pectin and pectic enzymes

Views:
 
     
 

Presentation Description

enzymology

Comments

By: Mahadi64 (1 month(s) ago)

Very useful presentation ... Please forward me too Thanks

By: raj.chandramani (19 month(s) ago)

nice presentation.......... please forward me

By: Mahadi64 (1 month(s) ago)

Very useful presentation.......... please forward me too Thanks

 

Presentation Transcript

Pectin and pectic enzymes : 

Pectin and pectic enzymes

PECTIN : 

PECTIN Occurs in plant middle lamella Gel former, e.g., fruit jelly From the Greek word meaning to congeal  Pectin was discovered in 1790 by  Vauquelin and later (1825) crudely characterized by Braconnot

Pectic Substance Nomenclature : 

Pectic Substance Nomenclature Protopectin-high methyl ester content Pectinic acid-intermediate methyl ester content, soluble Salts are pectinates Pectin-intermediate methyl ester content, colloidal Pectic Acid-little methyl ester content

Slide 4: 

Other monosaccharides (L-rhamnose, L-arabinose, D-xylose) in the structure may limit the size of junctions zones that can be formed and, thus, at least partially determine ultimate gel strength

CHEMICAL STRUCTURE OF PECTIN : 

CHEMICAL STRUCTURE OF PECTIN

Commercial (Normal) Pectin : 

Commercial (Normal) Pectin Liquid or powdered Source -- mostly lemon and lime peel (20-30% pectin). This is the highest quality. Some from apple pomace (10-15% pectin) Pectin grade = number of pounds of sugar that one pound of pectin can carry in a jelly

Pectic Substances and Gelation : 

Pectic Substances and Gelation Normal Pectin --Gels in the presence of acid and sugar Low Methoxyl Pectin --Doesn’t need sugar, but does need calcium ion Pectic Acid --Forms insoluble calcium pectate. This reaction is responsible for the firming effect seen in certain plant tissues, e.g., canned tomatoes

Pectate lyase : 

Pectate lyase In enzymology, a pectate lyase (EC 4.2.2.2) is an enzyme that catalyzes the chemical reaction Eliminative cleavage of (1->4)-alpha-D-galacturonan to give oligosaccharides with 4-deoxy-alpha-D-galact-4-enuronosyl groups at their non-reducing ends This enzyme belongs to the family of lyases, specifically those carbon-oxygen lyases acting on polysaccharides. The systematic name of this enzyme class is (1->4)-alpha-D-galacturonan lyase

Slide 9: 

Other names in common use include polygalacturonic transeliminase, pectic acid transeliminase, polygalacturonate lyase, endopectin methyltranseliminase, pectate transeliminase, endogalacturonate transeliminase, pectic acid lyase, pectic lyase, alpha-1,4-D-endopolygalacturonic acid lyase, PGA lyase, PPase-N, endo-alpha-1,4-polygalacturonic acid lyase, polygalacturonic acid lyase, pectin trans-eliminase, and Polygalacturonic acid trans-eliminase. This enzyme participates in pentose and glucuronate interconversions

Bacillus subtilis pectate lyase : 

Bacillus subtilis pectate lyase Structure Weight: 44378.38

Slide 11: 

Pectinesterase (PE) (EC 3.1.1.11) is a ubiquitous cell-wall-associated enzyme that presents several isoforms that facilitate plant cell wall modification and subsequent breakdown. It is found in all higher plants as well as in some bacteria and fungi. Pectinesterase functions primarily by altering the localised pH of the cell wall resulting in alterations in cell wall integrity

Slide 12: 

pectinesterase plays a role in the modulation of cell wall mechanical stability during fruit ripening, cell wall extension during pollen germination and pollen tube growth, abscission, stem elongation, tuber yield and root development. Pectinesterase has also been shown to play a role in a plants response to pathogen attack. A cell wall-associated pectinesterase of Nicotiana tabacum is involved in host cell receptor recognition for the tobacco mosaic virus movement protein and it has been shown that this interaction is required for cell-to-cell translocation of the virus.

