Imino acid

Last updated
1-Pyrroline-5-carboxylic acid, an N-substituted imino acid Delta-1-pyrroline-5-carboxylic acid.svg
1-Pyrroline-5-carboxylic acid, an N-substituted imino acid

In organic chemistry, an imino acid is any molecule that contains both imine (>C=NH) and carboxyl (-C(=O)-OH) functional groups. [1]

Contents

Imine-(primary)-skeletal.svg
Imino group attached to carbon
The two functional groups that together define an imino acid

Imino acids are structurally related to amino acids, which have amino group instead of imine—a difference of single vs double-bond between nitrogen and carbon. The simplest example is dehydroglycine.

D-Amino acid oxidase is an enzyme that is able to convert amino acids into imino acids. Also the direct biosynthetic precursor to the amino acid proline is the imino acid (S)-Δ1-pyrroline-5-carboxylate (P5C).

proline L-proline-skeletal.png
proline

Secondary amino acids, amino acids containing a secondary amine group are sometimes named imino acids, [2] [3] though this usage is obsolescent. [1] The only proteinogenic amino acid of this type is proline, although the related non-proteinogenic amino acids hydroxyproline [4] [5] [6] and pipecolic acid [7] have often been included in studies of this class of compounds.

The term imino acid is also the obsolete term for imidic acids , structures containing the -C(=NH)-OH group, and should not be used for them. [1]

Related Research Articles

Amino acid Organic compounds containing amine and carboxylic groups

Amino acids are organic compounds that contain amino and carboxylic acid functional groups, along with a side chain specific to each amino acid. The elements present in every amino acid are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) (CHON); in addition sulfur (S) is present in the side chains of cysteine and methionine, and selenium (Se) in the less common amino acid selenocysteine. More than 500 naturally occurring amino acids are known to constitute monomer units of peptides, including proteins, as of 2020 although only 22 appear in the genetic code, 20 of which have their own designated codons and 2 of which have special coding mechanisms: Selenocysteine which is present in all eukaryotes and pyrrolysine which is present in some prokaryotes.

Collagen helix A structure in biochemistry

The collagen triple helix or type-2 helix is the primary secondary structure of various types of fibrous collagen, including type I collagen. It consists of a triple helix made of the repetitious amino acid sequence glycine-X-Y, where X and Y are frequently proline or hydroxyproline. Collagen folded into a triple helix is known as tropocollagen. Collagen triple helices are often bundled into fibrils which themselves form larger fibres, as in tendon.

In chemistry, a zwitterion, also called an inner salt or dipolar ion, is a molecule that contains an equal number of positively- and negatively-charged functional groups. With amino acids, for example, in solution a chemical equilibrium will be established between the "parent" molecule and the zwitterion.

Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group -NH
2
but is rather a secondary amine. The secondary amine nitrogen is in the protonated form (NH2+) under biological conditions, while the carboxyl group is in the deprotonated −COO form. The "side chain" from the α carbon connects to the nitrogen forming a pyrrolidine loop, classifying it as a aliphatic amino acid. It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid L-glutamate. It is encoded by all the codons starting with CC (CCU, CCC, CCA, and CCG).

Hydroxyproline Chemical compound

(2S,4R)-4-Hydroxyproline, or L-hydroxyproline (C5H9O3N), is an amino acid, abbreviated as Hyp or O, e.g., in Protein Data Bank.

<i>N</i>-Methyl-<small>D</small>-aspartic acid Amino acid derivative

N-methyl-D-aspartic acid or N-methyl-D-aspartate (NMDA) is an amino acid derivative that acts as a specific agonist at the NMDA receptor mimicking the action of glutamate, the neurotransmitter which normally acts at that receptor. Unlike glutamate, NMDA only binds to and regulates the NMDA receptor and has no effect on other glutamate receptors. NMDA receptors are particularly important when they become overactive during, for example, withdrawal from alcohol as this causes symptoms such as agitation and, sometimes, epileptiform seizures.

In chemistry, hydroxylation can refer to:

Proteinogenic amino acid Amino acid that is incorporated biosynthetically into proteins during translation

Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino acids, 20 in the standard genetic code and an additional 2 that can be incorporated by special translation mechanisms.

Imine Chemical compound

An imine is a functional group or organic compound containing a carbon–nitrogen double bond. The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bonds. Imines are common in synthetic and naturally occurring compounds and they participate in many reactions.

Coomassie brilliant blue Chemical compound

Coomassie brilliant blue is the name of two similar triphenylmethane dyes that were developed for use in the textile industry but are now commonly used for staining proteins in analytical biochemistry. Coomassie brilliant blue G-250 differs from Coomassie brilliant blue R-250 by the addition of two methyl groups. The name "Coomassie" is a registered trademark of Imperial Chemical Industries.

