Pectin lyase (), also known as pectolyase, is a naturally occurring

pectinase Pectinases are a group of enzymes that breaks down pectin, a polysaccharide found in plant cell walls, through hydrolysis, transelimination and deesterification reactions. Commonly referred to as pectic enzymes, they include pectolyase, pectozym ...

, a type of

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

that degrades

pectin Pectin ( grc, πηκτικός ': "congealed" and "curdled") is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal, chemical component o ...

. It is produced commercially for the food industry from fungi and used to destroy residual

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...

, known as

, in

wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are ...

and cider. In plant cell culture, it is used in combination with the enzyme

cellulase Cellulase (EC 3.2.1.4; systematic name 4-β-D-glucan 4-glucanohydrolase) is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysacchar ...

to generate

protoplast Protoplast (), is a biological term coined by Hanstein in 1880 to refer to the entire cell, excluding the cell wall. Protoplasts can be generated by stripping the cell wall from plant, bacterial, or fungal cells by mechanical, chemical or en ...

s by degrading the plant

cell walls A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...

. Pectin lyase

catalyzes Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycl ...

the following process: :Eliminative cleavage of (1→4)-α-D-alacturonan methyl ester to give oligosaccharides with 4-deoxy-6-''O''-methyl-α,-D-galact-4-enuronosyl groups at their non-reducing ends This enzyme belongs to the family of

lyase In biochemistry, a lyase is an enzyme that catalyzes the breaking (an elimination reaction) of various chemical bond A chemical bond is a lasting attraction between atoms or ions that enables the formation of molecules and crystals. The bon ...

s, specifically those carbon-oxygen lyases acting on polysaccharides.

Nomenclature

The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ...

of this enzyme class is (1→4)-6-''O''-methyl-α-D-galacturonan lyase. Other names in common use include: * endo-pectin lyase, * pectin methyltranseliminase, * pectin trans-eliminase, * pectolyase, * PL, * PMGL, * PNL, and * polymethylgalacturonic transeliminase.

Structural studies

As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and .

Biotechnology applications

Pectin lyases are the only known pectinases capable of degrading highly esterified pectins (like those found in fruits) into small molecules via β-elimination mechanism without producing methanol (which is toxic), in contrast with the combination of PG and PE, which are normally found in commercial products. In addition, the presence of undesirable enzymatic activity in commercial pectinases may be detrimental to aroma because they are responsible for producing unpleasant volatile off flavour. There are many reports of fruit juice clarification by pectin lyases. The alkaline pectinase is inappropriate for use in the food industry due to the acidic pH of fruit juices. However, they have a very high demand in the textile industries. They are used for retting of plant fibers such as

ramie Ramie (pronounced: , ; from Malay ) is a flowering plant in the nettle family Urticaceae, native to eastern Asia. It is a herbaceous perennial growing to tall;

sunn hemp ''Crotalaria juncea'', known as brown hemp, Indian hemp, Madras hemp, or sunn hemp, is a tropical Asian plant of the legume family (Fabaceae). It is generally considered to have originated in India.Heuzé V., Thiollet H., Tran G., Lebas F., 201 ...

jute Jute is a long, soft, shiny bast fiber that can be spun into coarse, strong threads. It is produced from flowering plants in the genus ''Corchorus'', which is in the mallow family Malvaceae. The primary source of the fiber is ''Corchorus olit ...

flax Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known i ...

and hemp. The first report on retting of sunn hemp (Crotalaria juncea) by pectin lyase produced by ''Aspergillus flavus'' MTCC 7589 was published in 2008 but this aspect of pectin lyases needs to be extensively investigated further.

Nomenclature

Structural studies

Biotechnology applications

References

Further reading