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K S Wilson

Publications and source records attributed to K S Wilson.

At least 19 recordsLinked to original sources
PubMed1992

Three-dimensional structure of catalase from Micrococcus lysodeikticus at 1.5 A resolution.

The three-dimensional crystal structure of catalase from Micrococcus lysodeikticus has been solved by multiple isomorphous replacement and refined at 1.5 A resolution. The subunit of the tetrameric molecule of 222 symmetry consists of a single polypeptide chain of about 500 amino acid residues and one haem group. The crystals belong to space group P4(2)2(1)2 with unit cell parameters a = b = 106.7 A, c = 106.3 A, and there is one subunit of the tetramer per asymmetric unit. The amino acid sequence has been tentatively determined by computer graphics model building and comparison with the known three-dimensional structure of beef liver catalase and sequences of several other catalases. The atomic model has been refined by Hendrickson and Konnert's least-squares minimisation against 94,315 reflections between 8 A and 1.5 A. The final model consists of 3,977 non-hydrogen atoms of the protein and haem group, 426 water molecules and one sulphate ion. The secondary and tertiary structures of the bacterial catalase have been analyzed and a comparison with the structure of beef liver catalase has been made.

Amino Acid Sequence↗
PubMed1992

Crystallization and preliminary X-ray analysis of the complex between a mouse Fab fragment and a single IgG-binding domain from streptococcal protein G.

The Fab fragment of a mouse immunoglobulin G1, complexed with a single IgG-binding domain from streptococcal protein G, has been crystallized in a form suitable for analysis by X-ray diffraction. The needle-shaped crystals were grown from polyethylene glycol 4000 using vapour diffusion methods and diffract to 2.3 A resolution. The space group is P2(1)2(1)2(1) (a = 64.5 A, b = 70.5 A and c = 120.1 A), with one Fab-protein G domain complex in the asymmetric unit. Solution of the three-dimensional structure of the complex will permit a detailed analysis of the molecular interactions between protein G and the Fab portion of IgG.

Animals↗
PubMed1992

Active site structure of methylamine dehydrogenase: hydrazines identify C6 as the reactive site of the tryptophan-derived quinone cofactor.

To identify the reactive part of the orthoquinone function of the tryptophan-derived cofactor found in methylamine dehydrogenase (MADH), we have determined the crystal structures of MADH from Thiobacillus versutus inhibited by methylhydrazine and (2,2,2-trifluoroethyl)hydrazine. Extra electron density attached to C6 of the tryptophyl tryptophanquinone cofactor shows that this atom and not C7 is the reactive part of the ortho-quinone moiety. The density retained after hydrazine inhibition is much less extensive than expected, however, suggesting that partial breakdown of the inhibitors after reaction with the cofactor may take place. A detailed description is presented of the cofactor environment in an improved model of MADH which now includes information from the recently determined gene sequence of the cofactor-containing subunit [Ubbink, M., van Kleef, M.A.G., Kleinjan, D., Hoitink, C.W.G., Huitema, F., Beintema, J.J., Duine, J.A., & Canters, G.W. (1991) Eur. J. Biochem. 202, 1003-1012]. We hypothesize that Asp76 is responsible for proton abstraction from the alpha-carbon of the substrate during catalysis.

Amino Acid Sequence↗
PubMed1992

High-resolution X-ray structures of pig metmyoglobin and two CD3 mutants: Mb(Lys45----Arg) and Mb(Lys45----Ser).

The structure of pig aquometmyoglobin has been refined to a crystallographic R-factor of 19.8% against X-ray diffraction data between 10- and 1.75-A spacing. The final structural model comprises two molecules of pig myoglobin, 233 water molecules, and two sulfate ions. A water molecule is coordinated to each of the heme iron atoms with an average Fe-OH2 bond distance of 2.19 A, and the mean Fe-N epsilon (proximal histidine-93) distance is 2.20 A. In contrast to the structure of sperm whale metmyoglobin, the iron is not significantly displaced from the plane of the heme. At the entrance to the heme pocket, the side-chain amino group of lysine-45 (CD3) is well-defined in the electron density map and forms salt-bridging interactions with the heme 6-propionate and with a sulfate ion. Serine and arginine replacements have been made previously at position 45 to examine the proposal that the CD3 side chain acts as a barrier to ligand entry into the protein. Crystal structures of the arginine-45 and serine-45 mutant metmyoglobins have been solved to 1.9 and 2.0 A resolution, respectively. In both cases the structural changes are confined to the site of mutation. Arginine-45 takes up a conformation closely similar to that observed for this residue in wild-type sperm whale myoglobin, in which it makes more extensive charge-charge and charge-dipole interactions and appears to restrict the movement of the distal histidine away from the ligand. The hydroxyl group of serine-45 is disordered, but it is clear that the effect of the mutation is to open up the solvent-exposed face of the heme pocket.

