Hydroxyproline/proline

Ornithine, proline, hydroxyproline, pipecolic acid and sarcosine yield red zones, glycine greenish-brown and the other amino acids weakly brown ones [3]. The colors of the zones are different if an alcoholic solution of potassium carbonate is used for basification instead of dipping solution II. 

Removal of a-amino nitrogen by transamination (see Figure 28-3) is the first catabolic reaction of amino acids except in the case of proline, hydroxyproline, threonine, and lysine. The residual hydrocarbon skeleton is then degraded to amphibolic intermediates as outhned in Figure 30-1. 

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-... 

Amino acids and some small peptides are absorbed into the enterocytes in the jejnnnm. The transport of amino acids from the lumen into the ceU is an active process, coupled to the transport of Na ions down a concentration gradient. There are at least six carrier systems with different amino acid specificities neutral amino acids (i.e. those with no net charge, e.g. branched-chain amino acids) neutral plus basic amino acids imino acids (proline, hydroxyproline) and glycine basic amino acids (e.g. arginine and lysine) P-amino acids and taurine acidic amino acids (glutamic and aspartic acids). 

Amino acids are by definition low-molecular-weight mono- or dicarboxylic acids with one or more amino groups. A few imino acids (proline, hydroxyproline, pipe-colic acid) are also considered to belong to this group of biologically important substances. 

Orthophthalaldehyde (OPA) in combination with a thiol is the reagent of choice for derivatization, despite its inability to react with proline, hydroxyproline, and the sulfur-containing amino acids. Another drawback of the reagent is the instability of the reaction products, making an automated derivatization system coupled to an automated injector, and constant retention times an absolute necessity. Taking into account these considerations, the HPLC analysis will be of use to every biochemical genetics laboratory for biological fluids other than urine. The system has also a... 

Age does not have a major influence on amino acid levels, with exception of the neonatal period. Premature babies may have underdeveloped hepatic and renal function, leading to increased tyrosine and methionine in their plasma as well as enhanced urinary losses of cystine, lysine, glycine, proline, hydroxyproline, and cystathionine. Taurine levels are generally increased in the first days of life. 

The red pigment isolated in crystalline form from the reaction products of 1-methyl-3,4-benzoquinone and 4-hydroxyproline ethyl ester was identified as 4-(4 -hydroxy-2 -carbethoxy-l -pyrrolidyl)-5-methyl-l,2-benzoquinone (115).283 This highly colored compound should probably be formulated as a zwitterion (116). Similar pigments can be obtained by the interaction of o-benzoquinone with proline, hydroxyproline, pyrrolidine, and glycine. Suzuki has shown... 

Cofactor for hydroxylation reactions, for example In procollagen Proline -> hydroxyproline Lysine -> hydroxylysine —Ot.QrT Y i —. ft... 

Type IB sorbents are chiral ligand exchangers. Several columns are commercially available with either proline, hydroxyproline, or valine and Cu(II) bonded to silica [256]. The binding is via a 3-glycidoxpropyl spacer Cu(II) needs to be added to the mobile phase to minimize the loss of copper from the sorbent. Silica modified by L-( + )-tartaric acid has also been synthesized. These columns generally have poor efficiency and analytes are limited to bidentate solutes [256]. 

Polypeptides, however, are composed of amino acids with side chains that are longer and therefore the area of allowed conformations is reduced when an alanine (Figure 2.12), aspartic acid (Figure 2.13), or a proline (Figure 2.14) is added to the second peptide unit. Finally, the conformational map for a dipeptide of proline-hydroxyproline is dramatically reduced. Rings in the backbone of any polymer reduce the ability of the polymer backbone to adopt numerous conformations and thereby stiffen the structure. 

Methionine Cysteine/cystine Arginine Histidine Serine Glycine Threonine Proline/hydroxyproline Valine Tryptophan... 

Figure 20.19 Biosynthesis and degradation of proline, hydroxyproline and ornithine. Proline oxidase and S-pyrroIine-5-carboxylic acid dehydrogenase are both mitochondrial enzymes. A and B indicate defects in hyperprolinemia I and II, respectively.

Other Oxazolidine as well as Thiazolidine Derivatives for Branching Amino Acids. The cyclic derivative of alanine and other amino acids employed most frequently for a-allq lation is not (1) but rather the benzaldehyde acetal (5), either with a benzoyl or with a Cbz group on nitrogen. These compounds were used for the preparation of 2-methyl-2-aminobutanoic acid, a-methylphenylalanine, a-methyllysine, 2-methylaspartic acid, and 2-methylglutamic acid. Bicyclic compounds containing oxazolidinone rings such as (6) (from alanine, leucine, and phenylalanine) and (7) (from azetidinecaiboxylic acid, proline, " hydroxyproline, and cysteine ) have also been applied to the synthesis of branched amino acids. 

When a Boc amino acid is being coupled to a N-tenninal proline, hydroxyproline, or other secondary amino group, the Kaiser test is negative or gives an inconclusive brownish color. Such N-terminal residues give a good blue color with isatin.P ... 

The reagent is of value as a precipitant for primary and secondary amines, proline, hydroxyproline, and certain other amino acids. 

Absorption of proline, hydroxyproline, and glycine in renal tubule... 

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