list of enzymes

8/2/2019 List of Enzymes

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Enzymes


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Proteases Protease is the digestive enzyme needed to

digest protein.

The enzyme Proteases also called proteolyticenzyme & PeptideCutter.

Protease refers to a group of enzymes whose

peptide bonds of proteins. They are also calledproteolytic enzymes or proteinases.

Proteases differ in their ability to hydrolyzevarious peptide bonds. Each type of proteasehas a specific kind of peptide bonds it breaks.

Examples: Pepsin, Trypsin, Chymotrypsin,a ain.


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Mechanistic Sets of Proteases

set feature inhibitor examples function

Serine protease active site serine fluorophosphates trypsin digestion

thrombin blood coagulationplasmin lysis of blood clotscoccoonase mechanicalsubtilisin digestionacrosin sperm penetration

Cysteine protease active site cysteine iodoacetate papain digestionstrept. proteinase digestioncathepsin B intracell. digestion

Acid protease acidic pH optimum diazoketones pepsin digestion

chymosin milk coagulation

Metalloproteases Zn2+, o-phenanthroline carboxypeptidase digestionZn2+, Ca2+ o-phenanthroline thermolysin digestion


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Proteases

What do proteases do?

Proteases cleave proteins by a hydrolysis reaction the addition of

a molecule of water to a peptide bond

Proteases belong to the class of enzymes known as hydrolases,which catalyse the reaction of hydrolysis of various bonds(peptidebond, ester bond etc.) with the participation of a water molecule.

Proteases are involved in digesting long protein chains into shortfragments, splitting the peptide bonds that link aminoacid residues.


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Occurrence Proteases occur naturally in all organisms. Theseenzymes are involved in a multitude of physiological

reactions from simple digestion of food proteins tohighly regulated cascades (e.g., the blood-clotting

mechanism). Proteases can either break specific peptide bonds

(limited proteolysis), depending on the amino,

peptide to amino acids (unlimited proteolysis). Bacteria also secrete proteases to hydrolyse (digest)

the peptide bonds in proteins and therefore break theproteins down into their constituent monomers.Bacterial and fungal proteases are particularlyimportant to the global carbon and nitrogen cycles inthe recycling of proteins, and such activity tends to beregulated in by nutritional signals in these organisms.


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How Protease Deficiency Can

Affect Your Health Acidity is created through the digestion of protein. Therefore a

protease deficiency results in an alkaline excess in the blood. Thisalkaline environment can cause anxiety and insomnia.

In addition, since protein is required to carry protein-bound calcium inthe blood, a protease deficiency lays the foundation for arthritis,osteoporosis and other calcium-deficient diseases.

Because protein is converted to glucose upon demand, inadequateprotein digestion leads to hypoglycemia, resulting in moodiness,mood swings and irritability.

Protease also has an ability to digest unwanted debris in the blood

including certain bacteria and viruses. Therefore, protease deficientpeople are immune compromised, making them susceptible tobacterial, viral and yeast infections and a general decrease inimmunity


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Functions of proteases

Proteases are used throughout an organism for variousmetabolic processes.

Acid proteases secreted into the stomach (such as pepsin) andserine proteases present induodenum (trypsin and chymotrypsin) enable us to digest theprotein in food.

Proteases present in blood serum play important role in blood-

the immune system. Proteases determine the lifetime of other proteins playing

important physiological role like hormones, antibodies, or otherenzymesthis is one of the fastest "switching on" and

"switching off" regulatory mechanisms in the physiology of anorganism. Proteases are part of many laundry detergents.


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Classification Exopeptidases Some of them can detach the terminal amino

acids from the protein chain is calledexopeptidases. eg. Amino peptidases, carboxypeptidase.

Endopeptidases Some of them can attack internal peptide bonds

of a protein chain is called endopeptidases. eg. Trypsin, chymotripsin, pepsin, papain.


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Classification Proteases are divided into four major groups

according to the character of theircatalytic active site.

Serine proteinases Eg: Trypsin,Chymotripsin. eg: Bromelain (pineapple), Papain(papaya). Aspartic proteinases

eg: Pepsin Metalloproteinases eg: Collagenase.


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Serine proteases

Serine proteases (serine endopeptidases)are enzymes that cleave peptide bonds in proteins, in

which serine serves as the nucleophilic amino acid atthe active site.