Animals↗
PubMed1992

Initiating a crystallographic study of a class II fructose-1,6-bisphosphate aldolase.

We have reproducibly crystallized the metal-dependent Class II fructose-1,6-bisphosphate aldolase from Escherichia coli. Crystals in the shape of truncated hexagonal bipyramids have unit cell dimensions of a = b = 78.4 A, c = 290.6 A and are suitable for a detailed structural analysis. The space group has been identified as P6(1)22 or enantiomorph. Data sets to approximately 2.9 A resolution have been recorded using both the Rigaku R-AXIS IIc image plate area detector coupled to a copper target rotating anode X-ray source and using the MAR image plate systems with synchrotron radiation at the EMBL outstation DESY in Hamburg, and at S.R.S. Daresbury. Diffraction beyond 2.5 A has been observed when large freshly grown crystals are used with the synchrotron beam. A data set to this resolution has been collected. Several putative heavy-atom derivative data sets have also been measured using synchrotron radiation facilities and analysis of these data sets is in progress.

Crystallization↗
PubMed1992

Crystal structure of NAD-dependent formate dehydrogenase.

The ternary complex of NAD-dependent formate dehydrogenase (FDH) from the methylotrophic bacterium Pseudomonas sp. 101 (enzyme-NAD-azide) has been crystallised in the space group P2(1)2(1)2(1) with cell dimensions a = 11.60 nm, b = 11.33 nm, c = 6.34 nm. There is 1 dimeric molecule/asymmetric unit. An electron density map was calculated using phases from multiple isomorphous replacement at 0.30 nm resolution. Four heavy atom derivatives were used. The map was improved by solvent flattening and molecular averaging. The atomic model, including 2 x 393 amino acid residues, was refined by the CORELS and PROLSQ packages using data between 1.0 nm and 0.30 nm excluding structure factors less than 1 sigma. The current R factor is 27.1% and the root mean square deviation from ideal bond lengths is 4.2 pm. The FDH subunit is folded into a globular two-domain (coenzyme and catalytic) structure and the active centre and NAD binding site are situated at the domain interface. The beta sheet in the FDH coenzyme binding domain contains an additional beta strand compared to other dehydrogenases. The difference in quaternary structure between FDH and the other dehydrogenases means that FDH constitutes a new subfamily of NAD-dependent dehydrogenases: namely the P-oriented dimer. The FDH nucleotide binding region of the structure is aligned with the three dimensional structures of four other dehydrogenases and the conserved residues are discussed. The amino acid residues which contribute to the active centre and which make contact with NAD have been identified.

Amino Acid Sequence↗
PubMed1992

The polypeptide chain fold in tyrosine phenol-lyase, a pyridoxal-5'-phosphate-dependent enzyme.

The tyrosine phenol lyase (EC 4.1.99.2) from Citrobacter intermedius has been crystallised in the apo form by vapour diffusion. The space group is P2(1)2(1)2. The unit cell has dimensions a = 76.0 A, b = 138.3 A, c = 93.5 A and it contains two subunits of the tetrameric molecule in the asymmetric unit. Diffraction data for the native enzyme and two heavy atom derivatives have been collected with synchrotron radiation and an image plate scanner. The structure has been solved at 2.7 A resolution by isomorphous replacement with subsequent modification of the phases by averaging the density around the non-crystallographic symmetry axis. The electron density maps clearly show the relative orientation of the subunits and most of the trace of the polypeptide chain. Each subunit consists of two domains. The topology of the large domain appears to be similar to that of the aminotransferases.