Pectinesterase molecular biology and biochemistry : 

Pectinesterase molecular biology and biochemistry PE proteins are synthesised as pre-proteins of 540-580 amino acids possessing a signal sequence and a large amino-terminal extension of around 22 kDa. This terminal extension is eventually removed to yield a mature protein of 34-37 kDa

Structure of pectinesterase : 

Structure of pectinesterase The N-terminal pro-peptides of pectinesterase are variable in size and sequence and show a low level of amino acid identity. Alternatively the C-terminal catalytic region is highly conserved and constitutes the mature enzyme. To date the only known three-dimensional structure for a plant pectinesterase is for an isoform from carrot (Daucus carota) root and consists of a right-handed parallel β-helix as seen in all the carbohydrate esterase family CE-8, a transmembrane domain and a pectin binding cleft. Similarly several pectinesterase structures have been elucidated in fungi and share most of the structural motifs seen in plants

Potato pectinesterase : 

molecular weight of 25,000 pH optimum of 7.5 NaCl is a positive modulator of the enzyme Optimum temperature for the enzyme is 55°C. Potato pectinesterase

APPLICATIONS OF PECTIN : 

APPLICATIONS OF PECTIN

Slide 19: 

used to reduce blood cholesterol levels and gastrointestinal disorders edible films, paper substitute, foams and plasticizers, etc used in jams, jellies, frozen foods, and more recently in low-calorie foods as a fat and/or sugar replacer

Applications of pectinases in the commercial sector : 

Applications of pectinases in the commercial sector

Slide 21: 

fruit and textile industries bringing down the cloudiness and bitterness of fruit juices alkaline pectinases in the textile industry for the of retting of fiber crops

Slide 22: 

production of good quality paper fermentation of coffee and tea oil extractions and treatment of pectic waste water As a animal feed supplement

LIGNIN : 

LIGNIN

Slide 24: 

Complex chemical compound Derived from woods and integral part of secondary cell walls of plants and some algae Most abundant organic polymer on earth Introduced by de candolle in 1918

Slide 26: 

Fills the spaces in the cell wall between cellulose, hemicellulose, and pectin components, especially in tracheids, sclereids and xylem plays a crucial part in conducting water in plant stems it plays this role in the red alga Calliarthron, where it supports joints between calcified segments

Manganese peroxidase : 

Manganese peroxidase EC 1.11.1.13 Names Accepted name: manganese peroxidase Other names: Mn-dependent (NADH-oxidizing) peroxidase peroxidase-M2 Mn-dependent peroxidase Systematic name: Mn(II):hydrogen-peroxide oxidoreductase

Slide 29: 

In enzymology, a manganese peroxidase (EC 1.11.1.13) is an enzyme that catalyzes the chemical reaction 2 Mn(II) + 2 H+ + H2O2 2 Mn(III) + 2 H2O The 3 substrates of this enzyme are Mn(II), H+, and H2O2, whereas its two products are Mn(III) and H2O.

Slide 30: 

This enzyme belongs to the family of oxidoreductases, specifically those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is Mn(II):hydrogen-peroxide oxidoreductase. Other names in common use include peroxidase-M2, and Mn-dependent (NADH-oxidizing) peroxidase. It employs one cofactor, heme. This enzyme needs Ca2+ for activity. White rot fungi secrete this enzyme to aid lignin degradation

Lignin peroxidase : 

Lignin peroxidase Degraded by an enzyme lignin peroxidases produced by some fungi like. Phanerochaete chrysosporium In enzymology, a lignin peroxidase (EC 1.11.1.14) is an enzym that catalyzes the chemical reactio 1,2-bis(3,4-dimethoxyphenyl)propane-1,3-diol + H2O2 1-(3,4-dimethoxyphenyl)ethane-1,2-diol + H2O Thus, the two substrates of this enzyme are 1,2-bis(3,4-dimethoxyphenyl)propane-1,3-diol and H2O2, whereas its 3 products are 3,4-dimethoxybenzaldehyde, 1-(3,4-dimethoxyphenyl)ethane-1,2-diol and H2O

