Proline isolation

The synthesis starts with the preparation of diethyl (2-cyanoethyl)malonate (Expt 5.161) by the Michael addition of diethyl malonate to acrylonitrile. Hydrogenation over Raney nickel converts the cyanoethyl compound to the corresponding primary amine (41) which is converted into proline (isolated initially as the hydrochloride) by the reaction sequence shown. Liberation of the free amino acid from its salt is achieved in this case by treatment with triethyl-amine (cf. serine, Expt 5.183). 

As indicated in Figure 2, when minces of tumor obtained from normal and ascorbic acid-deficient animals were incubated with C14-pro-line, much more radioactivity was incorporated into the collagen of the normal tissue. When the specific radioactivities of the isolated imino acids were examined (Table HI), several conclusions were possible. In the experiments with granuloma from normal animals and C14-proline, the values for hydroxyproline were not far from those of proline. With the scorbutic granulomas, the specific activity of the isolated proline was not greatly reduced, compared to that obtained from the normal granuloma. In contrast, the specific activity of the hydroxyproline isolated from the deficient tissues was markedly reduced. Similar results were obtained in the studies with tritiated proline. Thus, the specific activity of the proline isolated from the deficient granuloma was only moderately reduced, whereas the specific activity of the hydroxyproline was extremely low. This observation may be explained in terms of a dual-pathway mechanism of proline incorporation, considered below. 

L-Proline. D,L-proline was synthesized before its discovery in proteins by R. Willstatter, L-proline isolated from acid-hydrolyzate of casein by E. Fischer, 1901. Name from p(yr) roli (di) ne-carboxylic acid. 

Isolated yield when the reaction was carried out in the presence of L-proline isolated yield of 128d = 42 %... 

An amino acid having the constitution shown has been isolated from horse chestnuts. It is configurationally related to L-proline and has the R configxuation at C-3. Write a stereochemically correct representation for this compoimd. 

Azetidine-2-carboxylic acid, the lower homolog of proline, has been isolated from Convallaria majalis (lily of the valley) 40,44), Polygonatum officinalis (Solomon s seal) 153), and Polygonatum multiflorum 45). Fowden and Steward 47) surveyed plants from 56 genera for nitrogenous compounds and found azetidine-2 -carboxylic acid to be restricted to members of the Liliaceae. In some species it was identified in leaf, stem, and root but was more commonly found in the seed. In Polygonatum, azetidine-2-carboxylic acid accounted for 75% or more of the total nonprotein nitrogen in the rhizome 45). There was no evidence that it occurred as a constituent of protein. 

The literature is less extensive on the use of protoplasts in stress-tolerance investigations however, some applications have been attempted. For example, in one study protoplasts were isolated from the leaves of a wild relative of tomato shown to be salt tolerant and from a salt-sensitive, cultivated species (Rosen Tal, 1981). In the presence of NaCI the plating efficiency (number of surviving cells/number of cells applied to the plate) of the wild relative was greater than the cultivated, sensitive cultivar. Proline, when added to the culture media, was found to enhance the plating efficiency of the salt-sensitive cultivar but not the wild, salt-tolerant relative. These results suggest that traits related to salt tolerance are expressed by the isolated protoplasts and that the response of protoplasts to environmental stress can be manipulated, i.e. the proline response. 

Rosen, A. Tal, M. (1981). Salt tolerance in the wild relatives of the cultivated tomato responses of naked protoplasts isolated from leaves of Lycopersicon esculentum and L. peruvianum to NaCl and proline. Zeitschrift fur Pflanzenphy-siologie, 102, 91-4. 

The proline-catalyzed reaction has been extend to the reaction of propanal, butanal, and pentanal with a number of aromatic aldehydes and proceeds with high syn selectivity.197 The reaction can also be carried out under conditions in which the imine is formed in situ. Under these conditions, the conjugative stabilization of the aryl imines leads to the preference for the aryl imine to act as the electrophile. A good yield of the expected P-aminoalcohol was obtained with propanal serving as both the nucleophilic and the electrophilic component. The product was isolated as a 7-amino alcohol after reduction with NaBH4. 

This reaction was applied to L-proline ethyl ester (R = H), and two diastere-omers were isolated, each diastereomer being a mixture of stereoisomers (E/Z) related to the oximino group. Attempts to completely separate these isomers failed. The oximino group of the product (462a) was removed by a CH2O/HCI mixture. As a result, hydrated aldehyde hydrochloride (463a) was obtained. It... 

Other workers began to study the structure of gramicidin. Christensen and coworkers12 isolated crystalline tryptophane and leucine from a hydrolysate. They found no evidence for a fatty acid component and established that phenylalanine, proline and hydroxyproline were absent from a hydrolysate. These workers isolated alanine diox-pyridate from a hydrolysate and also established that gramicidin contained a compound with vicinal hydroxy and amino groups. They speculated that this compound might be serine or isoserine and proposed that gramicidin contains two tryptophane, 2 leucine, 2 or 3 alanine and 1 hydroxyamino residues or a multiple of this composition. 

