Opines are low molecular weight compounds found in plant crown gall tumors or hairy root tumors produced by parasitic bacteria of the genus Agrobacterium. 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, inserted by the bacterium into the plant genome. The opines are used by the bacterium as an important source of nitrogen and energy. Each strain of Agrobacterium induces and catabolizes a specific set of opines. There are at least 30 different opines described so far.
Chemically, opines fall into two major structural classes:
1. The vast majority are secondary amine derivatives formed by condensation of an amino acid, either with a keto acid or a sugar. The first subcategory includes the nopaline and octopine 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 is involved in the condensation reaction.
The second subcategory includes the mannityl family (mannopine, mannopinic acid, agropine, agropinic acid) formed by the condensation of an amino-acid with mannose.
The name opine comes from octopine, the first opine discovered in 1927, not in crown galls, but in octopus muscle. 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, 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 metabolism. Saccharopine is an intermediate in the metabolism of amino acid lysine and occurs in fungi, higher plants and mammals, including man. The poisonous mushroom Clitocybe acromelalga 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 (N2-(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 (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 (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 of agropine.
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.
Cucumopine (4,6-Dicarboxy-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-4-propanoic acid) was found in grapevine crown gall tumours and carrot hairy-root cultures.
Epileucinopine (N-(1-Carboxy-3-methylbutyl)glutamic acid or N2-(1,3-Dicarboxypropyl)leucine) was isolated from the poisonous mushroom Clitocybe acromelalga.
Glutaminopine (N2-(D-1,3-dicarboxypropyl) derivative of glutamine) is a member of the nopaline family isolated from crown gall tumors.
Heliopine (also named vitopine) (N2 -(1-Carboxyethyl)glutamine) was obtained from crown gall tumors.
Histopine (N-(D-1-carboxyethyl)histidine) is a member of the octopine family found in crown gall tumors.
Isoleucinopine (N-(1-Carboxy-2-methylbutyl)glutamic acid or N-(1,3-Dicarboxypropyl)isoleucine) was isolated from the poisonous mushroom Clitocybe acromelalga.
Leucinopine (N2-(D-1,3-dicarboxypropyl) derivative of leucine) is a member of the nopaline family isolated from crown gall tumors.
Lysopine (N2-(D-l-carboxyethyl)-L-lysine) is a member of the octopine family found in crown gall tumors.
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 (N-[1-D-(carboxyl)ethyl]-L-methionine) was found in crown gall tumors.
Mikimopine (4-Epimer of cucumopine) was first isolated from tobacco crow gall tumors.
Nopaline (N2-(~-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) (N2-(~-1,3-dicarboxypropy1)-L-ornithine) is a member of the nopaline family found in crown gall tumors.
Octopine (N2-(D-l-carboxyethyl)-L-arginine) is the first opine discovered in 1927 in octopus 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 (N2-(D-l-carboxyethyl)-L-ornithine) is a member of the octopine family isolated from crown gall tumors.
See nopalinic acid
Phenylalaninopine (N-(1-Carboxy-2-phenylethyl)glutamic acid) was isolated from the poisonous mushroom Clitocybe acromelalga.
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 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 (Methylimidodiacetic acid or N-(D-1-carboxyethyl)-glycine) was first isolated from the gastropod mollusk Strombus. It acts as a fish attractant. Structurally it is a member of the octopine family.
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 (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 (N-(1-Carboxy-2-methylpropyl)glutamic acid or N-(1,3-Dicarboxypropyl)valine) was isolated from the poisonous mushroom Clitocybe acromelalga.
- Moore, Larry W.; Chilton, William Scott; Canfield, Marilyn L. (1997). "Diversity of opines and opine-catabolizing bacteria isolated from naturally occurring crown gall tumors". Applied and Environmental Microbiology 63 (1): 201–207.