Cyanogen bromide is the inorganic compound with the formula (CN)Br or BrCN. It is a colorless solid that is widely used to modify biopolymers, fragment proteins and peptides, and synthesize other compounds. The compound is classified as a pseudohalogen.

1-Pyrroline-5-carboxylic acid Chemical compound

1-Pyrroline-5-carboxylic acid is a cyclic imino acid. Its conjugate base and anion is 1-pyrroline-5-carboxylate (P5C). In solution, P5C is in spontaneous equilibrium with glutamate-5-semialdhyde (GSA). The stereoisomer (S)-1-pyrroline-5-carboxylate is an intermediate metabolite in the biosynthesis and degradation of proline and arginine.

Procollagen-proline dioxygenase

Procollagen-proline dioxygenase, commonly known as prolyl hydroxylase, is a member of the class of enzymes known as alpha-ketoglutarate-dependent hydroxylases. These enzymes catalyze the incorporation of oxygen into organic substrates through a mechanism that requires alpha-Ketoglutaric acid, Fe2+, and ascorbate. This particular enzyme catalyzes the formation of (2S, 4R)-4-hydroxyproline, a compound that represents the most prevalent post-translational modification in the human proteome.

The discovery of an orally inactive peptide from snake venom established the important role of angiotensin converting enzyme (ACE) inhibitors in regulating blood pressure. This led to the development of Captopril, the first ACE inhibitor. When the adverse effects of Captopril became apparent new derivates were designed. Then after the discovery of two active sites of ACE: N-domain and C-domain, the development of domain-specific ACE inhibitors began.

Alkanolamine Class of chemical compounds

Alkanolamines are chemical compounds that contain both hydroxyl (-OH) and amino (-NH2, -NHR, and -NR2) functional groups on an alkane backbone. The term alkanolamine is a broad class term that is sometimes used as a subclassification.

Iminoglycinuria Medical condition

Iminoglycinuria is an autosomal recessive disorder of renal tubular transport affecting reabsorption of the amino acid glycine, and the imino acids proline and hydroxyproline. This results in excess urinary excretion of all three acids.

The imine Diels–Alder reaction involves the transformation of all-carbon dienes and imine dienophiles into tetrahydropyridines.

Non-proteinogenic amino acids Are not naturally encoded in the genome

In biochemistry, non-coded or non-proteinogenic amino acids are distinct from the 22 proteinogenic amino acids which are naturally encoded in the genome of organisms for the assembly of proteins. However, over 140 non-proteinogenic amino acids occur naturally in proteins and thousands more may occur in nature or be synthesized in the laboratory. Many non-proteinogenic amino acids are important:

Clostridial aminopeptidase is an enzyme. This enzyme catalyses the following chemical reaction

Secondary amino acids are amino acids which do not contain the amino group -NH
2
but is rather a secondary amine. Secondary amino acids can be classified to cyclic acids such as proline and acyclic N-substituted amino acids.

References

  1. 1 2 3 IUPAC , Compendium of Chemical Terminology , 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006) " Imino acids ". doi : 10.1351/goldbook.I02959
  2. Proline at the US National Library of Medicine Medical Subject Headings (MeSH)
  3. "III. Amino Acids". Oklahoma State University. Archived from the original on 2008-01-18. Retrieved 2015-01-03.
  4. Myhill, D.; Jackson, D.S. (1963). "Separation of proline and hydroxyproline using thin-layer chromatography". Analytical Biochemistry. 6 (2): 193–198. doi:10.1016/0003-2697(63)90110-6. PMID   14061301.
  5. Stout, E.R.; Fritz, G.J. (1966). "Role of Oxygen Fixation in Hydroxyproline Biosynthesis by Etiolated Seedlings". Plant Physiology. 41 (2): 197–202. doi:10.1104/pp.41.2.197. PMID   16656240.
  6. Blumenkrantz, N.; Asboe-Hansen, G. (1975). "An assay for hydroxyproline and proline on one sample and a simplified method for hydroxyproline". Analytical Biochemistry. 63 (2): 331–340. doi:10.1016/0003-2697(75)90354-1. PMID   1122021.
  7. Maruyama, S; Miyoshi, S; Nomura, G; Suzuki, M; Tanaka, H; Maeda, H (1993). "Specificity for various imino-acid-residues of a proline-specific dipeptidylcarboxypeptidase from a Streptomyces species". Biochim Biophys Acta. 1162 (1–2): 72–76. doi:10.1016/0167-4838(93)90129-f. PMID   8448197.