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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.22, #2)

Homocysteine and cysteine – albumin binding in homocystinuria: assessment of cysteine status and implications for glutathione synthesis? by I. P. Hargreaves; P. J. Lee; A. Briddon (pp. 109-118).

Measurement of plasma total cysteine rather than free dimeric cystine gives a better indication of cysteine status in homocystinuric patients. This is the result of displacement of cysteine from albumin by homocysteine and is related to the plasma homocysteine concentration. In control subjects the free/bound cyst(e)ine ratio was independent of albumin and total cysteine concentrations. In homocystinuric (HCU) patients both free and total cyst(e)ine values differed significantly from control values (P < 0.001) but whilst free cystine considerably overlapped control values the total cysteine concentrations were almost invariably lower. The possible consequences of this on glutathione synthesis was explored by assay of plasma total glutathione but no evidence for glutathione deficiency was found. Measurement of total cysteine, rather than free cystine, provides a better indication of cysteine status in HCU.

Keywords: Keywords: Aminothiols; Homocysteine; Cysteine; Homocystinuria; Glutathione; Albumin

Age-related salivary polyamine increase in adolescents wearing orthodontic Ni-Ti archwires by M. Venza; M. Visalli; P. Ruggeri; D. Cicciù; D. Teti (pp. 119-130).

Until now information about the influence of puberty on gingival tissue responses to Ni-Ti alloy haven't been available. Since our previous researches have demonstrated that Ni-Ti appliances have an influence on hyperplastic gingivopathy and data has pointed out a possible hormonal influence on the susceptibility of gingival tissue to mechanical stress, we have attempted to study the relationship between fertility hormones and the periodontal response to Ni-Ti appliances. Three groups, ranging from 6 to 17 years old, were tested for salivary polyamine concentrations and for fertility hormone levels 12 months after Ni-Ti application. Results obtained from Pearson's correlation coefficient between polyamine and sexual hormone concentrations, as well as gingival and plaque indexes, suggest that the adolescent gingival tissue undergoes an hyperplastic process after long-term use of Ni-Ti appliances in relation to the puberty age-restricted peak of fertility hormones.

Keywords: Keywords: Amino acids; Hyperplastic gingivitis; Orthodontic wires; Polyamines; Saliva

The specific anti-cancer activity of green tea (−)-epigallocatechin-3-gallate (EGCG) by Y.-C. Wang; U. Bachrach (pp. 131-143).

The effect of the green tea polyphenol-(−)epigallocatechin-3-gallate (EGCG) was tested in cultures of normal and transformed NIH-pATMras fibroblasts. In this system transformation can be induced at will by the addition of dexamethasone, which induces the expression of H-ras by activating the mammary tumor virus long terminal repeat (MMTV-LTR) promoter. This facilitates a reliable comparison of the susceptibility of normal and transformed cells to EGCG. It has been shown that EGCG inhibited the growth of transformed but not of the normal fibroblasts. In an attempt to elucidate the mode of the preferential inhibitory activity of EGCG, its effect on growth promoting factors has been examined. The level of ornithine decarboxylase (ODC, EC 4.1.1.17), which is a signal for cellular proliferation, was reduced by EGCG in the transformed but not in the normal cells. EGCG also showed strong inhibition of tyrosine kinase and mitogen-activated protein kinase (MAPK) activities, without affecting the kinases in the normal cells. Similarly, EGCG also preferentially decreased the levels of the oncogenes Ras and Jun in transformed cell. EGCG preferentially induced apoptosis in the transformed fibroblasts. In vitro chemosensitivity tests demonstrated that EGCG inhibited the proliferation of leukemic cells. These findings suggest that EGCG has a therapeutic potential in the combat against cancer.

Keywords: Keywords: Amino acids; (; )-Epigallocatechin-3-gallate (EGCG); Ornithine decarboxylase (ODC); Tyrosine kinase; Mitogen-activated protein kinase (MAPK); Oncogene; Apoptosis

Sulphoacetaldehyde as a product of taurine chloramine peroxidation at site of inflammation by S. Olszowski; E. Olszowska; D. Kusior; E. Szneler (pp. 145-153).