The pyrrolidine ring is part of numerous natural products, and we have restricted the field to those alkaloids that contain an isolated pyrrolidine ring. We have thus excluded the so-called Sceletium (mesembrine) and Dendrobium (den-drobine) alkaloids, which have also been reviewed (3-5). The pyrrolidine ring is frequently encountered in proline residues of cyclopeptide alkaloids these have been reviewed already (7) and will not be discussed here. 

In another legume, Afzelia bella Harms (Caesalpinoidene), the same authors have isolated the new rrfree amino acids. The structure of the diacid 54 is based on mass, H, and l3C-NMR spectroscopy (95) the proposed absolute configuration of 54 was also demonstrated by X-ray diffraction (96). Compound 54 is probably identical with the diacid independently isolated from the red alga Chondria coerulescens (Crouan) Falk. (Rhodomelaceae) (97). 

Although no experiment has yet been reported to support the idea, it seems clear that a majority of the pyrrolidine alkaloids arise from the ornithine, pu-trescine, and proline pool. This could be the case for ficine (61) and isoficine (62), vochysine (63), and phyllospadine (64) but also of the Darlingia alkaloids, which share common features with hygrine this assertion probably also holds for the ruspolinone (25) and odorine-roxburghlin (59) families. Peripentadenine, isolated from a plant of the family Elaeocarpaceae, bears resemblance to other alkaloids of the elaeocarpus type such as isoelaeocarpicine (124) (161). It cannot be excluded, however, that spermidine may be a biosynthetic intermediate instead of putrescine. The question of the origin of ant alkaloid substances remains so far without an obvious answer. 

Plaquet et al. (PI) found in the urine of rachitic children peptides consisting of proline, hydroxyproline, and glycine, which they believed to be the products of collagen degradation. Two similar peptides containing considerable amounts of proline and hydroxyproline were isolated from the urine of a patient with rheumatoid arthritis by Mechanic et al. (Ml). One of these peptides consisted of three proline, two hydroxyproline, and nine glutamic acid residues, the second one consisted of four proline, four hydroxyproline, and one glutamic acid residues. The N-terminal amino acid in the first peptide was demonstrated to be hydroxyproline. 

By means of a procedure described above, Hanson and Fittkau (HI) isolated seventeen different peptides from normal urine. One of them, not belonging to the main peptide fraction, consisted of glutamic acid, and phenylalanine with alanine as the third not definitely established component. The remaining peptides contained five to ten different amino acid residues and some unidentified ninhydrin-positive constituents. Four amino acids, i.e., glutamic acid, aspartic acid, glycine, and alanine, were found in the majority of the peptides analyzed. Twelve peptides contained lysine and eight valine. Less frequently encountered were serine, threonine, tyrosine, leucine, phenylalanine, proline, hydroxyproline, and a-aminobutyric acid (found only in two cases). The amino acid composi-... 

A cytosolic binding protein for CsA was first isolated in 1984 and named cyclophilin, later cyclophilin A (CyPA), in reference to its high affinity for CsA (18). CyPA is a basic, abundant protein with a mass of 18 kDa, and it is found in a variety of tissues. The first clue to its function came in 1989 when two independent groups isolated the enzyme that catalyzes pepti-dyl proline isomerization/peptidylprolyl cis-trans isomerase (EC 5.2.1.8 PPIase), in protein chains and (re)discovered CyPA (19, 20). CyPA is a potent PPIase, and its enzymatic activity is strongly inhibited by CsA. 

Nakajima et al. (128) found that a number of diamines functioned as moderately effective ligands for Cu(II) in the catalytic aerobic oxidation of 2-naphthols. A series of proline derivatives were evaluated with the aniline ligand 187 providing optimal selectivities. Unfortunately, 2-naphthol affords only racemic binaphthol. With an isolated catalyst, formulated as 187 Cu(OH)Cl in analogy to the known TMEDA Cu(OH)Cl (TMEDA = A,A,A,A-tetramethylethylenediamine), oxidative... 

Isolation of individual amino acids started about 1820 by 1904 all of the naturally occurring amino acids in proteins had been isolated except methionine (Mueller, 1922) and threonine (Rose, 1937). One of the earliest methods for the separation of amino acids was through the differential volatility of their methyl or ethyl esters (Emil Fischer, 1901). This approach led to the discovery of valine, proline, and hydroxyproline. [In the 1970s Fischer s method was modified for microanalysis of proteins, separating the amino acid esters by gas phase chromatography. Separation is now usually performed by hplc (high pressure liquid chromatography).]... 

From the fore gut of Laccophilus minutus, a Bacillus pumilus strain was isolated which produced maculosin, the diketopiperazine formed from proline and tyrosine [103] 24, phenyl malonate 25, N-acetylphenylalanine 26, N-acetyl-tryptophane 27 and 3,4-dihydroxybenzoic acid [ 103]. Maculosin which has also been isolated from several microorganisms and sponges shows phytotoxic and cytotoxic properties [103], 3,4-dihydroxybenzoic acid shows antioxidant properties and was already found in pygidial defensive glands of several dytis-cid beetles. 

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