Opines are low molecular weight compounds found in plant crown gall tumors or hairy root tumors produced by pathogenic bacteria of the genus ''

Agrobacterium ''Agrobacterium'' is a genus of Gram-negative bacteria established by H. J. Conn that uses horizontal gene transfer to cause tumors in plants. ''Agrobacterium tumefaciens'' is the most commonly studied species in this genus. ''Agrobacterium'' is ...

'' and '' Rhizobium''. Opine biosynthesis is catalyzed by specific enzymes encoded by genes contained in a small segment of DNA (known as the T-DNA, for 'transfer DNA'), which is part of the Ti plasmid (in ''Agrobacterium'') or Ri plasmid (in ''Rhizobium''), inserted by the bacterium into the plant genome. The opines are used by the bacterium as an important energy, carbon and nitrogen source. Each strain of ''

'' and '' Rhizobium'' induces and catabolizes a specific set of opines, this set typifying the Ti plasmid and Ri plasmid. There are some 30 different opines described so far. Synthesis opines

Chemical structure

Chemically, opines fall into two major structural classes: nopaline

1. The vast majority are secondary amine derivatives resulting from the reduction of the imine formed by condensation of an amino acid, either with a keto acid or a

sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...

. The first subcategory includes the opines from the

nopaline Nopaline is a chemical compound derived from the amino acids glutamic acid and arginine. It is classified as an opine. Ti plasmids are classified on the basis of the different types of opines they produce. These may be nopaline plasmids, oct ...

and

octopine Octopine is a derivative of the amino acids arginine and alanine. It was the first member of the class of chemical compounds known as opines to be discovered. Octopine gets its name from '' Octopus octopodia'' from which it was first isolated i ...

families. The nopaline family (nopaline, nopalinic acid, leucinopine, glutaminopine, succinamopine) is formed when alpha-ketoglutarate serves as the keto substrate in the condensation reaction. The octopine family (octopine, octopinic acid, lysopine, histopine) is formed when

pyruvate Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is an intermediate in several metabolic pathways throughout the cell. Pyruvic aci ...

is involved in the condensation reaction.

The second subcategory includes the mannityl family (mannopine, mannopinic acid, agropine, agropinic acid) and the chrysopine family (deoxy-fructosyl glutamate, deoxy-fructosyl glutamine, deoxy-fructosyl oxoproline and chrysopine) formed by the condensation of an amino-acid with mannose. 2. Agrocinopines form a small, separate class of opines. Chemically they are sugar-phosphodiesters. For example, agrocinopine A is a phosphodiester of

sucrose Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refined ...

and L-

arabinose Arabinose is an aldopentose – a monosaccharide containing five carbon atoms, and including an aldehyde (CHO) functional group. For biosynthetic reasons, most saccharides are almost always more abundant in nature as the "D"-form, or structurally ...

Nomenclature

The name ''opine'' comes from ''octopine'', the first opine discovered in 1927, not in crown galls, but in

octopus An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...

muscle. ''Nopaline'' comes from the identification of this molecule in tumors that appeared on "nopal", the Spanish and French names of ''

Opuntia ''Opuntia'', commonly called prickly pear or pear cactus, is a genus of flowering plants in the cactus family Cactaceae. Prickly pears are also known as ''tuna'' (fruit), ''sabra'', ''nopal'' (paddle, plural ''nopales'') from the Nahuatl word f ...

'' spp. cactus. According to '' Oxford English Dictionary'', the word ''opine'' was first used in print in 1977. Usually, the name of newly discovered opines has the ending "-opine". Exceptions are nopaline and strombine. On the other hand, not all molecule names ending in "-opine" are opines. For example,

atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given i ...

, stylopine, europine, and lycopine belong to different classes of molecules.

Other sources of opines

Opines and opine-like substances are not restricted to crown galls tumors. The very first opine discovered, octopine, was initially isolated from octopus muscle. Similar derivatives have been isolated from muscle tissue of certain marine invertebrates: alanopine, strombine, and tauropine. Opines like acetopine and nopaline can also be formed in normal callus and plant tissue as a result of

arginine Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the am ...

metabolism.

