Crystallography

Bài giảng Tinh thể - Khoáng vật: Chương 4, cung cấp cho học viên những nội dung về: hình dạng tinh thể; hình đơn; hình ghép; cách suy đoán 47 hình đơn; các hình đơn của các tinh hệ;... Mời các bạn cùng tham khảo chi tiết nội dung bài giảng!

17p hanlamcoman 26-11-2022 12 3   Download

The plant enzyme phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) shows homology to histidine ammonia-lyase (HAL) whose structure has been solved by X-ray crystallography. Based on amino-acid sequence alignment of the two enzymes, mutagenesis was performed on amino-acid residues that were identical or similar to the active site residues in HAL to gain insight into the importance of this residues in PAL for substrate binding or catalysis. We mutated the following amino-acid residues: S203, R354, Y110, Y351, N260, Q348, F400, Q488 and L138....

11p system191 01-06-2013 65 4   Download

Venoms from crotalid and viperid snakes contain several peptide inhibitors which regulate the proteolytic activities of their snake-venom metalloproteinases (SVMPs) in a reversible manner under physiological conditions. In this report, we describe the high-resolution crystal structures of a SVMP, TM-3, from Taiwan habu (Trimeresurus mucrosquamatus) cocrystallized with the endogenous inhibitors pyroGlu-Asn-Trp (pENW), pyroGlu-Gln-Trp (pEQW) or pyroGlu-Lys-Trp (pEKW).

10p system191 01-06-2013 30 5   Download

Institute for Organic Chemistry, University of Karlsruhe, Germany; 2Institute for Organic Chemistry, Budapest University of Technology and Economics, Hungary Elucidation of the 3D structure of histidine ammonia-lyase (HAL, EC 4.3.1.3) from Pseudomonas putida by X-ray crystallography revealed that the electrophilic prosthetic group at the active site is 3,5-dihydro-5-methylidene-4H-i´ midazol-4-one (MIO) [Schwede, T.F., Retey, J., Schulz, G.E. (1999) Biochemistry, 38, 5355 –5361].

9p system191 01-06-2013 50 3   Download

Conservedphenylalanine 35 is one of the hydrophobic patch residues on the surface of cytochromeb5 (cytb5). This patch is partially exposed on the surface of cyt b5while its buried face is in direct van der Waals’contact with heme b. Resi-dues Phe35 and Phe/Tyr74 also form an aromatic channel with His39, which is one of the axial ligands of heme b. By site-directedmutagenesiswehaveproduced threemutantsof cytb5:Phe35fiTyr, Phe35fiLeu, and Phe35fiHis.

10p research12 23-04-2013 38 3   Download

X-ray crystallography of the nonheme manganese catalase fromLactobacillus plantarum(LPC) [Barynin, V.V., Whit-taker, M.M., Antonyuk, S.V., Lamzin, V.S., Harrison, P.M., Artymiuk, P.J. & Whittaker, J.W. (2001)Structure9, 725–738] has revealed the structure of the dimanganese redox cluster together with its protein environment. The oxidized [Mn(III)Mn(III)] cluster is bridged by two solvent molecules (oxo and hydroxo, respectively) together with a l1,3bridging glutamate carboxylate and is embedded in a web of hydrogen bonds involving an outer sphere tyrosine residue (Tyr42). ...

15p tumor12 20-04-2013 28 6   Download

NMR spectroscopy and X-ray crystallography have provi-ded important insight into structural features of phenyl-alanine hydroxylase (PAH) and tyrosine hydroxylase (TH). Nevertheless, significant problems such as the substrate specificity of PAHand the different susceptibility of TH to feedback inhibition by L-3,4-dihydroxyphenylalanine (L-DOPA) compared with dopamine (DA) remain unre-solved.

11p tumor12 20-04-2013 51 3   Download

To investigate the structural function of the C-terminal amide group of endomorphin-2 (EM2, H-Tyr-Pro-Phe-Phe-NH2), an endogenous l-opioid receptor ligand, the solution conformations of EM2 and its C-terminal free acid (EM2OH, H-Tyr-Pro-Phe-Phe-OH) in TFE (trifluoroethanol), water (pH 2.7 and 5.2), and aqueous DPC (dodecylphosphocholine) micelles (pH 3.5 and 5.2) were investigated by the combination of 2D 1 H-NMR meas-urement and molecular modelling calculation.

19p fptmusic 12-04-2013 32 4   Download

The structure of CLIC4, a member of the CLIC family of putative intracel-lular chloride ion channel proteins, has been determined at 1.8 A ˚ resolution by X-ray crystallography. The protein is monomeric and it is structurally similar to CLIC1, belonging to the GST fold class. Differences between the structures of CLIC1 and CLIC4 are localized to helix 2 in the glutaredoxin-like N-terminal domain, which has previously been shown to undergo a dra-matic structural change in CLIC1 upon oxidation.

