PubMed Health⌕ Search

Biomedical subjects

W Henkel

Publications and source records attributed to W Henkel.

At least 19 recordsLinked to original sources
PubMed1999

Synthesis and folding of native collagen III model peptides.

Solid-phase synthesis of triple-helical peptides, including native collagen III sequences, was started with a trimeric branch, based upon the lysine dipeptide [Fields, C. G., Mickelson, D. J., Drake, S. L., McCarthy, J. B., and Fields, G. B. (1993) J. Biol. Chem. 268, 14153-14160]. Branch synthesis was modified, using TentaGel R as resin, p-hydroxybenzyl alcohol (HMP) as linker, Dde as N(epsilon)-protective group, and HATU/HOAT as coupling reagent. Three homotrimeric sequences, each containing the Gly 606-Gly 618 portion of human type III collagen, were added to the amino functions of the branch. The final incorporation of GlyProHyp triplets, stabilizing the collagen III triple helix, was performed by using protected GlyProHyp tripeptides, each containing tert-butylated hydroxyproline [P(tBu)] instead of hydroxyproline (P). Among the protected tripeptides FmocP(tBu)PG, FmocPP(tBu)G, and FmocGPP(tBu), prepared manually on a chlorotrityl resin, incorporation of FmocPP(tBu)Gly was best suited for synthesis of large and stable peptides, such as PPG(8), containing 8 (PPG)(3) trimers (115 residues, 10 610 Da). The structures of five peptides, differing from each other by the type and number of the triplets incorporated, were verified by MALDI-TOF-MS. Their conformations and thermodynamic data were studied by circular dichroism and differential scanning calorimetry. Except for PPG(8), containing 8 (PPG)(3) trimers with hydroxyproline in the X position and adopting a polyproline II structure, all peptides were triple-helical in 0.1 M acetic acid and their thermal stabilities ranged from t(1/2) = 39. 4 to t(1/2) = 62.5 degrees C, depending on the identity and number of the triplets used. Similar values of the van't Hoff enthalpy, DeltaH(vH), derived from melting curves, and the calorimetric enthalpy, DeltaH(cal), obtained from heat capacity curves, indicate a cooperative ratio of CR = DeltaH(vH)/DeltaH(cal) = 1, establishing a two-state process for unfolding of THP(III) peptides. The independence of the transition temperatures t(1/2) on peptide concentration as well as equilibrium centrifugation data indicate monomolecular dimer(f) to dimer(u) (F(2) <--> U(2)) transitions and, in addition, bimolecular dimer(f) to monomer(u) transitions (F(2) <--> 2U). The dominance of the concentration-independent monomolecular reaction over the concentration-dependent bimolecular reaction makes thermal unfolding of THP(III) peptides appear to be monomolecular. If one designates the molecularity described by the term pseudomonomolecular, unfolding of the dimeric peptides PPG(6-8) follows a two-state, pseudomonomolecular reaction.

Amino Acid Sequence↗
PubMed1996

Cross-link analysis of the C-telopeptide domain from type III collagen.

Several peptides were isolated from tryptic digests of insoluble calf aorta matrix by chromatography. Reductive pyridylethylation of a tryptic 15 kDa pool released fragments deriving from the C-terminus of type III collagen. A 50-residue peptide Tc(III) was shown by sequence analysis to be the C-terminal peptide from the alpha 1(III)-chain, containing a helical and non-helical region of equal sizes. The peptide was further digested with collagenase to give Colc(III), comprising the complete C-terminal non-helical region of alpha 1(III) including a hydroxylysine in position 16c. The peptide Tc(III) x TN(III) was isolated, demonstrating covalent cross-linking between the C-terminal non-helical region of one type III molecule and the N-terminal helical cross-linking region of another. Its digestion with cyanogen bromide yielded the small fragments alpha 1(III)CB3B* and alpha 1(III)CB3C, confirming TN(III) as an N-terminal helical crosslink site. Sequence analysis of both Tc(III) x TN(III) and its collagenase-derived cross-linked peptide Colc(III) x TN(III) established the 4D-staggered alignment of adjacent collagen III molecules. The cross-link structure of both peptides was mainly dihydroxylysinonorleucine with a small amount of hydroxylysinonorleucine, indicating that the lysine residues involved in formation of the cross-links are both hydroxylated. No pyridinoline or histidinohydroxylysinonorleucine cross-links were found within the non-reduced C-telopeptide region of type III collagen.