Chemical Phenomena↗
PubMed1992

Crystal structure of a dUTPase.

The enzyme dUTPase catalyses the hydrolysis of dUTP and maintains a low intracellular concentration of dUTP so that uracil cannot be incorporated into DNA. dUTPase from Escherichia coli is strictly specific for its dUTP substrate, the active site discriminating between nucleotides with respect to the sugar moiety as well as the pyrimidine base. Here we report the three-dimensional structure of E. coli dUTPase determined by X-ray crystallography at a resolution of 1.9 A. The enzyme is a symmetrical trimer, and of the 152 amino acid residues in the subunit, the first 136 are visible in the crystal structure. The tertiary structure resembles a jelly-roll fold and does not show the 'classical' nucleotide-binding domain. In the quaternary structure there is a complex interaction between the subunits that may be important in catalysis. This possibility is supported by the location of conserved elements in the sequence.

Amino Acid Sequence↗
PubMed1992

Refinement of rubredoxin from Desulfovibrio vulgaris at 1.0 A with and without restraints.

X-ray data have been recorded from crystals of rubredoxin derived from the bacterium Desulfovibrio vulgaris to a resolution of 1.0 A using in part synchrotron radiation and in part X-rays from a sealed-tube Mo K alpha source. In both cases an imaging-plate scanner was used as detector. The space group of the crystals is P2(1) with cell dimensions a = 19.97, b = 41.45, c = 24.41 A and beta = 108.3 degrees. The overall merging R(I) factor between symmetry-related reflections was 5.8%. The model was refined by least-squares minimization initially with stereochemical restraints to an R factor of 16.4%. Only atomic positional parameters and isotropic temperature factors for non-H atoms were used in the refinement. There were 18,532 independent X-ray observations for a total of 1916 atomic parameters. A round of unrestrained refinement gave an R factor of 16.0%, acceptable geometry for more than 90% of the protein atoms, but emphasized the disorder inherent in eight of the residues. A final round of restrained refinement gave an R factor of 14.7%. Three of the 389 protein atoms in the molecule, in the side chain of Lys2, have been assigned zero occupancy in the model. A total of eight atoms in three side chains have been assigned two conformations, giving 393 protein atomic sites in the model. In addition there is one Fe atom, a sulfate ion and 102 water sites. 339 H atoms were included at their calculated positions, which were not refined. There is clear evidence for anisotropic thermal motion. This has not been incorporated in the present model.

Crystallization↗
PubMed1992

Spectroscopic studies on proteinase K and subtilisin DY. Relation to X-ray models.

Circular dichroic spectroscopy has been used to study the effect of pH, guanidinium hydrochloride concentration and temperature on the conformation of the fungal subtilisin-like proteinase K and the bacterial DY. The ellipticity of the bands in the far ultraviolet region remains almost unchanged in the pH range 3.0-11.0 (PMS-proteinase K) and 5.0-10.0 (PMS-subtilisin DY). The same ranges of pH stability were determined from the pH dependence of the near ultraviolet dichroic spectra. Hence the changes in the tertiary and secondary structure occur in parallel. Proteinase K is considerably more stable at acidic and somewhat more stable at alkaline pH than subtilisin DY. At neutral pH proteinase K is more resistant to denaturation by guanidinium hydrochloride than is subtilisin DY. The midpoints of the denaturation curves were 6.2 M and 3.2 M guanidinium, respectively. The thermal unfolding of proteinase K occurred at a higher temperature than for subtilisin DY, the transition midpoints being 65 degrees and 48 degrees, respectively. Thus proteinase K is overall a much more robust molecule than subtilisin DY, showing greater resistance to all three forms of denaturation. The differences in the stability of the two proteinases can be partly explained by differences in their calcium binding sites.

Circular Dichroism↗
PubMed1992

Uvulopalatopharyngoplasty for obstructive sleep apnea: a community's experience.

