Chronic kidney disease (CKD) is increasingly recognized as a major health problem worldwide. Objectives: (1) To evaluate the malondialdehyde concentration and kynurenine and tryptophan ratio for differences between CKD patients and healthy controls. (2) To analyze the relationship and correlation between these biomarker indexes and some risk factors of CKD.

Luận văn này tổng hợp được phức rắn của Ln3+ với L – tyrosin, L - tryptophan. (Ln3+ : Ho3+, Er3+). Bước ñầu thăm dò ảnh hưởng của các phức [Ho(tryp)3]Cl3.3H2O, [Er(tryp)3]Cl3.3H2O ñến sự nảy mầm, phát triển mầm và hàm lượng protein, proteaza , α- amilaza của mầm hạt ngô. Mời các bạn cùng tham khảo!

Mục đích của Luận văn là nghiên cứu phức chất của một số nguyên tố đất hiếm với aminoaxit và thăm dò hoạt tính sinh học của chúng tạo cơ sở khoa học cho việc sử dụng, khai thác tài nguyên thiên nhiên của Việt Nam là có ý nghĩa khoa học và thực tiễn. Mời các bạn cùng tham khảo!

Tiêu chuẩn Quốc gia TCVN 5283:2007 mô tả phương pháp xác định hàm lượng tryptophan tự do và tổng số trong thức ăn chăn nuôi (ví dụ: thức ăn hoàn chỉnh và thức ăn bổ sung, nguyên liệu thô, nguyên liệu trong hỗn hợp, sản phẩm premix, thức ăn đậm đặc…). Không phân biệt giữa dạng D- và L-.

Laboratory for Lipoprotein Chemistry and 4Flanders Interuniversity Institute for Biotechnology, Department of Medical Protein Research, Faculty of Medicine, Department of Biochemistry, Ghent University, Belgium; 2Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Belgium; 3Ecole Normale Supe´rieure, Paris, France Penetratin is a 16-amino-acid peptide, derived from the homeodomain of antennapedia, a Drosophila transcription factor, which can be used as a vector for the intracellular delivery of peptides or oligonucleotides....

We previously demonstrated inmast cell lines RBL2H3 and FMA3 that tryptophan hydroxylase (TPH) undergoes very fast turnover driven by 26S-proteasomes [Kojima, M., Oguro, K., Sawabe, K., Iida, Y., Ikeda, R., Yamashita, A., Nakanishi, N. & Hasegawa, H. (2000)J.Biochem (Tokyo) 2000,127, 121–127]. In the present study, we have examined an involvement of TPH phosphorylation in the rapid turn-over, using non-neural TPH.

Plasmodium falciparumtriosephosphate isomerase (PfTIM) contains two tryptophan residues, W11 and W168. One is positioned in the interior of the protein, and the other is located on the active-site loop 6. Two single-tryptophan mutants, W11F and W168F, were constructed to evaluate the contributions of each chromophore to the fluorescence of the wild-type (wt) protein and to probe the utility of the residues as spectroscopic reporters.

One-electron oxidation of six different c-type lysozymes from hen egg white, turkey egg white, human milk, horse milk, camel stomach and tortoise was studied by gamma-and pulse-radiolysis.In the first step, one tryptophan side chain is oxidized to indolyl free radical, which is produced quantitatively.As shown already, the indolyl radical subse-quently oxidizes a tyrosine side chain to the phenoxy radical in an intramolecular reaction.However this reaction is not total and its stoichiometry depends on the protein.Rate constants also vary between proteins, from 120Æs )1 to 1000Æs )1 at pH 7.0 and room temperature [extremes are hen and turkey egg white (120Æs )1 ) and human milk (1000Æs )1 )]....

We examined the microenvironment of the single trypto-phan and the tyrosine residues of PsbQ, one of the three main extrinsic proteins of green algal and higher plant photosystem II. On the basis of this information and the previous data on secondary structure [Balsera, M., Arel-lano, J.B., Gutie´rrez, J.R., Heredia, P., Revuelta, J.L. & De Las Rivas, J. (2003)Biochemistry42, 1000–1007], we screened structural models derived by combining various threading approaches.

