Proline is an α-amino acid with the chemical formula HO₂CCH(NH[CH₂)₃]. L-Proline is one of the twenty DNA-encoded amino acids. Its three letter code is pro, its one letter code is P, and its codons are CCU, CCC, CCA, and CCG. It is not an essential amino acid, which means that humans can synthesise it. It is the unique proteogenic amino acid where the α-amino group is secondary. The acid dissociation constant (Ka), also known as the acidity constant or the acid-ionization constant, is a specific equilibrium constant for the reaction of an acid with its conjugate base in aqueous solution [1]. // When an acid dissolves in water, it partly dissociates forming hydronium ions and its conjugate... Physical properties Hazard properties Chemical properties Pharmacological properties OrganicBox_complete a  205-702-2 EINECS for Proline a  PubChem 6148988 a  PubChem 6137 Category: ... Physical properties Hazard properties Chemical properties Pharmacological properties OrganicBox_complete a  205-702-2 EINECS for Proline a  PubChem 6148988 a  PubChem 6137 Category: ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... Physical properties Hazard properties Chemical properties Pharmacological properties OrganicBox_complete a  205-702-2 EINECS for Proline a  PubChem 6148988 a  PubChem 6137 Category: ... Physical properties Hazard properties Chemical properties Pharmacological properties OrganicBox_complete a  205-702-2 EINECS for Proline a  PubChem 6148988 a  PubChem 6137 Category: ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the IR region of the EM spectrum. ... It has been suggested that NMR Data Processing be merged into this article or section. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or informally, mass-spec and MS) is an analytical technique used to measure the mass-to-charge ratio of ions. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... Phenylalanine is one of the standard amino acids. ... This article or section does not cite any references or sources. ... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... An essential amino acid or indispensable amino acid, is an amino acid that cannot be synthesized de novo by the organism (usually referring to humans), and therefore must be supplied in the diet. ... It has been suggested that this article or section be merged into Secondary amine. ...

Biosynthesis

Proline is biosynthetically derived from the amino acid L-glutamate and its immediate precursor is the imino acid (S)-Δ¹-pyrroline-5-carboxylate (P5C). Enzymes involved in a typical biosynthesis include:^[1] Biosynthesis is a phenomenon where chemical compounds are produced from simpler reagents. ... Glutamate is the anion of glutamic acid. ... In chemistry, an imino acid is any molecule that contains both imino (>C=NH) and carboxyl (-C(=O)-OH) functional groups. ...

1. glutamate kinase (ATP-dependent)
2. glutamate dehydrogenase (requires NADH or NADPH)
3. pyrroline-5-carboxylate reductase (requires NADH or NADPH)

In biochemistry, a kinase is a type of enzyme that transfers phosphate groups from high-energy donor molecules, such as ATP, to specific target molecules (substrates); the process is termed phosphorylation. ... Glutamate dehydrogenase is an enzyme, present in mitochondria, as are some of the other enzymes required for urea synthesis, that converts glutamate to α-Ketoglutarate, and vice versa. ... A reductase is an enzyme which lowers the activation energy for a reduction reaction. ...