They are found in both eukaryotes and prokaryotes.

eg: ymo ryps n an ryps n. In humans, they are responsible for co-ordinating

various physiological functions, including digestion,immune response, blood coagulation andreproduction.


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Cysteine proteases Biological importance Cysteine proteases play an important role in every

aspect of physiology and development in plants. In humans they are responsible for immune

responses, prohormone processing, and extracellularmatrix remodeling important to bone development.

n severa tra t onamedicines the fruits of papaya, pineapple and fig arewidely used for treatment of intestinalworm infections in humans. Cysteine proteinases

isolated from these plants have been found to havehigh proteolytic activities that are knownto digest cuticles, with very low toxicity.


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Aspartic proteases

Aspartic proteases area family of protease enzymes that usean aspartate residue for catalysis of their peptide

substrates.

Aspartyl proteases play an important role in several

blood pressure (renin), digestion (pepsin andchymosin).

Aspartate proteases include

the digestive enzyme pepsin

Some proteases found in lysosomes

the kidney enzyme renin

HIV-protease.


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Metalloproteinases Metalloproteinases (metalloproteases) constitute a family

of enzymes from the group of proteases, classified by thenature of the most prominent functional group in their activesite.

These are proteolytic enzymes whose catalytic mechanisminvolves a metal.

Most metalloproteases are zinc-dependent, but some.

The digestive enzyme carboxypeptidase is a classic exampleof the zinc proteases.

Zinc proteases (metalloproteases) include: digestive enzymes carboxypeptidases

matrix metalloproteases (MMPs), secreted by cells

one lysosomal protease.


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Protease Applications in Food Processing

Basic rationale: Proteases are a powerful tool formodifying the properties of food proteins.

Improved digestibility Improved solubility

Modified functional properties: emulsification, fat-, - , ,

strength, whipping properties, etc.

Improved flavor & palatability

Improved processing: viscosity reduction, improveddrying, etc.


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Protease Applications in Food Processing

Proteases are also used in a wide range of foods &food processing applications.

Dairy: milk coagulation, flavor development

Baking: gluten development Fish & seafood processing: fishmeals, enhanced oilrecovery, aquaculture

reduced allergenicity, improved flavor, meattenderization

Plant protein processing: improved functionality &processing, generation of bio-active peptides.

Yeast hydrolysis: flavor compounds.


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Nonfood Protease Applications

Medicine Pharmacology & drug

manufacture

Laundry & dishwashingdetergents (#1)

Hard surface cleaningformulations

Contact lens cleaningformulations

Waste treatment

Industrial applications

Fermentation (fuel EtOH, etc.) Chondroitin & heparin

production

Animal feed additives

Digestive supplements


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Carbonic anhydrases

The carbonic anhydrases (carbonate dehydratases)form a family of enzymes that catalyze the rapidinterconversion of carbon

dioxide and water to bicarbonate and protons. Carbonic anhydrases are enzymes that catalyze the

hydration of carbon dioxide and the dehydration of

car ona e: CO2 + H2O HCO3- + H+

One of the functions of the enzyme in animals is tointerconvert carbon dioxide and bicarbonate tomaintain acid-base balance in blood and other tissues,and to help transport carbon dioxide out of tissues.

The carbonic anhydrases making fast reaction faster.


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Structure and types of carbonic anhydrase

Several forms of carbonic anhydrase occur in nature. In the best-studied -carbonic anhydrase form present in

animals, the zinc ion is coordinated by the imidazole rings of 3histidine residues.

The primary function of the enzyme in animals is to interconvertcarbon dioxide and bicarbonate to maintain acid-base balancein blood and other tissues, and to help transport carbon dioxideout of tissues.

an s con a n a eren orm ca e - ,which is a distinct enzyme, but participates in the same reactionand also uses a zinc ion in its active site. In plants, carbonicanhydrase helps raise the concentration of CO2 withinthe chloroplast in order to increase the carboxylation rate of the

enzyme RuBisCO. This is the reaction that integratesCO2 into organic carbon sugars during photosynthesis, and canuse only the CO2 form of carbon.


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Reaction The reaction catalyzed by carbonic anhydrase is:

(in tissues - high CO2 concentration) . The reaction rate of carbonic anhydrase is one of the fastest

of all enzymes, and its rate is typically limited bythe diffusion rate of its substrates.

