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U Baumann

Publications and source records attributed to U Baumann.

At least 55 records · Page 3Linked to original sources
PubMed1998

Purification, crystallization and preliminary X-ray analysis of human recombinant cytosolic serine hydroxymethyltransferase.

As an enzyme of the thymidylate synthase cycle, serine hydroxymethyltransferase (SHMT) has a key role in nucleotide biosynthesis. Elevated activities of SHMT have been correlated with the increased demand for nucleotide biosynthesis in tumors of human and rodent origin, making this enzyme a novel target for cancer chemotherapy. Here the purification and crystallization of recombinant human cytosolic SHMT are reported. Crystals belong to space group P6222 or P6422 with cell parameters a = b = 155.0, c = 235.5 A and diffract to at least 3.0 A resolution.

Crystallization↗
PubMed1998

[Predictability of pain after laparoscopic cholecystectomy with self-efficacy and locus of control].

UNLABELLED: The study consists of a prospective randomized controlled clinical trial of patients undergoing laparoscopic cholecystectomy. Besides medical and sociodemographic data, two personality factors--self-efficacy and locus of control--were found to predict postoperative pain. Self-efficacy describes the expectations of a person to successfully execute the behavior required to produce behavioral outcomes. Locus of control, in the extreme case, is a personality factor which is represented by an internal orientation in which the individual believes that rewards are brought about by his own action, versus an external orientation, in which the individual believes that rewards are the result of powerful others or chance factors and fate. We postulate that the two personality factors correlate with postoperative parameters of pain and that there are also multiple correlations between them. METHODS: For the two personality factors we applied two questionnaires which were given to the patients preoperatively. One is well established and the second one was developed and tested especially for this study by us. We used subjective pain, demand for and quantity of analgetics as parameters of postoperative pain until the 3rd day after surgery. RESULTS: The statistical analysis of 56 patients revealed that the two personality factors proved to be the most relevant and significant factors (p<0.05-0.001) to predict and also to explain high rate of variance up to 60% of postoperative pain. Patients with a high expectation of self-efficacy in pain management and an internal locus of control had a significantly lower subjective pain, demand for and quantity of analgetics than patients with low expectations of self-efficacy or a high external orientation with chance factor and fate in control. Medical and sociodemographic variables did not predict any parameters of pain. Some surgical factors were kept constant. DISCUSSION: These findings underline the importance of personality factors also in postoperative pain, which can be predicted by self-efficacy and locus of control. This result means for us that self-efficacy and locus of control influence the cognates of personal pain perception within the context of the individual history of experiences and seem to be changeable preoperatively by special psychological training.

Clinical Trial↗
PubMed1997

[Reference curves for hearing surface scaling in clinical use].

METHODS: A commercially available system for the purpose of categorial loudness rating (WHF, WESTRA ELECTRONIC GmbH, Wertingen) was applied with 57 subjects with normal hearing to evaluate reference loudness level functions for 1/3-octave bandpass filtered noise and octave bandpass filtered environmental sounds. RESULTS: The procedure can be carried out with high reproducibility without effects of training due to repetition and only slight influence of subject sex, whereas the labeling of input device and temporal structure of the environmental sounds influence results, as does the center frequency. CONCLUSIONS: Our results showed deviations compared with the reference functions displayed in the WHF system.

Adolescent↗
PubMed1997

[Interview and questionnaire of social support and social assistance SONET].

The present paper introduces into the structures, psychometric properties and the development of the "Interview on the Social Network and Social Support SONET". SONET is a network-analytical tool based on conceptual and methodological considerations related to the concepts of social network and social support. It was developed by the authors over the last few years. Discussing the most important results on its psychometric properties shows that SONET has good reliability, and acceptably high proof of its validity. Relative to rehabilitation of psychiatric and somatic disorders, SONET may be used in the diagnosis of deficits in social integration and interpersonal relationships of an individual. Additionally, stressful conditions of interpersonal relationships are assessed as well. SONET is also suitable for evaluating rehabilitative interventions at the level of personal relationships. Because no single-case studies have been conducted with the instrument until now, the paper concludes by presenting results from a small sample of schizophrenic and depressive patients demonstrating its applicability for diagnostic, prognostic and evaluative problems in the field of rehabilitation.