12p fptmusic 12-04-2013 35 3   Download

The structure of cytochromec-550 from the nonphotosynthetic bacteria Paraccocus versutushas been solved by X-ray crystallography to 1.90 A˚ resolution, and reveals a high structural homology to other bacterial cyto-chromesc2. The effect of replacing the axial heme-iron methionine ligand with a lysine residue on protein structure and unfolding has been assessed using the M100K variant.

15p awards 06-04-2013 39 3   Download

Noncovalent binding of thioxylo-oligosaccharide inhibitors, methyl 4-thio-a-xylobioside (S-Xyl2-Me), methyl 4,4 II -dithio-a-xylotrioside (S-Xyl3-Me), methyl 4,4 II ,4 III -trithio-a-xylotetroside (S-Xyl4-Me), and methyl 4,4 II , 4 III ,4 IV -tetrathio-a-xylopentoside (S-Xyl5-Me), to three family 11 endo-1,4-b-xylanases from Trichoderma reesei(TRX I and TRX II) and Chaetomium thermophilum (CTX) was characterized using electrospray ionization Fourier transform ion cyclotron resonance (FT-ICR) MS and X-ray crys-tallography. ...

17p awards 06-04-2013 38 3   Download

The solution structure ofNereis diversicolorsarcoplasmic calcium-binding protein (NSCP) in the calcium-bound form was determined by NMR spec-troscopy, distance geometry and simulated annealing. Based on 1859 NOE restraints and 262 angular restraints, 17 structures were generated with a rmsd of 0.87 A ˚ from the mean structure. The solution structure, which is highly similar to the structure obtained by X-ray crystallography, includes two open EF-hand domains, which are in close contact through their hydrophobic surfaces....

15p awards 06-04-2013 51 3   Download

Antifreeze proteins (AFPs) designate a class of proteins that are able tobind toand inhibit the growthofmacromolecular ice. These proteins have been characterized froma variety of organisms. Recently, the structures ofAFPs fromthe spruce budworm (Choristoneura fumiferana) and the yellow meal-worm (Tenebrio molitor) have been determined by NMR and X-ray crystallography. Despite nonhomologous sequences, both proteins were shown to consist ofb-helices.

12p awards 05-04-2013 43 5   Download

Analysis of the molecular properties of proteins extracted from organisms living under extreme conditions often highlights peculiar features. We investigated by UV-visible spectroscopy and X-ray crystallography the oxidation pro-cess, promoted by air or ferricyanide, of five hemoglobins extracted from Antarctic fishes (Notothenioidei).

9p dell39 03-04-2013 30 4   Download

The poorly known mechanism of inhibition of cholinesterases by inorganic mercury (HgCl2) has been studied with a view to using these enzymes as biomarkers or as biological components of biosensors to survey polluted areas. The inhibition of a variety of cholinesterases by HgCl2 was investi-gated by kinetic studies, X-ray crystallography, and dynamic light scatter-ing.

13p galaxyss3 21-03-2013 50 4   Download

The direct conversion of plant cell wall polysaccharides into soluble sugars is one of the most important reactions on earth, and is performed by cer-tain microorganisms such as Clostridium thermocellum(Ct). These organ-isms produce extracellular multi-subunit complexes (i.e. cellulosomes) comprising a consortium of enzymes, which contain noncatalytic carbohy-drate-binding modules (CBM) that increase the activity of the catalytic module.

12p media19 06-03-2013 46 4   Download

The number of macromolecular structures deposited in the Protein Data Bank now exceeds 45 000, with the vast majority determined using crystal-lographic methods. Thousands of studies describing such structures have been published in the scientific literature, and 14 Nobel prizes in chemistry or medicine have been awarded to protein crystallographers.

21p media19 05-03-2013 39 3   Download

Enolase is a validated drug target inTrypanosoma brucei. To better charac-terize its properties and guide drug design efforts, we have determined six new crystal structures of the enzyme, in various ligation states and confor-mations, and have carried out complementary molecular dynamics simula-tions.

13p media19 04-03-2013 55 3   Download

Exploring enzymatic mechanisms at a molecular level is one of the major challenges in modern biophysics. Based on enzyme structure data, as obtained by X-ray crystallography or NMR spectroscopy, one can suggest how substrates and products bind for catalysis.

14p vinaphone15 25-02-2013 42 2   Download

In ruminants, some leaf-eating animals, and some insects, defensive lyso-zymes have been adapted to become digestive enzymes, in order to digest bacteria in the stomach. Digestive lysozyme has been reported to be resis-tant to protease and to have optimal activity at acidic pH. The structural basis of the adaptation providing persistence of lytic activity under severe gastric conditions remains unclear.

9p viettel02 22-02-2013 38 3   Download