Nepenthesin (also spelled nepenthacin or nepenthasin) is an

aspartic protease Aspartic proteases are a catalytic type of protease enzymes that use an activated water molecule bound to one or more aspartate residues for catalysis of their peptide substrates. In general, they have two highly conserved aspartates in the activ ...

of plant origin that has so far been identified in the

pitcher In baseball, the pitcher is the player who throws ("pitches") the baseball from the pitcher's mound toward the catcher to begin each play, with the goal of retiring a batter, who attempts to either make contact with the pitched ball or draw ...

secretions of '' Nepenthes'' and in the leaves of ''

Drosera peltata ''Drosera peltata'', commonly called the shield sundewSalmon, Bruce. 2001. ''Carnivorous Plants of New Zealand''. Ecosphere Publications. or pale sundew,Erickson, Rica. 1968. ''Plants of Prey in Australia''. Lamb Paterson Pty. Ltd.: Osborne Park, ...

''. It is similar to

pepsin Pepsin is an endopeptidase that breaks down proteins into smaller peptides. It is produced in the gastric chief cells of the stomach lining and is one of the main digestive enzymes in the digestive systems of humans and many other animals, w ...

, but differs in that it also cleaves on either side of Asp residues and at Lys┼ Arg. While more pH and temperature stable than

porcine The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus ...

pepsin A, it is considerably less stable in

urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important ...

or guanidine hydrochloride. It is the only known protein with such a stability profile. The name ''nepenthesin'' was coined in 1968 by Shigeru Nakayama and Shizuko Amagase. Alternative names for this enzyme include ''Nepenthes'' acid proteinase and ''Nepenthes'' aspartic proteinase. Two

isozyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. dif ...

s have been identified in ''Nepenthes'': nepenthesin I and nepenthesin II. The production of large quantities of nepenthesin-1 through

heterologous expression Heterologous expression refers to the expression of a gene or part of a gene in a host organism that does not naturally have the gene or gene fragment in question. Insertion of the gene in the heterologous host is performed by recombinant DNA techno ...

in ''

Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...

'' was described in 2014. The names cephalotusin, dionaeasin and droserasin have been proposed for similar aspartic endopeptidases originating from the carnivorous plant genera ''

Cephalotus ''Cephalotus'' ( or ; Greek: ''κεφαλή'' "head", and ''οὔς''/''ὠτός'' "ear", to describe the head of the anthers) is a genus which contains one species, ''Cephalotus follicularis'' the Albany pitcher plant, a small carnivorous pi ...

'', '' Dionaea'' and ''

Drosera ''Drosera'', which is commonly known as the sundews, is one of the largest genera of carnivorous plants, with at least 194 species. 2 volumes. These members of the family Droseraceae lure, capture, and digest insects using stalked mucilaginou ...

'', respectively.

Discovery

In the late 19th century,

Sydney Howard Vines Sydney Howard Vines Royal Society, FRS (31 December 1849 – 4 April 1934) was a British botanist and academic. He was Sherardian Professor of Botany at Oxford University from 1888 to 1919, and served as President of the Linnean Society of London ...

showed that the pitcher fluid from ''Nepenthes'' could digest protein in acidic conditions. He suggested the plants were making a digestive enzyme, for which he proposed the name "nepenthin". In the late 1960s, Josef Weigl's group in Germany and Shizuko Amagase's group in Japan each used

chromatography In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system ( ...

to purify the proteolytic activity from several ''Nepenthes'' species, finding it to be most active at pH 2–3. Amagase and Shigeru Nakayama proposed the name "Nepenthesin" for the responsible protease(s). In 1998, Kenji Takahashi's group purified protein from 30 liters of '' Nepenthesia distillatoria'' fluid, finding activity similar to that previously described, and reporting part of the nepenthesin amino acid sequence.

References

External links

* The

MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibit ...

online database for peptidases and their inhibitors
A01.040
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