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H Gouda

Publications and source records attributed to H Gouda.

12 recordsLinked to original sources
PubMed1999

Solution structure of alpha-conotoxin ImI determined by two-dimensional NMR spectroscopy.

The three-dimensional structure of alpha-conotoxin ImI, a potent antagonist targeting the neuronal alpha7 subtype of nicotinic acetylcholine receptor (nAChR), has been investigated by NMR spectroscopy. On the basis of 181 experimental constraints, a total of 25 converged structures were obtained. The average pairwise atomic root mean square difference is 0.40+/-0.11 A for the backbone atoms. The resulting structure indicates the presence of two successive type I beta-turns and a 310 helix for residues Cys2-Cys8 and Ala9-Arg11, respectively, and shows a significant structural similarity to that of alpha-conotoxin PnIA, which is also selective for the neuronal nAChR.

Conotoxins↗
PubMed1998

NMR study of the interaction between the B domain of staphylococcal protein A and the Fc portion of immunoglobulin G.

The solution structure of the B domain of staphylococcal protein A (FB) complexed with the Fc fragment of immunoglobulin G (IgG) is reported. A previous NMR analysis has shown that in solution FB is composed of a bundle of three alpha-helices, helix I, helix II, and helix III [Gouda, H., Torigoe, H., Saito, A., Sato, M., Arata, Y., and Shimada, I. (1992) Biochemistry 31, 9665-9672]. In contrast, the crystal structure of FB in the FB-Fc complex lacks helix III. Uniformly 15N- and 15N/13C-labeled FB were prepared, and the backbone 13C resonances were assigned. The spectral data obtained in the present study indicated that in solution all three helices including helix III are preserved in the FB-Fc complex. The mode of interaction of FB with the Fc fragment was discussed on the basis of the combined data of hydrogen-deuterium exchange experiments and 1H-15N correlation spectroscopy. It was concluded that a contiguous surface shaped by F14, Y15, E16, L18, and H19 in helix I, and N29, Q33, L35, and K36 in helix II is responsible for the binding.

Amino Acid Sequence↗
PubMed1998

[Parenchymatous cicatrix and urinary tract infection: physiopathology and clinical implications].

Renal scarring is the main long term complication of acute pyelonephritis in children. The prevalence rate is hazardous since data from the literature are confusing with respect to reflux nephropathy, chronic pyelonephritis and renal hypoplasia. The pathology of such lesions consists in focal interstitial fibrosis. When the first pyelonephritic attack occurs during infancy, renal growth may be compromised. The current approach of renal scar assessment is based on dimercaptosuccinic acid (DMSA) scan. Bilateral extensive lesions may be responsible for altered glomerular filtration rate (GFR) and/or arterial hypertension. The management of overt scarring is conservative and careful prevention must be based on early and aggressive treatment of acute pyelonephritis.

Child↗
PubMed1998

Determination of binding conformations of drugs to human serum albumin by transferred nuclear overhauser effect measurements and conformational analyses using high-temperature molecular dynamics calculations.

The binding conformations of oxyphenbutazone (OXY), Nepsilon-dansyl-L-lysine (DNS-LYS), and furosemide (FU) to human serum albumin (HSA) have been investigated by molecular dynamics (MD) calculations and transferred nuclear Overhauser effect (TRNOE) measurements. We have combined distance information obtained from the Conformational Analyzer with Molecular Dynamics And Sampling (CAMDAS) calculation and experimental NOE spectroscopy measurements to determine a "binding conformation" for each drug which binds to site I of HSA. For OXY, only one conformer (conf9) among the conformer set generated by MD calculation satisfied the distance restraint conditions obtained from TRNOE measurements. For DNS-LYS and FU, 17 and 5 conformers satisfied distance restraint conditions, respectively. The structure of conf9 of OXY was taken as a "template" to choose binding conformers for DNS-LYS and FU. By fitting the "template" to the 17 conformers of DNS-LYS and 5 conformers of FU, we could efficiently obtain one binding conformer for DNS-LYS (conf144) and FU (conf26). It is suggested from the feature of the binding conformation that the three-dimensional location of a hydrophobic aromatic ring, alkyl chain, and electronegative functional group is important for binding to site I of HSA. This method, which combines MD calculations and NOE information, is thought to be effective for determining the binding conformation of drugs to HSA.

