2-Pyrrolidones prolines

This enzyme [EC 3.4.19.3], a member of the C15 peptidase family, is also known as pyroglutamyl-peptidase 1,5-oxoprolyl-peptidase, pyrrolidone-carboxylate peptidase, and pyroglutamyl aminopeptidase. This hydrolase catalyzes the conversion of a 5-oxoprolyl-peptide to produce 5-oxoproline and a peptide. The enzyme will not act on the 5-oxoprolyl peptide if the adjacent amino acid is l-proline. Enzyme activity is inhibited by thiol-blocking reagents. 

Recently, the reduction of an N-terminal pyrrolidone carboxylic acid residue of proteins with diborane in tetrahydrofuran or tetramethyl urea was attempted with some success the N-terminal pyrrolidone carboxylic acid residue may thus be identified by its conversion to proline... 

L-proline is not deteetably hydrolyzed. The enzyme exhibits considerable optical specificity thus, D-pyrrolidone carboxylyl L-alanine is not hydrolyzed while L-pyrrolidone carboxylyl D-alanine is hydrolyzed about 30 times more slowly than the corresponding l-l isomer. 

A study of a Philippines Dysidea sp. has yielded the novel proline analogs of dysidenin, dysideaprolines A-F (950-955) and barbaleucamides A (956) and B (957), which are reminiscent of barbamide (995). Also from the Philippines was isolated the novel pyrrolidone 958 from the nudibranch Asteronotus cespitosus (996), which is the first example of a Dysidea-type polychlorinated metabolite found in a carnivorous mollusc. An Indonesian collection of Dysidea sp. has furnished dysithiazolamide (959), having the suggested absolute configuration shown (997). 

Oxidation of proline and arginine residues leads also to formation of glutamate semialdehyde and, upon its further oxidation, to pyroglutamic acid (A9). Oxidized proline produces also 2-pyrrolidone (K6) (Fig. 5). 

K6. Kato, Y., Uchida, K., and Kawakishi, S., Oxidative fragmentation of collagen and prolyl peptide by Cu(II)/H202. Conversion of proline residue to 2-pyrrolidone. J. Biol. Chem. 267, 23646-23651 (1992). 

Methyl 2-pyrrolidone-5(R)-carboxylate D-Proline, 5-oxo-, methyl ester (10) (64700-65-8)... 

We consider that all of the dolastatins will prove to be of cyanobacterial or other dietary origin. There are some important biosynthetic signatures, for exanqile, which suggest that dolastatin 15 (2) (Figure 1) is most probably derived from L majuscula. These signatures include the presence of the N,N-dimethylvaline residue, a valine-N-methylvaline-proline sequence also found in the microcolins (27, 28) (Figure 7) and the presence of a pyrrolidone ring presumably derived from condensation of phenylalanine and acetate. A... 

Rhodium complexes generated from A-functionalized (S)-proline 3.60 [933, 934, 935] or from methyl 2-pyrrolidone-5-carboxylates 3.61 [936, 937, 938] catalyze the cyclopropanation of alkenes by diazoesters or -ketones. Diastereoisomeric mixtures of Z- and E-cydopropylesters or -ketones are usually formed, but only the Z-esters exhibit an interesting enantioselectivity. However, if intramolecular cyclopropanation of allyl diazoacetates is performed with ligand 3.61, a single isomer is formed with an excellent enantiomeric excess [936,937], The same catalyst also provides satisfactory results in the cyclopropanation of alkynes by menthyl diazoacetate [937, 939] or in the intramolecular insertion of diazoesters into C-H bonds [940]. 

Asymmetric hydrocarboxylation may be applied to the synthesis of chiral A -protected amino carboxylic acids, pyrrolidones or proline precursors. With this synthetic target in mind hydrocarboxylation of/f-substituted A -vinyl- and A -allylphthalimides is catalyzed with palla-dium(ll) chloride in the presence of the chiral phosphanes Diop or DIOCOL28. Although high product selectivities and regioselectivities are achieved, only very low asymmetric inductions are observed (up to 4% ee)28. Until now the best results in a vinyl imide hydrocarboxylation are achieved with, V-vinylsuccinimide in the presence of palladium(II) chloride and (-)-Diop with a 17.1 % ee12. 

Pyrolysis and smoke studies of amino acids indicate that they are potential precursors of several nitrogen heterocyclic ring systems found in tobacco smoke. Proline has been shown to be efficiently converted to pyrrole upon pyrolysis (3219, 3724) and in addition has been proposed as a possible precursor of pyrocoll (2593, 4336). y-Amino acids and dicarboxy-lic amino acids are capable, under pyrolytic conditions, of forming 2-pyrrolidones (1967, 3079) and by a similar mechanism, A-amino acids can form 2-piperidones (1967, 3079). A side effect of the pyrolysis of amino acids is the formation of hydrogen cyanide. 