Adult↗
PubMed1996

Enzyme flexibility, solvent and 'weak' interactions characterize thrombin-ligand interactions: implications for drug design.

BACKGROUND: The explosive growth in the rate of X-ray determination of protein structures is fuelled largely by the expectation that structural information will be useful for pharmacological and biotechnological applications. For example, there have been intensive efforts to develop orally administrable antithrombotic drugs using information about the crystal structures of blood coagulation factors, including thrombin. Most of the low molecular weight thrombin inhibitors studied so far are based on arginine and benzamidine. We sought to expand the database of information on thrombin-inhibitor binding by studying new classes of inhibitors. RESULTS: We report the structures of three new inhibitors complexed with thrombin, two based on 4-aminopyridine and one based on naphthamidine. We observe several geometry changes in the protein main chain and side chains which accompany inhibitor binding. The two inhibitors based on 4-aminopyridine bind in notably different ways: one forms a water-mediated hydrogen bond to the active site Ser195, the other induces a rotation of the Ser214-Trp215 peptide plane that is unprecedented in thrombin structures. These binding modes also differ in their 'weak' interactions, including CH-O hydrogen bonds and interactions between water molecules and aromatic pi-clouds. Induced-fit structural changes were also seen in the structure of the naphthamidine inhibitor complex. CONCLUSIONS: Protein flexibility and variable water structures are essential elements in protein-ligand interactions. Ligand design strategies that fail to take this into account may overlook or underestimate the potential of lead structures. Further, the significance of 'weak' interactions must be considered both in crystallographic refinement and in analysis of binding mechanisms.

4-Aminopyridine↗
PubMed1996

Biases and balances within the genetic code.

Encoding sequences show distinct nucleotide compositions within the individual codon positions, termed the position-specific nucleotide frequencies. The increased amounts of sequence data for human and E. coli are evaluated for the position-specific composition of all four nucleotides as well as the subgroups S and R. A, G and S reveal a pronounced position-specific pattern. These nucleotide biases are partially known; the characteristic A pattern was not reported before. Biases in position 31 and 2 are predominantly caused by amino acid composition of proteins. The biases in third positions are proposed to be driven by the tendency of compensation leading to statistical gross nucleotide content of coding sequences. Possible applications of position-specific frequencies are used as a phylogenetic marker or as a basis of coding measures.

Animals↗
PubMed1995

Crystal structure of a complex between Serratia marcescens metallo-protease and an inhibitor from Erwinia chrysanthemi.

The crystal structure of the complex between the 50 kDa metallo-endoproteinase from Serratia marcescens (SMP), a member of the metzincin superfamily, and an inhibitor from Erwinia chrysanthemi (Inh) was solved by molecular replacement using the known structure of SMP, and refined at 2.30 A resolution to a crystallographic R-factor of 0.195. The E. chrysanthemi inhibitor folds into a compact eight-stranded antiparallel beta-barrel of simple up-down topology such as is found for members of the retinol binding protein family. It mainly interacts with the protease via its five N-terminal residues, which insert into the active site cleft, occupying the S' sites. The first N-terminal residue, SerI1, is partially cleaved off by the protease, while SerI2 makes a hydrogen bond with the catalytically active glutamic acid, Glu177, of the protease. Further interactions are made between one face of the inhibitor formed by the strands s3, s4 and s5 and the protease segment 218 to 228, which is located immediately after the characteristic "Met-turn" of the metzincins.

Amino Acid Sequence↗
PubMed1995

The metzincins--topological and sequential relations between the astacins, adamalysins, serralysins, and matrixins (collagenases) define a superfamily of zinc-peptidases.