Saccharopine Saccharopine is an intermediate in the metabolism of amino acid lysine. It is a precursor of lysine in the alpha-aminoadipate pathway which occurs in fungi and euglenids. In mammals and higher plants saccharopine is an intermediate in the degrad ...

is an intermediate in the metabolism of amino acid

lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. It contains an α-amino group (which is in the protonated form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −C ...

and occurs in fungi, higher plants and mammals, including man. The poisonous mushroom ''

Clitocybe acromelalga ''Paralepistopsis acromelalga'' is a basidiomycete fungus in the Tricholomataceae family. It was formerly classified as ''Clitocybe'' ''acromelalga''. Taxonomy It was first described in 1918 by the mycologist T. Ichimura and classified as ''C ...

'' is a source of four opine type amino acids: valinopine, epileucinopine, isoleucinopine and phenylalaninopine.

List of opines

This is an alphabetical list of some opines or opine-like compounds. ;Acetopine Acetopine (''N''²-(carboxymethyl)-arginine or demethyl-octopine) was isolated from cotton (''Gossypium hirsutum'') and soybean (''Glycine max'') callus. It wasn't found in plant tissues transformed by ''Agrobacterium'' and therefore it is not considered a "true" opine. ;Agrocinopines Agrocinopines (A-D) are a separate class of opines. They are sugar-phosphodiesters. Agrocinopine A is phosphodiester of sucrose and L-Arabinose. Agrocinopine B is the corresponding phosphodiester, in which the glucose has been hydrolyzed from the sucrose portion of agrocinopine A. ;Agropine Agropine (1'-deoxy-D-mannitol-1'-yl)-L-glutamine,1',2'-lactone) was obtained from crown gall tumors. It is a member of the mannityl family. It is derived from mannopine through the formation of a lactone. ;Agropinic acid Agropinic acid (''N''-1-(D-mannityl)-L-glutamic acid lactam) is produced by crown gall tumors. Belongs to the mannityl family. It is formed by

lactamization A lactam is a cyclic amide, formally derived from an amino alkanoic acid. The term is a portmanteau of the words ''lactone'' + ''amide''. Nomenclature Greek prefixes in alphabetical order indicate ring size: * α-Lactam (3-atom rings) * β-Lacta ...

of agropine. ;Alanopine Beta-alanopine (2,2'-iminodipropionic acid or L-alanine, ''N''-(1-carboxyethyl)-) and ''meso''-alanopine (meso-''N''-(1-carboxyethyl)-alanine) were isolated from marine invertebrates. Structurally it is a member of the octopine family. ;Asparaginopine See ''succinamopine'' ;Chrysopine Chrysopine (d-lactone of ''N''-1-deoxy-D-fructosyl-L-glutamine) was first obtained from

fig tree ''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending int ...

and

chrysanthemum Chrysanthemums (), sometimes called mums or chrysanths, are flowering plants of the genus ''Chrysanthemum'' in the family Asteraceae. They are native to East Asia and northeastern Europe. Most species originate from East Asia and the center ...

crown gall tumors. It is the deoxyfructosyl analog of agropine. ;Cucumopine Cucumopine (4,6-dicarboxy-4,5,6,7-tetrahydro-1''H''-imidazo ,5-''c''yridine-4-propanoic acid) was found in grapevine crown gall tumours and carrot hairy-root cultures. ;Epileucinopine Epileucinopine (''N''-(1-carboxy-3-methylbutyl)glutamic acid or ''N''²-(1,3-dicarboxypropyl)leucine) was isolated from the poisonous mushroom ''Clitocybe acromelalga''. ;Glutaminopine Glutaminopine (''N''²-(D-1,3-dicarboxypropyl) derivative of glutamine) is a member of the nopaline family isolated from crown gall tumors. ;Heliopine Heliopine (also named vitopine) (''N''² -(1-carboxyethyl)glutamine) was obtained from crown gall tumors. ;Histopine Histopine (''N''-(D-1-carboxyethyl)histidine) is a member of the octopine family found in crown gall tumors. ;Isoleucinopine Isoleucinopine (''N''-(1-carboxy-2-methylbutyl)glutamic acid or ''N''-(1,3-dicarboxypropyl)isoleucine) was isolated from the poisonous mushroom ''Clitocybe acromelalga''. ;Leucinopine Leucinopine (''N''²-(D-1,3-dicarboxypropyl) derivative of leucine) is a member of the nopaline family isolated from crown gall tumors. ;Lysopine Lysopine (''N''²-(D-1-carboxyethyl)-L-lysine) is a member of the octopine family found in crown gall tumors. ;Mannopine Mannopine (''N''-1-(D-mannityl)-L-glutamine) is found in crown gall tumors. It is the head member of the mannityl family of opines. ;Mannopinic acid Mannopinic acid (''N''-1-(D-mannityl)-L-glutamic acid) was isolated from crown gall tumors. Belongs to the mannityl family. ;Methiopine Methiopine (''N''- -D-(carboxyl)ethylL-methionine) was found in crown gall tumors. ;Mikimopine Mikimopine (4-epimer of cucumopine) was first isolated from tobacco crow gall tumors. ;