Lignin peroxidase H2 from Phanerochaete chrysosporium : 

Lignin peroxidase H2 from Phanerochaete chrysosporium molecular weights of two major proteins (H2 and H8)- 38,500 (H2) and 42,000 (H8) isoelectric points-4.3 for H2 and 3.65 for H8 pH optima - pH 2.5 at 25 degrees C, pH 3.0 at 35 degrees C, and pH 3.5 at 45 degrees C inhibitors - EDTA,azide,cyanide,3-amino-1,2,4-triazole

Manganese peroxidase from immobilized Phanerochaete chrysosporium : 

Manganese peroxidase from immobilized Phanerochaete chrysosporium Molecular weight - 45 000±1000 Da Optimum pH – 4.5 Optimum temperature – 30 degree C Inhibitors - 2 mM NaN3, ascorbic acid, β-mercaptoethanol and dithreitol

Laccase : 

Laccase The tricopper site found in many laccases, notice that each copper center is bound to imidazole (color code: copper is brown, nitrogen is blue). Laccases (EC 1.10.3.2) are copper-containing oxidase enzymes that are found in many plants, fungi, and microorganisms. The copper is bound in several sites; Type 1, Type 2, and/or Type 3. The ensemble of types 2 and 3 copper is called a trinuclear cluster (see figure). Laccases act on phenols and similar molecules, performing a one-electron oxidations, which remain poorly defined

Slide 39: 

It is proposed that laccases play a role in the formation of lignin by promoting the oxidative coupling of lignols, a family of naturally occurring phenols. Laccases can be polymeric, and the enzymatically active form can be a dimer or trimer. Other laccases, such as ones produces by the fungus Pleurotus ostreatus , play a role in the degradation of lignin. Substrates are ABTS, syringaldazine, 2,6-dimethoxyphenol, and dimethyl-p-phenylenediamine.

ABTS : 

ABTS

SYRINGOL : 

SYRINGOL

Laccase from Chaetomium thermophilium : 

Laccase from Chaetomium thermophilium molecular mass of 77 kDa isoelectric point of 5.1 optimum pH for enzyme activity was 6 Substrates are syringaldazine and hydroxyquinone , phenolic substrates Inhibitors are Cu-chelating agents

Slide 44: 

Coomassie blue-stained PAGE gel containing purified C. thermophilium laccase. Lane M contained standard molecular mass protein markers, including phosphorylase b (molecular mass, 104 kDa), bovine serum albumin, (82 kDa), ovalbumin (48.3 kDa), carbonic anhydrase (33.4 kDa), and soybean trypsin inhibitor (28.3 kDa). Lane 1 contained 10 μg of purified C. thermophilium laccase

Slide 45: 

The tricopper site found in many laccases, notice that each copper center is bound to imidazole (color code: copper is brown, nitrogen is blue).

Economic significance : 

Economic significance lignin extracted from shrubby willow has been successfully used to produce expanded polyurethane foam leather tanning agents Lignin removed via the kraft process (sulfate pulping) is usually burned for its fuel value, providing energy to run the mill and its associated processes

Slide 48: 

Highly lignified wood is durable excellent fuel Mechanical, or high yield pulp used to make newsprint contains most of the lignin originally present in the wood Raw materials for several chemicals, such as vanillin, DMSO, ethanol, xylitol sugar and humic acid Environmentally sustainable dust suppression agent for roads

Applications and potential utility : 

Applications and potential utility Laccases have been examined as the cathode in enzymatic biofuel cells. They can be paired with an electron mediator to facilitate electron transfer to a solid electrode wire. Laccases are some of the few oxidoreductases commercialized as industrial catalysts