It has been reported, that sulphoacetalhehyde is formed in the fagocytozing PMNs and its production is taurine monochloramine mediated. Since H₂O₂ and secreted MPO are present in the medium the non- and enzymatic peroxidation of taurine of its mono- and dichloramines were examined within the pH range 5.3–7.4. The formation of sulphoacetaldehyde was observed in nonenzymatic hydrolysis of taurine N,N-dichloramine (pH 5.3) as well as for monochloramine at pH 7.4. It was found also that its formation was accelerated in the presence of H₂O₂, in the MPO/H₂O₂ and in the full system containing Cl⁻. Additionally it was shown that also horseradish peroxidase (HRP) could catalyze sulphoacetaldehyde production. The sulphoacetaldehyde formation in the examined systems was confirmed with the use of ¹HNMR spectra of separated 2,4-dinitrophenylhydrazone derivative. Our results suggest that both non- and ezymatic processes could contribute to the sulphoacetaldehyde formation at site of inflammation.

Keywords: Keywords: Amino acids; Sulphoacetaldehyde; Taurine dichloramine; Myeloperoxidase; Horseradish peroxidase

The ability of cystamine to bind DNA by P. Allegra; E. Amodeo; S. Colombatto; S. P. Solinas (pp. 155-166).

The DNA-binding properties of cystamine compared with natural occurring polyamines have been studied in vitro by means of ethidium bromide displacement assays, studies of DNA thermal stability and analyses of DNA-B/DNA-A transition. While the first two methods did not put in evidence any peculiar property in the binding capability of cystamine, CD studies showed the interesting ability of cystamine to shift the equilibrium B/A-DNA towards the B-form. In the same experimental conditions spermine and spermidine induced the A form of DNA, instead putrescine and cadaverine did not show any particular activity. The ability of cystamine to bind DNA, as shown also by its DNA radioprotective capability, might be important in chromatin condensation and stabilization, and might be a cause of the antiviral activity observed by some authors.

Keywords: Keywords: Amino acids; Cystamine; DNA interaction; Cysteine metabolism; Sulfur containing diamine; Polyamine

Aromatic amino acid biosynthesis and production of related compounds from p-hydroxyphenylpyruvic acid by rumen bacteria, protozoa and their mixture by R. I. Khan; R. Onodera; M. R. Amin; N. Mohammed (pp. 167-177).

Aromatic amino acid biosynthesis and production of related compounds from p-hydroxyphenylpyruvic acid (HPY) by mixed rumen bacteria (B), protozoa (P), and their mixture (BP) in an in vitro system were quantitatively investigated. Microbial suspensions prepared from mature, fistulated goats fed Lucerne (Medicago sativa) cubes and a concentrate mixture were anaerobically incubated at 39°C for 12 h. Tyrosine (Tyr), phenylalanine (Phe), tryptophan (Trp) and other related compounds in both supernatants and hydrolyzates of all incubations were analyzed by HPLC. Large amounts of Tyr (27.0, 47.0 and 50.8% of disappeared HPY in B, P and BP, respectively) were produced from 1 mM HPY during a 12-h incubation period. The formation of Tyr in P was 1.8 and 1.6 times higher than those in B and BP, respectively. Appreciable amounts of Phe (3–12% of the disappeared HPY) and Trp (2–10% of the disappeared HPY) were also produced from HPY in B, P, and BP. Phe synthesis in B and P was almost similar but Trp synthesis in B was 1.8 times higher than that in P. The biosynthesis of both Phe and Trp from HPY in BP was higher than those in B plus P. A large amount of p-hydroxyphenylacetic acid (about 45% of the disappeared HPY) was produced from HPY in B which was 1.9 times higher than that in P. p-Hydroxybenzoic acid produced from HPY in P was 1.6 times higher than that in B. Considerable amounts of phenylpropionic acid, phenyllactic acid, and phenylpyruvic acid (2–6% of the disappeared HPY) were produced only in B.