The three-dimensional structures of the zinc endopeptidases human neutrophil collagenase, adamalysin II from rattle snake venom, alkaline proteinase from Pseudomonas aeruginosa, and astacin from crayfish are topologically similar, with respect to a five-stranded beta-sheet and three alpha-helices arranged in typical sequential order. The four proteins exhibit the characteristic consensus motif HEXXHXXGXXH, whose three histidine residues are involved in binding of the catalytically essential zinc ion. Moreover, they all share a conserved methionine residue beneath the active site metal as part of a superimposable "Met-turn." This structural relationship is supported by a sequence alignment performed on the basis of topological equivalence showing faint but distinct sequential similarity. The alkaline proteinase is about equally distant (26% sequence identity) to both human neutrophil collagenase and astacin and a little further away from adamalysin II (17% identity). The pairs astacin/adamalysin II, astacin/human neutrophil collagenase, and adamalysin II/human neutrophil collagenase exhibit sequence identities of 16%, 14%, and 13%, respectively. Therefore, the corresponding four distinct families of zinc peptidases, the astacins, the matrix metalloproteinases (matrixins, collagenases), the adamalysins/reprolysins (snake venom proteinases/reproductive tract proteins), and the serralysins (large bacterial proteases from Serratia, Erwinia, and Pseudomonas) appear to have originated by divergent evolution from a common ancestor and form a superfamily of proteolytic enzymes for which the designation "metzincins" has been proposed. There is also a faint but significant structural relationship of the metzincins to the thermolysin-like enzymes, which share the truncated zinc-binding motif HEXXH and, moreover, similar topologies in their N-terminal domains.

Amino Acid Sequence↗
PubMed1995

[Clinical screening after thyroid gland diseases: contribution of orienting ultrasound examination].

AIM: Of this study was to define the significance of approximate ultrasound explorations of the thyroid gland for the clinical screening for thyroid diseases. METHOD: 918 patients in the medical service of a general hospital were screened for thyroid diseases by means of clinical, functional and sonomorphological methods. A sonographic screening scan with a 5 MHz probe provided data concerning structure and dimension of thyroid gland. Maximal sagittal diameter (SDm, normal range < 18 mm) was taken as a measure for thyroid size. RESULTS: Echogenicity has no essential meaning for thyroid dysfunction screening, but is indispensable for the detection of circumscript or general echo deficiency. SDm has proved to be a simple and well reproducible measure for thyroid size. Among 41 patients with thyrotoxicosis 40 had enlarged SDm, which means a sensitivity of 97.6%. However, a high rate of false positives makes TSH-screening of all enlarged thyroid glands obligatory. Moreover, SDm allows the estimation of a lack of thyroid mass as the most common cause of hypothyroidism. CONCLUSION: We recommend that an approximate ultrasound exploration of the thyroid gland including measuring of SDm should be part of every diagnostic procedure for thyroid disease, as it is precise and not time consuming.

Adult↗
PubMed1994

Crystal structure of the 50 kDa metallo protease from Serratia marcescens.

The crystal structure of the 50 kDa metalloprotease from the Gram-negative bacterium Serratia marcescens has been solved and refined to a crystallographic R-factor of 0.192 at 1.80 A resolution. The structure is very similar to that of alkaline protease from Pseudomonas aeruginosa, in particular the calcium binding "parallel beta roll" motif is completely conserved. The N-terminal proteolytic domain shows the typical "metzincin" fold. The active sites of the two enzymes are slightly different, Tyr216 is a Zn ligand in the Serratia metallo protease. The loops 70-77 and 122-132, which encompass the active site cleft, differ due to insertions and deletions so that the Serratia metallo protease seems to have a more open site than the alkaline protease.

Amino Acid Sequence↗
PubMed1993

Three-dimensional structure of the alkaline protease of Pseudomonas aeruginosa: a two-domain protein with a calcium binding parallel beta roll motif.

The three-dimensional structure of the alkaline protease of Pseudomonas aeruginosa, a zinc metalloprotease, has been solved to a resolution of 1.64 A by multiple isomorphous replacement and non-crystallographic symmetry averaging between different crystal forms. The molecule is elongated with overall dimensions of 90 x 35 x 25 A; it has two distinct structural domains. The N-terminal domain is the proteolytic domain; it has an overall tertiary fold and active site zinc ligation similar to that of astacin, a metalloprotease isolated from a European freshwater crayfish. The C-terminal domain consists of a 21-strand beta sandwich. Within this domain is a novel 'parallel beta roll' structure in which successive beta strands are wound in a right-handed spiral, and in which Ca2+ ions are bound within the turns between strands by a repeated GGXGXD sequence motif, a motif that is found in a diverse group of proteins secreted by Gram-negative bacteria.

Amino Acid Sequence↗
PubMed1993

Three stages in the evolution of the genetic code.