Amathematicalmodel hasbeendevelopedtostudy theeffect of external tryptophan on the trp operon. The model accounts for the effect of feedback repression by tryptophan through the Hill equation. We demonstrate that the trp operonmaintains an intracellular steady-state concentration in a fivefold range irrespective of extracellular conditions. Dynamic behavior of thetrp operon corresponding to varying levels of extracellular tryptophan illustrates the adaptive nature of regulation.

The enzymatic nitration of tryptophan derivatives by oxi-dation of nitrite has been studied using lactoperoxidase and horseradish peroxidase, and compared with the chemical nitration produced by nitrogen dioxide and peroxynitrite. HPLC, mass spectra and NMR analysis of the mixture of products clearly show that nitrationoccurs at position 4-, 6-, 7-, andN 1 of the indole ring, and nitrosation at positionN 1 . Kinetic studies performed on peroxidase/NO2 – /H2O2 sys-tems showed substrate saturation behavior with all the tryptophan derivatives employed. ...

The structure of the tryptophan synthaseb2 subunit (Pfb2 ) from the hyperthermophile,Pyrococcus furiosus,was deter-mined by X-ray crystallographic analysis at 2.2 A˚ resolu-tion, and its stability was examined byDSC. This is the first report of the X-ray structure of the tryptophan synthaseb2 subunit alone, although the structure of the tryptophan synthase a2b2 complex fromSalmonella typhimuriumhas already been reported. The structure ofPfb2was essentially similartothatoftheb2 subunit (Stb2)inthea2b2complex from S. typhimurium....

The flavoenzyme d-amino acid oxidase from Rhodotorula gracilisis a homodimeric protein whose dimeric state has been proposed to occur as a result of (a) the electrostatic interactions between positively charged resi-dues of thebF5–bF6 loop of one monomer and negatively charged residues belonging to thea-helices I3¢ and I3¢¢ of the other monomer, and (b) the interaction of residues (e.g. Trp243) belonging to the two monomers at the mixed interface region.

The heterologous expression of tryptophan trytophylquinone (TTQ)-dependent aromatic amine dehydrogenase (AADH) has been achieved in Paracoccus denitrificans. The aauBEDAgenes andorf-2from the aromatic amine utilization (aau) gene cluster of Alcaligenes faecaliswere placed under the regulatory control of themauFpromoter fromP. denitrificans and introduced intoP. denitrificansusing a broad-host-range vector.

2-Amino 3-carboxymuconate 6-semialdehyde decarboxylase (ACMSD, EC 4.1.1.45) plays a key role in tryptophan catabolism. By diverting 2-amino 3-carboxymuconate semialdehyde from quinolinate production, the enzyme regulates NAD biosynthesis from the amino acid, directly affecting quinoli-nate and picolinate formation.

Antichymotrypsin, a member of the serpin superfamily, has been shown to form inactive polymers in vivo, leading to chronic obstructive pulmonary disease. At present, however, the molecular determinants underlying the polymerization transition are unclear.

Ascorbate peroxidase (APX) isoforms localized in the stroma and thyla-koid membrane of chloroplasts play a central role in scavenging reactive oxygen species generated by photosystems. These enzymes are inactivated within minutes by H2O2 when the reducing substrate, ascorbate, is deple-ted.

Pig kidney fructose-1,6-bisphosphatase is a homotetrameric enzyme which does not contain tryptophan. In a previous report the guanidine hydrochlo-ride-induced unfolding of the enzyme has been described as a multistate process [Reyes, A. M., Ludwig, H. C., Yan˜ez, A. J., Rodriguez, P. H and Slebe, J. C.

The hexameric glutamate dehydrogenase ofClostridium symbiosumhas pre-viously been shown to undergo a pH-dependent inactivating conformational change that perturbs the environment of one or more Trp residues and is reversed by glutamate in a highly cooperative fashion with a Hill coefficient of almost 6.

To understand the basis for the lower activity of the tryptophan synthaseb2 subunit in comparison to thea2b2 complex, we determined the crystal struc-tures of apo-b2 and holo-b2 from Escherichia coliat 3.0 and 2.9 A˚ resolu-tions, respectively. To our knowledge, this is the first report of both b2 subunit structures with and without pyridoxal-5¢-phosphate.