Nopaline Nopaline is a chemical compound derived from the amino acids glutamic acid and arginine. It is classified as an opine. Ti plasmids are classified on the basis of the different types of opines they produce. These may be nopaline plasmids, oct ...

Nopaline (''N''²-(D-1,3-dicarboxypropyl)-L-arginine) was first isolated from crown gall tumors. It is the head member of the nopaline family of opines. It was also found in certain nontransformed plant tissues as a result of arginine metabolism ;Nopalinic acid Nopalinic acid (also named ornaline) (''N''²-(D-1,3-dicarboxypropyl)-L-ornithine) is a member of the nopaline family found in crown gall tumors. ;

Octopine Octopine is a derivative of the amino acids arginine and alanine. It was the first member of the class of chemical compounds known as opines to be discovered. Octopine gets its name from '' Octopus octopodia'' from which it was first isolated i ...

Octopine (''N''²-(D-1-carboxyethyl)-L-arginine) is the first opine discovered in 1927 in

muscle and later in crown gall tumors. It is also found in other cephalopod species and lamellibranchs. It is the head member of the octopine family of opines. ;Octopinic acid Octopinic acid (''N''²-(D-1-carboxyethyl)-L-ornithine) is a member of the octopine family isolated from crown gall tumors. ;Ornaline See ''nopalinic acid'' ;Phenylalaninopine Phenylalaninopine (''N''-(1-carboxy-2-phenylethyl)glutamic acid) was isolated from the poisonous mushroom ''Clitocybe acromelalga''. ;Rideopine Rideopine (''N''-(4'-aminobutyl)-D-glutamic acid) is an opine-like molecule derived from putrescine. It is obtained from crown gall tumors. ;

Although not found in crown gall tumors, saccharopine (epsilon-''N''-(L-glutar-2-yl)-L-lysine) is chemically similar to "true" opines. It is formed by condensation of lysine and alpha-ketoglutarate. Saccharopine is an intermediate in the metabolism of amino acid lysine and occurs in fungi, higher plants and mammals, including man. ;Santhopine Santhopine is the deoxyfructosyl analog of mannopine. It is a naturally occurring compound found in rotting fruits and vegetables. It was also isolated from crown gall tumors. ;Strombine Strombine (Methylimidodiacetic acid or ''N''-(D-1-carboxyethyl)-glycine) was first isolated from the

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk ''Strombus''. It acts as a fish attractant. Structurally it is a member of the octopine family. ;Succinamopine Succinamopine (also named asparaginopine) (''N''-(3-amino-1-carboxy-3-oxopropyl)glutamic acid) is a member of the nopaline family isolated from crown gall tumors. Its structure is analogous to that of nopaline, with asparagine replacing arginine. ;Tauropine Tauropine (''N''-(D-1-carboxyethyl)-taurine) was found in some marine invertebrates. It is also called rhodoic acid. Structurally it is a member of the octopine family. ;Valinopine Valinopine (''N''-(1-carboxy-2-methylpropyl)glutamic acid or ''N''-(1,3-dicarboxypropyl)valine) was isolated from the poisonous mushroom ''Clitocybe acromelalga''. ;Vitopine See ''heliopine''

References

{{reflist Amino acid derivatives