
-alcohol
They cause denaturation.
What is the colloidal nature of enzymes
nature of enzyme is the tendency of having little or no dialysis cross the semipermeable membrane due to the large size or high molecular weight
What is the biocatalyst property
is the activity of enzymes in which very small quantities or a small amount of enzyme is enough to convert a large quantity of substrate and remain unchanged after the reaction
What is enzyme precipitation
is the separation of enzymes for analysis using different aqueous or ethanol solvents
What is molecular weight of enzymes
Enzymes are large protein bio molecules that hold polypeptide chains of various amino acid sequences
Because of this they have high molecular weight
What is enzymatic activity
Is the general catalytic properties of an enzyme
The enzymatic activity depends on factors such as
- temperature
- ph
- concentration of substrates and enzymes
What is regulation
is the process of controlling the activity of enzymes by activator and inhibitor molecules
What is catalysis
- is the process of the acceleration of a chemical reaction by a catalyst
- Enzymes are biological catalysts that possess high catalytic efficiency
- They can transform about 100-10,000 substrates per second
- The reactions catalyzed by the enzymes show a 10^3-10^8 times faster reaction rate in comparison to the non-catalyzed reactions
What is reversiblity
- is the ability of enzymatic biomolecules to catalyze forward and reverse reaction
What is bond specificity
is a relative specificity of enzymes, which indicates that enzymes
are specific for a bond
What is group specificity
Is a structural specificity of enzymes which describes that enzymes are specific for a group
What is substrate specificity
is the feature of enzymatic activity where an enzyme acts
only on a particular substrate
What is optical specificity
is when enzymes act on the substrate optical configuration
What is co factor specificity
is the enzymatic specificity to the substrate and co-factors
What is the turn over number of molecules
is the number of substrates converted by one enzyme molecule per second at saturated ( fully occupied)active sites
Enzymes are markers of the states of various diseases like
- myocardial infraction
- jaundice
- pancreatitis
- cancer
- neurodegenerative disorders
Sucrase
Brakes down sugar called sucrose
Lactase
Breaks down sugar called lactose into glucose and galactose
Is found in the small intestine
Carbohydrase
Breaks down carbohydrates into sugar
Lipase
Breaks down fats into fatty acids
Found in the blood, gastric juices, pancreatic secretions, intestinal juices
Adipose( fatty) tissues and participate in digestion
Protease and trypsin
Breaks down protein into amino acids
Amylase
Breaks down starch into sugar
Is found in the saliva
Maltase
Breaks down sugar maltose into glucose
- found in foods such as potatoes, pasta , beer and saliva
Helicase
Unwinds dna
DNA polymerase
Is responsible for forming new copies of dna in the form of nucleic acids molecules
Acetyl cholinesterase
Breaks down the neurotransmitter acetylcholine in nerves and muscles
What is protein structure
It’s a polymer of amino acids joined by peptide bonds with three dimensional arrangements of atoms in amino acid chain molecules
When is a polypeptide called a protein
One it’s folded and it becomes functional
Some proteins are made of more than one folded polypeptide chain
What are the four structural levels of proteins
1 primary structures
2 secondary structures
3 tertiary structures
4 quaternary structures
What is primary structures
It’s the linear sequence of amino acids
How many sequences of amino acids do we need to form polypeptide
- if it’s less than 50 sequences it’s peptides
- if it’s greater that 50 sequences it’s polypeptide
How many amino acids do our body require and where do we get these
- require 20 amino acids
- 10 are synthesized in the body
- 10 are obtained from diets
Cells use 20 different standards of L-a- amino acids containing
Basic amino acids and acidic carboxyl groups
What is secondary structures
It’s a folded structure formed within a polypeptide due to interactions between atoms of the backbone based on hydrogen bonding
The two types of strands in secoundary structures are
- the alpha helix
- beta pleated sheet
Is the alpha helix a right handed coiled strand or a left handed coiled strand
Right handed coiled strand
The side chain substituents of amino acids is extend to
The outside
The hydrogen bond occurs between the
Oxygen ( c=o ) with the hydrogen ( N-H) in groups of four amino acids
The hydrogen bonding in beta pleated sheets is between
The inter- strand and intra - strand in which the sheet conformation of the beta pleated sheet consists of pairs of strands lying side-by- side
What is the tertiary structure of proteins
is the three-dimensional shape of protein molecules that bend and twist to achieve the maximum stability or the lowest energy state
- it’s fashioned by many stabilizing forces
What is the quaternary structure of proteins
All polypeptide chains are held together by a specific spatial arrangement and interactions
What are the two enzyme substrate binding models
- enzyme lock and key model
- enzyme induced for model
List some characteristics of lock and key model
- there is no change in the active site before and after a chemical reaction
- non covalent interaction
- the enzymes must bind to substrates before they catalyze a chemical reaction
List some properties of enzymes induced fit model
- enzyme changes shape upon substrate binding which either suppresses or enhances the activity of the enzyme
- the amino acid side chains that make up the active site mold into a precise position
- they lower the activation energy by putting the active site under strain which makes the transition stable
How does the transition state determine the reaction rates of elementary chemical reaction
Because the enzymatic rate is directly influenced by the stability of the transition state
In the transition state there is chemical equilibrium between _____________ and __________________
- reactant
- activated transitions
The transition state describes how the chemical reaction is taking place ____________ in the activated enzyme substrate complex
-qualitatively
What is enzyme regulation
It is adapting enzymatic activities by other molecules or metabolic cells to either increase or
decrease the activities.