Uvulopalatopharyngoplasty (UPPP) has become an accepted method for treating obstructive sleep apnea (OSA), with a reported success rate as high as 77%, depending upon inclusionary and outcome criteria. The authors reviewed the records of 90 patients with moderately severe OSA (apnea plus hypopnea index [AHI] greater than 20) who underwent UPPP at either a private community or an academic hospital. Forty percent of patients experienced more than a 50% reduction in their AHI with UPPP. Only 22 (24%) of the patients had a postoperative AHI less than 50% of the preoperative AHI and less than 20, i.e., met the authors' criteria for surgical success. The success rate for community otolaryngologists was no different than that achieved in the academic institution. When data from previously published reports were analyzed using these criteria for success, similar results were observed. This study suggests that the effectiveness of UPPP performed by the general otolaryngologic community is equivalent to that reported in the literature. However, more rigorous criteria must be applied to UPPP when evaluating its results and in counseling potential candidates for this procedure.

Adult↗
PubMed1992

Primary cutaneous malignant melanoma: experience of the British Columbia Cancer Agency from 1972 to 1981.

A retrospective review of 891 patients with newly diagnosed primary cutaneous malignant melanoma (CMM) registered at the British Columbia Cancer Agency from 1972 to 1981 is presented. Age-standardized incidence rates in British Columbia have increased markedly over that time. The female-to-male ratio was 1.13:1 and the median age overall was 47 years. A change in the size of a mole was the most common presenting sign (in 43% of patients) and the median duration of signs was 5.9 months. Predominant tumour sites were the trunk for males and the lower limbs for females. Dominant growth patterns were superficial spreading melanoma (65%), nodular melanoma (25%), lentigo maligna melanoma (5%) and acral lentiginous melanoma (2%). On staging of the primary tumour, 90% of patients had local disease, 9% of patients had regional disease and 1% of patients had distant disease at presentation. Median depths of tumours were 1.45 mm for males and 1.10 mm for females; no T1 tumours (tumours 0.75 mm or less in depth [TNM classification]) were staged beyond the local area. Disease recurred in 44% of males and 32% of females. The 15-year survival rate was 55.5% for males and 70.3% for females. These findings are compared with those of recent international series. It is apparent that earlier diagnosis improves survival and that more education is needed in view of the increasing incidence and death from CMM.

Adolescent↗
PubMed1992

Elective and therapeutic regional lymph node dissection for cutaneous malignant melanoma: experience of the British Columbia Cancer Agency, 1972 to 1981.

The authors present a 10-year review of patients registered at the British Columbia Cancer Agency (BCCA) who underwent lymph node dissection for malignant melanoma. Pathological findings in the regional lymph nodes were correlated with primary site, growth pattern, depth of invasion and Clark's level. Elective lymph node dissection (ELND) was performed in 223 patients, and the overall positivity rate (pathologically involved nodes) was 16%. Survival rates for patients who had ELND were compared with those for BCCA patients not having had ELND and patients from the University of Sydney, Sydney, Australia. Although patients who underwent ELND had thicker and more frequently ulcerated primary tumours than patients with stage I disease who did not undergo ELND, survival was better in the group who had ELND. However, when all potential prognostic factors were analysed by multivariate analysis, ELND was not a significant factor in prognosis. Therapeutic lymph node dissection (TLND) was performed in 50 patients at the time the primary tumour was diagnosed, and involvement of the lymph nodes was found in 36. Of 525 patients with clinical stage I disease who did not have ELND, disease recurred in the regional lymph nodes in 119; 86 of them had TLND for recurrence (RTLND). Median survival rates from the time of diagnosis of the primary lesion for ELND-positive, TLND-positive and RTLND patients were 4.2, 2.7 and 4.4 years respectively; the differences were not significant. New treatments are required for patients with involved regional lymph nodes.

British Columbia↗
PubMed1979

Ewing sarcoma: phalangeal primary with fatal cardiac metastases.

A 39-year-old man had pain and swelling of the terminal phalanx of a finger. Radiograph was interpreted as osteomyelitis, and amputation through the mid-phalanx was performed. Histology revealed Ewing sarcoma. Lung metastases rapidly developed. Right lung irradiation and systemic chemotherapy, including doxorubicin, were instituted. He developed progressive severe right ventricular failure which was attributed to effects of large pulmonary metastases. Autopsy showed massive right ventricular metastases, the primary pathological cause of the heart failure, without evidence of doxorubicin cardiomyopathy.

Adult↗