Furosemide↗
PubMed1997

Solution structure of alpha-conotoxin MI determined by 1H-NMR spectroscopy and molecular dynamics simulation with the explicit solvent water.

The conformation of alpha-conotoxin MI, a potent antagonist of the nicotinic acetylcholine receptor, has been investigated in aqueous solution. Two-dimensional NMR experiments and simulated annealing calculations provide the overall topology of alpha-conotoxin MI; then molecular dynamics simulation with the explicit solvent water was followed in order to obtain a more reliable solution structure. The resulting conformation indicates the presence of a 3(10) helix and a type I beta-turn for residues Pro6-Cys8 and Gly9-Try12, respectively, and shows a significant structural similarity to that of alpha-conotoxin GI, which has biological activity similar to that of MI. The present study provides a molecular basis for the alpha-conotoxin-receptor interaction.

Computer Simulation↗
PubMed1996

Folding topologies of human interleukin-6 and its mutants as studied by NMR spectroscopy.

To understand the structure-function relationship in the human interleukin-6 (IL-6) system, comparative studies were performed on the basis of NMR data obtained using the wild-type IL-6 and six mutants. In each of the six mutants, either Leu152, Leu159, Leu166, Leu168, Leu175, or Leu182, which exist in the C-terminal receptor-binding region, was substituted with Val. The resonance assignments of Val, Ile, Leu, and Phe residues were made by using specific double-labeling and site-specific mutagenesis strategies. On the basis of chemical shift and NOE data collected for six IL-6 mutants and those for the wild-type IL-6, we analyzed the structural changes induced by the substitution of each of the six Leu residues. The NMR data showed that substitution of Leu182 with Val (L182V) induced no structural change in IL-6, suggesting that Leu182 is located on the surface of the IL-6 molecule. A significant decrease in receptor-binding activity was observed in the L182V mutant. It was concluded that the side chain of Leu182 is directly involved in receptor binding. Substitution of Leu175 with Val (L175V) was shown to induce a significant structural change in IL-6. The NMR data are discussed on the basis of the location of four helix elements and an up-up-down-down helix topology of the predicted structure of IL-6 [Bazan, J.F. (1991) Neuron 7, 197-208]. It is possible that helix D bent more sharply toward helix B in the L175V mutant than in the wild-type IL-6 to maintain a closely packed and solvent-inaccessible core formed in the mutated region. It is suggested that the kink of helix D is related to the decrease in receptor-binding activity in the L175V mutant. On the basis of the observed NOE network, the folding topology of IL-6 was analyzed. A comparison of the folding topology of IL-6 with that of human granulocyte colony-stimulating factor determined by X-ray crystallography [Hill, C. P., Osslund, T. D., & Eisenberg, D. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 5167-5171] indicated that IL-6 has a significant similarity of folding topology to that of human granulocyte colony-stimulating factor.

Amino Acid Sequence↗
PubMed1995

Three-dimensional solution structure of the calcium channel antagonist omega-agatoxin IVA: consensus molecular folding of calcium channel blockers.

The three-dimensional solution structure of omega-agatoxin IVA, which is a specific blocker of the P-type calcium channel isolated from funnel web spider venom and has a molecular mass of 5.2 kDa, was determined by two dimensional 1H NMR spectroscopy, combined with simulated annealing calculations. On the basis of 563 experimental constraints, including 516 distance constraints obtained from the nuclear Overhauser effect, 21 torsion angle (phi, chi 1) constraints, and 26 constraints associated with hydrogen bonds and disulfide bonds, a total of 14 converged structures were obtained. The atomic root mean square difference for the 14 converged structures with respect to the mean coordinates is 0.42 (+/- 0.07) A for the backbone atoms (N, C alpha, C) and 0.95 (+/- 0.15) A for all heavy atoms of the central part (residues 4 to 38) constrained by four disulfide bonds. The N- and C-terminal segments (residues 1 to 3 and 39 to 48, respectively) have a disordered structure in aqueous solution. The molecular structure of omega-agatoxin IVA is composed of a short triple-stranded antiparallel beta-sheet, three loops, and the disordered N- and C-terminal segments. The overall beta-sheet topology is +2x, -1, which is the same as that reported for omega-conotoxin GVIA, an N-type calcium channel blocker. Irrespective of differences in the number of disulfide bonds and low primary sequence homology, these two peptide toxins show a significant structural similarity in three dimensions. The whole-cell voltage-clamp recording using rat cerebellar slices suggests that the hydrophobic C-terminal segment of omega-agatoxin IVA, which does not exist in omega-conotoxin GVIA, plays a crucial role in the blocking action of omega-agatoxin IVA on the P-type calcium channel in rat cerebellar Purkinje cells. The present study provides a molecular basis for the toxin-channel interaction, and thereby provides insight into the discrimination of different subtypes of calcium channels.