A diversification of the genetic code based on the number of codons available for the proteinous amino acids is established. Three groups of amino acids during evolution of the code are distinguished. On the basis of their chemical complexity those amino acids emerging later in a translation process are derived. Codon number and chemical complexity indicate that His, Phe, Tyr, Cys and either Lys or Asn were introduced in the second stage, whereas the number of codons alone gives evidence that Trp and Met were introduced in the third stage. The amino acids of stage 1 use purine-rich codons, while all the amino acids introduced in the second stage, in contrast, use pyrimidines in the third position of their codons. A low abundance of pyrimidines during early translation is derived. This assumption is supported by experiments on non-enzymatic replication and interactions of hairpin loops with a complementary strand. A back extrapolation concludes a high purine content of the first nucleic acids, which gradually decreased during their evolution. Amino acids independently available from prebiotic synthesis were thus correlated to purine-rich codons. Implications on the prebiotic replication are discussed also in the light of recent codon usage data.

Amino Acids↗
PubMed1993

Tempe fermentation: some aspects of formation of gamma-linolenic acid, proteases and vitamins.

During a tempe fermentation the concentrations of linoleic, and alpha-linolenic acids (ALA) decreased while the concentration of oleic acid increased. During fatty acid synthesis Rhizopus sp. produced only gamma-linolenic acid (GLA) instead of ALA. The amount of GLA in tempe were influenced by varying external parameters. The proteolytic capacity of 36 strains of the genus Rhizopus isolated from Indonesian tempe or tempe inocula was examined. There was a distinct increase in the amount of free amino acids during tempe fermentation. Fermentations with mixed populations of bacteria and Rhizopus yielded a lower level of free amino acids, but an increase in total amount of amino acids. In comparison to intracellular, and extracellular proteases the proteases of the cell wall fraction are most responsible for proteolytic capacity of the different Rhizopus strains. Two isolated strains of Citrobacter freundii were found to be the best vitamin B(12) producers during the soaking of soybeans. In the solid substrate fermentation the Rhizopus molds formed vitamin B(6), riboflavin, and nicotinic acid. The addition of bacteria to the solid substrate fermentation resulted in a strong increase of active vitamin B(12) in tempe. In the presence of the Rhizopus mold, the vitamin B(12) formation by C. freundii was three times higher than that of a fermentation without the mold.

Journal Article↗
PubMed1993

The molecular basis of alpha 1-antichymotrypsin deficiency in a heterozygote with liver and lung disease.

Alpha 1-antichymotrypsin (alpha 1-ACT) is a serine proteinase inhibitor (serpin) with cathepsin G, mast cell chymase and chymotrypsin as target enzymes. We present the case of a middle-aged man with low plasma levels of alpha 1-ACT, asthma with progression to emphysema, and chronic HCV positive liver disease with selective accumulation of alpha 1-ACT in hepatocytes. This secretory defect is analogous to that seen in Pi Z alpha 1-antitrypsin deficiency. The molecular basis of alpha 1-ACT deficiency in this patient has been characterized by direct sequencing of the alpha 1-ACT genes from the patient and his father. A C-->G transversion in exon III causing a 229Pro-->Ala substitution is proposed to cause a conformational change resulting in abnormal transport through the RER. This mutation was found in one of 20 additional tested patients with chronic obstructive lung disease, but in no control. Two additional polymorphisms of the gene have been identified in unrelated healthy individuals with normal plasma alpha 1-ACT levels. The alpha 1-ACT deficiency state may predispose to obstructive lung disease and influence the course of liver disease. Identification of a specific mutation allows identification of heterozygotes for this deficiency allowing future evaluation of its clinical significance.

Amino Acid Sequence↗
PubMed1993

The irregular chiasm C-roughest locus of Drosophila, which affects axonal projections and programmed cell death, encodes a novel immunoglobulin-like protein.

The axonal projection mutations irregular chiasm C of Drosophila melanogaster comap and genetically interact with the roughest locus, which is required for programmed cell death in the developing retina. We cloned the genomic region in 3C5 by transposon tagging and identified a single transcription unit that produces a major, spatially and temporally regulated mRNA species of approximately 5.0 kb. Postembryonic expression is strong in the developing optic lobe and in the eye imaginal disc. The gene encodes a transmembrane protein of 764 amino acids with five extracellular immunoglobulin-like domains and similarity to the chicken axonal surface glycoprotein DM-GRASP/SC1/BEN. Both known irreC alleles reduce the level of transcription, whereas the roughestCT mutation disrupts the intracellular domain of the protein.

Alleles↗