CAS 98-79-3 EINECS/ELINCS 202-700-3 Synonyms 5-Oxo-L-proline L-Pyroglutamic acid Pyrrolidonecarboxylic acid 2-Pyrrolidone-5-carboxylic acid Ciassification Cyclic organic compd. 

Synonyms 5-Oxo-DL-proline, sodium salt 5-Oxo-L-proline, sodium salt PCA-Na PCA Soda Sodium 5-oxo-L-prolinate Sodium pyroglutamate Sodium DL-2-pyrrolidone-5-carboxylate Sodium L-2-pyrrolidone-5-carboxylate... 

Proline iminopeptidase [L-Prolylpeptide hydrolase] (3.4.11.5) is produced. [Formerly EC3.4.1.4.] Pyroglutamyl aminopeptidase [L-Pyroglutamyl-peptide hydrolase, Pyrrolidone-carboxylate peptidase] (3.4.11.8) is produced. [Removes pyroglutamate from various penultimate amino acid residues except L-proline. Occurs in Pseudomonas, Bacillus subtilis, rat liver.]... 

To preserve beer colloidal stability, brewers usually remove haze-active materials [34]. To get rid of haze-active proteins, precipitation with tannic acid, hydrolysis with papain and adsorption to bentonite [35] or silica gel [36, 37] are very effective, but unfortunately in some cases, such procedures also remove foam proteins. To remove haze-active polyphenols, the most usual way is adsorption to polyvinylpolypyrrolidone-PVPP. Because of the structural analogy between these compounds and proline [38], pyrrolidone rings bind polymerized flavanoids through hydrogen and ionic bonds. 

Method Seven, Signaigo and Adkins (725). Pyrrole + ethyl magnesium bromide + ethyl chlorocarbonate -> 1,2-dicarbethoxypyrrole -> 1,2-di-carbetboxypyrrolidine proline. Adkins and coworkers (45, 653, 724) have shown that the pyrrole nucleus requires more drastic conditions for reduction than the benzenoid nucleus, that the N-carbethoi substituent decreases resonance so that the pyrrole ring may be hydrogenated under mild conditions and that this substituent is more effective in the 1-than the 2-position. The synthesis of proline by the reduction of 2-carboxypyrrole (312, 297, 647) or of 2-carboxy-a-pyrrolidone (294, 539, 540) has not been successful for these reasons. 

The derivatives are used for amino acid analysis via HPLC separation. Instead of mercapto-ethanol, a chiral thiol, e.g., N-isobutyryl-L-cysteine, is used for the detection of D-amino acids. The detection hmit lies at 1 pmol. The very fast racemizing aspartic acid is an especially suitable marker. One disadvantage of the method is that proline and hydroxyproline are not detected. This method is apphed, e.g., in the analysis of fruit juices, in which high concentrations of D-amino acids indicate bacterial contamination or the use of highly concentrated juices. Conversely, too low concentrations of D-amino acids in fermented foods (cheese, soy and fish sauces, wine vinegar) indicate unfermented imitations. Fluorescamine reacts with primary amines and amino acids - at room temperature under alkaline conditions - to form fluorescent pyrrolidones (Aex = 390 nm, Aem - 474 nm). The detection limit lies at 50-100 pmol ... 

Potassium L-tyrosine-O-sulfate dihydrate, 37B, 275 N-Acetyl-L-histidine-N-methylamide, 43B, 600 p-Alanyl-L-histidine, 42B, 359 43B, 601 Cyclo(L-seryl-L-histidyl) monohydrate, 44B, 437 1 -(D-3-Mercapto-2-methylpropionyl)-L-proline, 46B, 478 3-Hydroxy-3-isobutyl-2-pyrrolidone-5-carboxylie acid, 43B,... 

For the synthesis of 2-pyrrolidone III-16, we followed the procedure described by Germanas and coworkers for the enantioselective alkylation of proline [118]. This procedure was based on a method reported by Seebach [119], in which proline is condensed with pivaldehyde to give a single stereoisomer of 2-f-butyl-l-aza-3-oxabicylo[3.3.0]octan-4-one III-42 [120], which is deprotonated with LDA to give a chiral enolate that can be alkylated with an electrophile (Scheme 4.21). 

Proline represents a unique class of molecules among amino acids (Fig. 1). As pointed out by Adams, the inclusion of the a-amino group within a ring structure bestows a number of special properties (1). With its peptide bond within the pyrrolidone ring, proline confers rigidity and three-dimensional stability to proteins. The high content of proline and hy-droxyproline in collagen contributes to the unique physical properties of this structural protein. Less appreciated but perhaps equally important is... 

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