Amino Acid Sequence↗
PubMed1995

[Enuresis and benign micturition disorders in childhood. II. Cost of the management].

The financial cost of bedwetting management is often underestimated. A study including 48 children aged 6 to 16 years was carried out in the outpatient clinic in order to evaluate the cost of these disorders during a 4 month-period. The diagnosis was the following: nocturnal enuresis (n = 15), bladder instability (n = 22) and other voiding dysfunction (n = 11). Our results showed that these expenses were quite important. A relationship between the kind of voiding dysfunction and the subsequent expenses was observed: the more complex was the disorder, the more expensive it was (average expenses = 1317 FF/year for nocturnal enuresis, 2506 FF/year for bladder instability and 3174 FF/year for other dysfunctions). Subsidiary expenses (transport, diapers and extrawashing) constituted an important part of the whole expenses: 46% in nocturnal enuresis, 42% in bladder instability and 38% in other dysfunctions.

Adolescent↗
PubMed1993

13C NMR study of the mode of interaction in solution of the B fragment of staphylococcal protein A and the Fc fragments of mouse immunoglobulin G.

The mode of interaction of the B domain (FB) of staphylococcal protein A and the Fc fragments of mouse immunoglobulin G (IgG) has been investigated by 13C NMR spectroscopy. Mouse IgG1, IgG2a, and IgG2b proteins have been selectively labeled with 13C at the carbonyl carbon of His, Met, Trp or Tyr residue and used to prepare the corresponding Fc fragments by limited proteolysis. Site-specific resonance assignments have been made for each of these Fc analogues. FB was reported to form two contacts (contact 1 and contact 2) with human Fc in the crystal [Biochemistry 20 (1981) 2361-2370]. Comparisons of the chemical shift data of the Fc fragments observed in the absence and presence of FB have led us to conclude that in solution contact 1 is responsible for the formation of the Fc-FB complexes.

Animals↗
PubMed1992

Three-dimensional solution structure of the B domain of staphylococcal protein A: comparisons of the solution and crystal structures.

The three-dimensional solution structure of the recombinant B domain (FB) of staphylococcal protein A, which specifically binds to the Fc portion of immunoglobulin G, was determined by NMR spectroscopy and hybrid distance geometry-dynamical simulated annealing calculations. On the basis of 692 experimental constraints including 587 distance constraints obtained from the nuclear Overhauser effect (NOE), 57 torsion angle (phi, chi 1) constraints, and 48 constraints associated with 24 hydrogen bonds, a total of 10 converged structures of FB were obtained. The atomic root mean square difference among the 10 converged structures is 0.52 +/- 0.10 A for the backbone atoms and 0.98 +/- 0.08 A for all heavy atoms (excluding the N-terminal segment from Thr1 to Glu9 and the C-terminal segment from Gln56 to Ala60, which are partially disordered). FB is composed of a bundle of three alpha-helices, i.e., helix I (Gln10-His19), helix II (Glu25-Asp37), and helix III (Ser42-Ala55). Helix II and helix III are antiparallel to each other, whereas the long axis of helix I is tilted at an angle of about 30 degrees with respect to those of helix II and helix III. Most of the hydrophobic residues of FB are buried in the interior of the bundle of the three helices. It is suggested that the buried hydrophobic residues form a hydrophobic core, contributing to the stability of FB.(ABSTRACT TRUNCATED AT 250 WORDS)

Amides↗