Structural properties

The distinctive cyclic structure of proline's side chain locks its φ backbone dihedral angle at approximately -75°, giving proline an exceptional conformational rigidity compared to other amino acids. Hence, proline loses less conformational entropy upon folding, which may account for its higher prevalence in the proteins of thermophilic organisms. Proline acts as a structural disruptor in the middle of regular secondary structure elements such as alpha helices and beta sheets; however, proline is commonly found as the first residue of an alpha helix and also in the edge strands of beta sheets. Proline is also commonly found in turns, which may account for the curious fact that proline is usually solvent-exposed, despite having a completely aliphatic side chain. Because proline lacks a hydrogen on the amide group, it cannot act as a hydrogen bond donor, only as a hydrogen bond acceptor. In Aerospace engineering, the dihedral is the angle that the two wings make with each other. ... A representation of the 3D structure of the Myoglobin protein. ... Side view of an α-helix of alanine residues in atomic detail. ... Diagram of β-pleated sheet with H-bonding between protein strands The β sheet (also β-pleated sheet) is the second form of regular secondary structure in proteins — the first is the alpha helix — consisting of beta strands connected laterally by three or more hydrogen bonds, forming a generally twisted, pleated sheet. ... Side view of an α-helix of alanine residues in atomic detail. ... Diagram of β-pleated sheet with H-bonding between protein strands The β sheet (also β-pleated sheet) is the second form of regular secondary structure in proteins — the first is the alpha helix — consisting of beta strands connected laterally by three or more hydrogen bonds, forming a generally twisted, pleated sheet. ... A turn is an element of secondary structure in proteins. ... In chemistry, non-aromatic and non-cyclic (acyclic) organic compounds are called aliphatic. ... An example of a quadruple hydrogen bond between a self-assembled dimer complex reported by Meijer and coworkers. ... An example of a quadruple hydrogen bond between a self-assembled dimer complex reported by Meijer and coworkers. ...

Multiple prolines and/or hydroxyprolines in a row can create a polyproline helix, the predominant secondary structure in collagen. The hydroxylation of proline by prolyl hydroxylase (or other additions of electron-withdrawing substituents such as fluorine) increases the conformational stability of collagen significantly. Hence, the hydroxylation of proline is a critical biochemical process for maintaining the connective tissue of higher organisms. Severe diseases such as scurvy can result from defects in this hydroxylation, e.g., mutations in the enzyme prolyl hydroxylase or lack of the necessary ascorbate (vitamin C) cofactor. Structure of hydroxyproline 4-Hydroxyproline, or hydroxyproline (C5H9O3N), is an uncommon amino acid, abbreviated as HYP, e. ... In proteins, a left-handed polyproline II helix (PPII, poly-Pro II) is formed when sequential residues all adopt (φ,ψ) backbone dihedral angles of roughly (-75°, 150°) and have trans isomers of their peptide bonds. ... A representation of the 3D structure of the Myoglobin protein. ... Tropocollagen triple helix. ... Prolyl hydroxylase (or procollagen-proline dioxygenase) is an enzyme involved in the production of collagen, acting to hydroxylate proline to hydroxyproline. ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance Yellowish brown gas Atomic mass 18. ... Tropocollagen triple helix. ... Scurvy (N.Lat. ... Hydroxylation is any chemical process that introduces one or more hydroxyl groups (-OH) into a compound (or radical) thereby oxidising it. ... For other uses, see Vitamin C (disambiguation). ...

Sequences of proline and 2-aminoisobutyric acid (Aib) also form a helical turn structure^{[citation needed]}. 2-Aminoisobutyric acid, or α-aminoisobutyric acid (AIB) or α-methylalanine or 2-methylalanine, is an amino acid with the structural formula is H2N-C(CH3)2-COOH. It is contained in some antibiotics of fungal origin, eg. ...

Cis-trans isomerization

Peptide bonds to proline and other N-substituted amino acids (such as sarcosine) are able to populate both the cis and trans isomers. Most peptide bonds prefer overwhelmingly to adopt the trans isomer (typically 99.9% under unstrained conditions), chiefly because the amide hydrogen (trans isomer) offers less steric repulsion to the preceding C^α atom than does the following C^α atom (cis isomer). By contrast, the cis and trans isomers of the X-Pro peptide bond are nearly isosteric (i.e., equally bad energetically); the C^α (cis isomer) and C^δ atoms (trans isomer) of proline are roughly equivalent sterically. Hence, the fraction of X-Pro peptide bonds in the cis isomer under unstrained conditions ranges from 10-40%; the fraction depends slightly on the preceding amino acid X, with aromatic residues favoring the cis isomer slightly. A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ... Sarcosine is N-methyl glycine (H3C-NH-CH2-COOH). ... CIS usually refers to: Commonwealth of Independent States, a modern-day political entity consisting of 11 former Soviet Union Republics CIS is also an acronym for: Canadian Interuniversity Sport Cancer Information Service Carcinoma in situ Centre for Independent Studies Center for Immigration Studies Chinese International School Cisalpino Citizenship & Immigration Services... Trans is a Latin noun or prefix, meaning across, beyond or on the opposite side [of] . It is the opposite of cis, which means on the same side [of]. In chemistry, a double bond (or ring) not subject to free rotation in which the greater radical on both ends is...