The reverse reaction is also relatively slow, which is why acarbonated drink does not instantly degas when opening the

comes in contact with carbonic anhydrase that is contained insaliva. An anhydrase is defined as an enzyme that catalyzes the

removal of a water molecule from a compound, and so it is this"reverse" reaction that gives carbonic anhydrase its name,because it removes a water molecule from carbonic acid. (in lungs and nephrons of the kidney - low

CO2 concentration, in plant cells)


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Functions of carbonic anhydrase

While the main carbonic anhydrase function is workingas a catalyst for the conversion of water and carbondioxide (making it essential to the breathing processand the spread of oxygen to the cells in the body), italso plays other roles. These include:

Plays a key role in the digestion process. The enzyme

ma n a ns e a a ne eve o pancrea c u ces w eretaining the salivas neutral level to make sure thatthe body is digesting food as it should.

Helps in the treatment of glaucoma. Carbonic

anhydrase inhibitors are actually used to treatglaucoma. One of the possible causes of this eyecondition is fluid build-up in the eye area, which cancause damage to the optic nerves.


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The enzyme can also be used to treat hypertension

Works as a diuretic. By reducing the amount of saltand bicarbonate absorbed by the body, the enzymealso has diuretic effects that can help the body flushout harmful toxins in the system.

Maintains pH and fluid homeostasis in the body. Theenzyme is responsible for regulating the bodys pHlevel as well as fluid balance of the body.

ar on an y rase unct on s many an var e ,depending on where the enzyme is located. Shouldthere be abnormalities involving the enzyme, such asthe body having too much or too little of it, the body

can suffer, with possible problems including poordigestion and kidney failure.


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Restriction enzymes

A restriction enzyme is an enzyme that cutsdouble-stranded or single stranded DNA atspecific recognition nucleotide sequences

known as restriction sites. Restriction enzymes are called molecular

scissors.

Nucleases are further described by addition ofprefix endoor exoto the name.

Endonucleases break nucleotides at the middle

and exonucleases break the nucleotides at theend of the molecule.


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Cut and ligate 2 DNAs with EcoRI --->

recombinant DNA


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Restriction enzymes recognize a specificsequence of nucleotides, and produce adouble-stranded cut in the DNA. These cuts areof two types:

STICKY ENDS

BLUNT ENDS.


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Restriction enzymes

Recognizes specific basesequences in double-helical DNAand cleave, at specific places, bothstrands of a duplex containing therecognized sequences.

Restriction enzymes recognizespecific bases pair sequences in

Restriction

enzyme

cleave the DNA by hydrolyzing thephosphodiester bond.

Cut occurs between the 3 carbon

of the first nucleotide and thephosphate of the next nucleotide.

Restriction fragment ends have 5

phosphates & 3 hydroxyls.


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TYPES OF RESTRICTION ENZYMES

Restriction endonucleases are categorizedinto three general groups.

Type I

Type II Type III

ese types are categor zat on ase on:Their composition.

Enzyme co-factor requirement.

the nature of their target sequence.

position of their DNA cleavage site relative to

the target sequence.


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Type I restriction enzymes were the first to be

identified and are characteristic of two different strainsof E. coli. The recognition site is asymmetrical and iscomposed of two portions one containing 3-4nucleotides, and another containing 4-5 nucleotides

separated by a spacer of about 6-8 nucleotides.

Type II restriction enzymes - They are composed of.

undivided and 4-8 nucleotides in length, theyrecognize and cleave DNA at the same site.

Type II restriction enzymes - Type III restriction

enzymes recognize two separate non-palindromicsequences that are inversely oriented. They cut DNAabout 20-30 base pairs after the recognition site.These enzymes contain more than one subunit.


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APPLICATION OF RESTRICTION ENZYMES

They are used in gene cloning and protein

expression experiments.

Restriction enzymes are used in biotechnology to

cut DNA into smaller strands in order to studyfragment length differences among individuals(Restriction Fragment Length Polymorphism

RFLP).


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Nucleoside Phosphate Kinase It is an enzyme that catalyzes the phosphoryl group exchange

between nucleotides without promoting hydrolysis.

It is also known as phosphotransferase. It is a type enzyme that

transfers phosphate group from high energy donor moleculesuch as ATP to specific target molecule i.e., substrate. Thisprocess is termed as phosphorylation.

2+.

Thus, the two substrates of this enzyme are ATP andnucleoside phosphate, whereas its two products are ADP andnucleoside diphosphate.

list of enzymes

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