3-Hydroxy proline

In supported liquid membranes, a chiral liquid is immobilized in the pores of a membrane by capillary and interfacial tension forces. The immobilized film can keep apart two miscible liquids that do not wet the porous membrane. Vaidya et al. [10] reported the effects of membrane type (structure and wettability) on the stability of solvents in the pores of the membrane. Examples of chiral separation by a supported liquid membrane are extraction of chiral ammonium cations by a supported (micro-porous polypropylene film) membrane [11] and the enantiomeric separation of propranolol (2) and bupranolol (3) by a nitrate membrane with a A/ -hexadecyl-L-hydroxy proline carrier [12]. 

In more recent times chemically defined basal media have been elaborated, on which the growth of various lactic acid bacteria is luxuriant and acid production is near-optimal. The proportions of the nutrients in the basal media have been determined which induce maximum sensitivity of the organisms for the test substance and minimize the stimulatory or inhibitory action of other nutrilites introduced with the test sample. Assay conditions have been provided which permit the attainment of satisfactory precision and accuracy in the determination of amino acids. Experimental techniques have been provided which facilitate the microbiological determination of amino acids. On the whole, microbiological procedures now available for the determination of all the amino acids except hydroxy-proline are convenient, reasonably accurate, and applicable to the assay of purified proteins, food, blood, urine, plant products, and other types of biological materials. On the other hand, it is improbable that any microbiological procedure approaches perfection and it is to be expected that old methods will be improved and new ones proposed by the many investigators interested in this problem. 

Yu, H., and Langer, R., Pseudopoly(amino acids) A study of the synthesis and characterization of poly(acyl-hydroxy-proline esters). Macromolecules. 22, 3250-3255, 1989. 

On the other hand, resonance assignments for CP of threonine and serine, and C and Cy of hydroxy proline, were difficult to make, because of their proximity to carbohydrate carbon resonances. In most cases then, the resonances were assigned on the basis of the effects of pH on the chemical shifts of those resonances. It was shown that the chemical shifts for the carbohydrate carbon resonances were virtually unaffected (AS 0.4 p.p.m.) when going from the cationic state (pH 2) to the anionic state (pH 11) of the amino acid residues. The chemical shifts of C and CP of the amino acid residues, however, shifted considerably (up to 3.1 and 6.6 p.p.m. for C" and CP, respectively see Table VI). 

Soybean stem Hydroxy-proline and glycine-rich protein and mRNA analysis Vamer and Ye (25)... 

H Kuroda, S Kubo, N Chino, T Kimura, S Sakakibara. Unexpected racemization of proline and hydroxy-proline phenacyl ester during coupling reactions of Boc-amino acids. Int J Pept Prot Res 40, 114, 1992. 

In connection with the enantioselective alkylation of Pro or 4-hydroxy-proline, the azabicyclo[3.3.0]octane system 81 was obtained after reaction with pivaldehyde (81HCA2704 85HCA155). In a more complex transformation A-protected L-Pro was transformed into the same bicyclic system (Scheme 49) (81JA1851 84JA4192). The product was prepared as a model substance in the total synthesis of pumiliotoxin. A related compound 82 was prepared from 5-(hydroxymethyl)-2-pyrrolidinone (prepared from L-pyroglutamic acid) by an acid-catalyzed condensation with benzaldehyde (86JOC3140). 

In the first syntheses of CCK-related peptides that lack serine, threonine, or hydroxy-proline residues, sulfation of tyrosine residues was accomplished by treatment of the fully deprotected peptides with sulfuric acid. Under optimized conditions good separation between sulfated, sulfonated, and unreacted species (Scheme 2) was achieved using ion-ex-change chromatography. 3435 Sulfonation of the indole group, as observed in model studies/731 is apparently not a dominant side reaction. 

Substances that guarantee the chemical and mechanical stability of the cornea are mostly collagen type I and X that are mainly made of proline and hydroxy-proline. Other substances that are present in a considerable amount are proteins (pK between 5.3 and 9), vitamin C (pK = 4.2), bicarbonate, glutathione, and lactate. (For more details about pK refer to Chap. 3, Sect. 3.2.4.1)... 

Hydroxyproline and hydroxylysine Collagen contains hydroxy proline (hyp) and hydroxylysine (hyl), which are not present in most other proteins. These residues result from the hydroxylation of some of the proline and lysine residues after their incorporation into polypeptide chains (Figure 4.6). The hydroxylation is, thus, an example of posttranslational modification (see p. 440). Hydroxy proline is important in stabilizing the triple-helical structure of colla gen because it maximizes interchain hydrogen bond formation. 

A. One third of the amino acids of collagen is hydroxy-proline. 

The 216-residue hen egg yolk storage protein phosvitin contains 123 serine residues, most of which have been phosphorylated (Eq. 2-16).295 A basic protein of the myelin sheath of neurons contains as many as 6 specific residues of citrulline (Eq. 2-19).296 An adhesive protein from the foot of a marine mollusk contains -80 repeated sequences containing hydroxy-proline 2,3-dihydroxyproline and 3,4-dihydroxyphenylalanine (Dopa) 297/298... 

An alternative workup procedure takes advantage of the solubility of the lactone in MeOH. Upon completion of the reaction, the residual oil was dissolved in EtOAc and washed with 5% aq citric acid (50 mL), H20 (2 x 50 mL), 5% NaHC03 (50 mL), and H20 (2 x 50 mL). The organic phase was dried and concentrated, and the oil triturated with MeOH to afford the crystalline product yield 4.9 g (55%). The latter workup procedure, while very simple and economic, cannot be applied to other N-protected lactones, e.g. to the TV-Boc-4-hydroxy proline lactone, where careful flash chromatography was required for separation of other polar byproducts including Ph3PO. 

Analysis shows the presence of amino acids from 0.2% tyrosine to 30.5% glycine. The live most common amino acids are glycine, 26.4-30.5% proline. 14.8— 189b hydroxy proline. 13.3-14.5% glutamic acid, 11.1 - 11,7% and alanine. 8.6- 11.3%. The remaining amino acids in decreasing order are arginine, aspartic acid, lysine, serine, leucine, valine, phenylalanine, threonine, isolcucine, hydroxylysine, histidine, methionine, and tyrosine. 

Averyhart-Fullard, V., Datta, K. Marcus, A. (1988). A hydroxy-proline-rich protein in the soybean cell wall. Proceedings of the National Academy of Sciences (USA) 85, 1082-5. 

In 2001 Uozomi et al. reported that the (3-methyl)tetrahydrophthalic anhydride rac-21 undergoes parallel kinetic resolution when treated with methanol in the presence of the hydroxy proline derivative 13e (Scheme 13.10) [17]. The resulting esters 22 and 23 were formed with up to 80% ee, albeit at chemical yields of 12% and 29%, respectively. 

In model experiments L-proline, hydroxy-proline, cysteine and methionine were heated with monosaccharides for 1 - 1.5 h at 150 C. 

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