Cis-trans proline isomerization is a very slow process that can impede the progress of protein folding by trapping one or more prolines crucial for folding in the nonnative isomer, especially when the native isomer is the rarer cis. All organisms possess prolyl isomerase enzymes to catalyze this isomerization, and some bacteria have specialized prolyl isomerases associated with the ribosome. However, not all prolines are essential for folding, and protein folding may proceed at a normal rate despite having non-native isomers of many X-Pro peptide bonds. In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of chemical bonds between atoms, but in which the atoms are arranged differently (analogous to a chemical anagram). ... Protein folding is the process by which a protein assumes its characteristic functional shape or tertiary structure, also known as the native state. ... Prolyl isomerase (also PPIase) is an enzyme found in both prokaryotes and eukaryotes that interconverts the cis and trans isomers of peptide bonds with the amino acid proline. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ...

Usage

Proline and its derivatives are often used as asymmetric catalysts in organic reactions. The CBS reduction and proline catalysed aldol condensation are prominent examples. The CBS reduction, in full the Corey-Bakshi-Shibata reduction, is an organic reaction which transforms ketones enantioselectively into alcohols. ... An Aldol condensation is an organic reaction where an enolate ion reacts with a carbonyl compound to form a β-hydroxyaldehyde or β-hydroxyketone followed by dehydration to a conjugated enone. ...

Proline has a sweet flavor with a distinct aftertaste. Proline also causes slight irritation to the tongue like Sichuan Pepper^{[citation needed]}. Sichuan pepper (or Szechuan pepper) is the outer pod of the tiny fruit of a number of species in the genus Zanthoxylum (most commonly Zanthoxylum piperitum, Zanthoxylum simulans, and Zanthoxylum sancho), widely grown and consumed in Asia as a spice. ...

For unknown reasons, L-proline is an ingredient in energy drinks such as "Sobe power fruit punch".^{[citation needed]}

See also

• Collagen
• Polyproline helix
• Peptide bond (for more discussion of cis-trans isomerization)
• For a thorough scientific overview of disorders of proline and hydroxyproline metabolism, one can consult chapter 81 of OMMBID^[2]. For more online resources and references, see inborn errors of metabolism.
  

Tropocollagen triple helix. ... In proteins, a left-handed polyproline II helix (PPII, poly-Pro II) is formed when sequential residues all adopt (φ,ψ) backbone dihedral angles of roughly (-75°, 150°) and have trans isomers of their peptide bonds. ... A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ... Inborn errors of metabolism are a large group of rare but often serious metabolic disorders that generally arise from deficiency or malfunction of enzymes that regulate conversion of various substances into others. ...

External links

• Proline biosynthesis
• Computational Chemistry Wiki
• Proline biosynthesis
• Links to external chemical sources

References

1. ^ Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISNB 1-57259-153-6.
2. ^ Charles Scriver, Beaudet, A.L., Valle, D., Sly, W.S., Vogelstein, B., Childs, B., Kinzler, K.W. (Accessed 2007). The Online Metabolic and Molecular Bases of Inherited Disease. New York: McGraw-Hill. - Summaries of 255 chapters, full text through many universities. There is also the OMMBID blog.

Charles Robert Scriver (born November 7, 1930) is a Canadian physician and genetics researcher. ... Charles Robert Scriver (born November 7, 1930) is a Canadian physician and genetics researcher. ...