Keywords: Keywords: Aromatic amino acid; p-Hydroxyphenylpyruvic acid; Rumen bacteria; Rumen protozoa

Synthesis of (2S,4S)-4-phenylamino-5-oxoproline derivatives by I. A. Nizova; V. P. Krasnov; G. L. Levit; M. I. Kodess (pp. 179-186).

The paper describes the synthesis of (2S,4S)-4-(N-Ts)- and (2S,4S)-4-(N-Boc)-phenylamino-5-oxoprolines (pyroglutamic acid). These derivatives have been shown to be useful for synthesis of their amides and peptides in spite of steric hindrances caused by bulky groups adjacent to the reaction centre. Under the conditions applied no lactam ring opening and no loss of stereochemical integrity of any of the chiral centres were observed, which has been confirmed by NMR techniques.

Keywords: Keywords: Amino acids; Pyroglutamic acid; Amides; Peptides; Protecting groups; NMR spectroscopy

An investigation on skin wound healing in mice with a taurine-chitosan gel formulation by Z. Değim; N. Çelebi; H. Sayan; A. Babül; D. Erdoğan; G. Take (pp. 187-198).

The process of wound healing begins immediately following surface lesions or just after exposure to radiation, chemical agents or extreme temperatures.Taurine (2-aminoethane sulfonic acid), an amino acid containing sulfur, is found in almost all tissues in mammals, playing various important physio-logical roles in each organ. Taurine exhibits an antioxidant effect and is also known to have effects on cell proliferation, inflammation and collagenogenesis. Many antioxidants have been used to eliminate the negative effects of oxygen free radicals on wound healing.The objective of the present study was to examine the wound healing effect in mice of taurine-chitosan gel, which releases taurine slowly over a long time period. Fifty mM of taurine in 1.5% chitosan polymer (TAU-GEL) and 1.5% chitosan polymer (CHI-GEL) were applied to full thickness skin wounds of mice once a day for seven days. After seven days of treatment, lipid peroxide formation-malondialdehyde (MDA) and hydroxyproline (HPX) levels and the tensile strength of wound tissues were measured. All results were compared with those of the untreated control group (CONT). The structural alterations in the skin layers were also histologically investigated.It was found that locally administered TAU-GEL form significantly increased wound tensile strength by decreasing the MDA and increasing HPX levels. These results were supported by histological findings. All observations suggest that taurine gel may be effective in wound healing.

Keywords: Keywords: Amino acids; Chitosan; Gel; Hydroxyproline; Malondialdehyde; Taurine; Tensile strength; Wound healing

Caramelization of maltose solution in presence of alanine by H. H. M. Fadel; A. Farouk (pp. 199-213).

Two solutions of maltose in water were used to prepare caramels. Alanine as a catalyst was added to one of these solutions. The caramelization was conducted at 130°C for total time period 90 minutes. Convenient samples were taken of each caramel solution every 30 min and subjected to sensory analysis and isolation of volatile components. The odour and colour sensory tests were evaluated according to the international standard methods (ISO). The results showed that, the presence of alanine gave rise to a high significant (P < 0.01) decrease in acid attributes and remarkable increase in the sweet and caramel attributes, which are the most important caramel notes. On the other hand the increase in heating time in presence of alanine as a catalyst resulted in a high significant (P < 0.01) increase in the browning rate of caramel solution. The new technique Solid Phase Micro Extraction (SPME) was used for trapping the volatile components in the headspace of each caramel samples followed by thermal desorption and GC and GC – MS analysis. The 5-hydroxymethyl-2-furfural (HMF), the main characteristic caramel product, showed its highest value in sample containing alanine after heating for 60 minutes. The best sensory results of the sample contains alanine were confirmed by the presence of high concentrations of the most potent odorants of caramel besides to the formation of some volatile compounds have caramel like flavours such as 2-acetyl pyrrole, 2-furanones and 1-(2-furanyl)1,2-propandione.

Keywords: Keywords: Amino acids; Caramel; Maillard reaction; Maltose; Potent odorants; Sensory evaluation

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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.22, #2)