Regulatory enzymes require______________to become active and pass through some modifications and function
- An extra activation process
What are allosteric enzymes
Are enzymes that have an additional binding sites for effector molecules that cause conformational change
List some characteristics of effectors in allosteric enzymes
- can be inhibitor or activator
- lead to structural changes in the concrete part, which affects the structure of the active site , which causes change In the activity of the reaction
- adjust the enzyme activity through reversible non covalent binding
What do genetic and covalent modification modify?
-modify the protein surface and facilitate intracellular delivery
What are covalent modifications
are enzyme-catalyzed alterations of synthesized proteins by the
addition or removal of chemical groups
__________ is the most common regulatory modifications
Phosphorylation (addition of phosphate group to protein)
What is enzyme inhibition
Is a decrease in enzyme activity by enzyme inhibitors
Enzyme inhibition is classified into
- reversible inhibition
- irreversible inhibition
What is irreversible inhibition
A substance that permanently blocks the action of an enzyme
What is reversible inhibitor? It can be classified into?
- it inactivates an enzyme through non covalent easily reversed interactions
- it’s classified into competitive,uncompetitive and non competitive inhibition
What is competitive inhibitor
It is a molecule that blocks the binding of the substrate to the active site
It depends on the concentration
What is a non competitive inhibitor
It binds to the allosteric site
Decreases the efficiency of the enzymes
What is uncompetitive inhibitor
Doesn’t bind to the free enzyme
Occurs in reactions with two or more substrates or products
Enzymes types are based on
- enzymes that bind specific molecules together
to form new molecules - enzymes that break specific molecules apart into separate molecules.
Enzymes are structural classified into
- simple protein( active )
- conjugated protein ( holoenzyme )
Conjugated protein (holo enzyme) is classified into
- Protien part (Apoenzyme )
- non protein part(co factor)
Non protein part( cofactor) is classified into
- firmly attached ( usually metal ion ) (prothetic group)
- loosely attached( usually vitamin B complex) (coenzyme)
Enzymes are composed of six classes based on
- what and how they react
- the type of reaction they catalyze
- the end suffix “ase”
Oxidoreductase
catalyzes oxido-reduction reactions
Transferase
transfers methyl groups from one compound donor as a cofactor to another compound (acceptor), carry and transfers
Hydrolases
catalyze the hydrolysis of various bonds
Lyases
are enzymes that cleave bonds by other means rather than hydrolysis or
oxidation in which two or more substrates are involved in one reaction
Isomerases
convert molecules from one isomer to another isomer
Ligases
are enzymes that catalyze the joining of two molecules with concomitant hydrolysis of the di-phosphate bond in ATP or a similar triphosphate
Factors that affect enzyme activity are
- temperature
- ph
- inhibitor
- water
- radiation
- activator
- substrate
- enzyme
- end product concentration
Ph is ________ written in short
Potential of hydrogen ions
How does radiation affect enzyme activity
- reduces enzymatic efficiency
- creates disorders in the macromolecules
Give an example of a feedback inhibition
- the drug Tipranivir used to treat HIV blocks the activity of a viral genome enzyme ( this enzyme produces more copies of the virus )
- the drug is a reversible inhibitor
Enzyme kinetics describes
- the rate of chemical reactions catalyzed by enzymes
- the binding affinities of substrates
- the maximal catalytic rate
- inhibitor
______________ and __________ determine production volumes per unit time( rate of reaction)
- the concentration of enzymes
- the concentration of substrates
The most common model of enzyme kinetics is
Michaels- Menten formula
The Micheal - menten formula describes the rate of enzymatic reaction by relating ___________ and _____________ with _______________
- the reaction rate
- rate of formation of product
With - concentration of substrate
Enzyme catalyst is ____to _____ times higher than inorganic catalyst
100s to 1000s
Enzymes used for food industry were extracted from
from the internal organs of animals and plants, but now most enzymes are obtained by microbial fermentation
Cellulases
- Biofuel industry
- Breakdown cellulose into sugars and ferment to produce cellulosic ethanol
Ligninase
-Biofuel industry
-Pre-treatment of biomass for biofuel production
Protease,Amylase, Lipase
- biological detergent
- Remove protein, starch, and fat or oil stains from laundry and dishware.
Mannanase
Biological detergent
Betaglucanase
- Brewing industry
- Improve beer filtration
Papain
- Culinary uses
- Tenderize meat for cooking
Rennin
-Dairy industry
- It hydrolyses protein in the manufacture of cheese
Trypsin
-Food processing
- Manufacture hypo-allergenic baby foods
Cellulases, Pectinase
- Food processing
- Clarify fruit juices.
Nuclease, DNA Ligase, Polymerase
- Molecular biology
- Uses restriction digestion and polymerase chain reaction to create recombinant DNA
Steeping is the process of
-cleaning the grain kernels
- activating enzymes and simulating the production of enzymes by immersing it in water and air for a specific time period
- occurs over a period of 24-48 hours
Germinating
- is continuing the process with the growth and modification of the grain
- growth : rootlets emerge from the kernel to the outside of the grain and within the outer husk a shoot or acrospires grows
Kilning is a heating treatment which
- drys the green malt
- gets the moisture so it stops germinating
- prepares the malt for flavour and colour development
The killing process achieves
- enzymatic activity
- friablity
- a wide range of malt colours and flavours
- distinctive ales and lagers
What would happen if the killing process didn’t stop the germination
- the kernel would keep growing and the growing plant would use all of the starch reserves needed by the brewer
In the killing process we first remove the moisture for _________ and we further remove for _________
- withering
- we further remove the moisture to prepare the malt for flavour and Color development