Amino Acid Sequence↗
PubMed1993

Growth in serum-free medium improves isolation of Chlamydia pneumoniae.

Infectivity titers were determined for eight Chlamydia pneumoniae strains simultaneously grown in serum-free and serum-supplemented cell culture media. Use of serum-free medium resulted in a 10- to 50-fold increase in the susceptibility of HL cells to chlamydial infection. Comparative primary isolation of a wild-type strain also produced higher inclusion counts in a serum-free environment. Serum-free cultivation is recommended to increase the efficiency of C. pneumoniae isolation from clinical material and to permit elementary body purification without interference caused by serum components.

Chlamydophila pneumoniae↗
PubMed1990

[Occupational anamnesis of patients with selected diseases].

The occupational anamneses of 400 patients of the Martin-Luther-Universität with the Diagnoses idiopathic hip-head necrosis, melanoma, basaloma as well as larynx carcinoma, salivary tumor, and neoplasm in pharynx and oral cavity are analysed. The essential results of the investigation in regard to the characteristics sex, age, smoking, habitude, tumor in the family anamnesis, and occupational exposure are presented.

Adult↗
PubMed1988

Hemagglutinating and adherence properties of Staphylococcus saprophyticus: epidemiology and virulence in experimental urinary tract infection of rats.

We studied hemagglutinating and adherence properties in Staphylococcus saprophyticus isolates originating from symptomatic urinary tract infections. 12/13 (92%) of strains adhered to Hep cells and 11/13 (85%) were able to agglutinate sheep erythrocytes. Adherence properties differed markedly between strains (P less than 0.0001). Two strains, one hemagglutinating and adherent and one negative for both properties were chosen for experimental urinary tract infections. Results indicate that presence of the hemagglutinin favours colonization of kidney tissue.

Animals↗
PubMed1987

Characterisation of a type-I collagen trimeric cross-linked peptide from calf aorta and its cross-linked structure. Detection of pyridinoline by time-of-flight secondary ion-mass spectroscopy and evidence for a new cross-link.

A collagenous trimeric cross-linked peptide has been isolated from the insoluble matrix of calf aorta, using trypsin solubilisation, and purified by gel filtration, cation-exchange chromatography and reversed-phase HPLC. Molecular mass and amino acid composition indicated that the C-terminal, non-helical region of type I collagen in its dimer form, designated as [ColC(I)]2, is cross-linked to a tryptic peptide TN(I) from the N-terminal helical cross-link region of an adjacent type I molecule, forming the cross-linked peptide [ColC(I)]2 X TN(I). Amino acid sequence analysis of the peptide yielded a series of sequences corresponding to the cross-linking domains ColC(I) and TN(I) and furnished the first direct chemical evidence for the 4D staggered arrangement of type I molecules within native fibers. The trifunctional cross-linking amino acid pyridinoline was shown to occur in the peptide, confirming the peptides three-chain structure. Pyridinoline was isolated from the cross-linked peptide by preparative amino acid analysis and reversed-phase HPLC and identified by its ultraviolet absorption spectra, its fluorescence excitation and emission spectra and, for the first time, its time-of-flight secondary ion-mass spectrum. The high sensitivity of the latter method, exceeding that of fast-atom-bombardment mass spectroscopy by three orders of magnitude, allowed detection of pyridinoline in the picomole range. The occurrence of pyridinoline in non-stoichiometric amounts, the presence of hydroxylysine in hydrolysates of all cross-linked peptides and the finding that hydrolysates also contained an unidentified component indicated that there is at least one cross-link form that is different from pyridinoline and is hydrolysable.

Amino Acid Sequence↗
PubMed1986

Contribution of cloned virulence factors from uropathogenic Escherichia coli strains to nephropathogenicity in an experimental rat pyelonephritis model.

Escherichia coli 536 (O6:K15:H31), which was isolated from a case of urinary tract infection, determines high nephropathogenicity in a rat pyelonephritis system as measured by renal bacterial counts 7 days after infection. The loss of S fimbrial adhesin formation (Sfa-) (mannose-resistant hemagglutination [Mrh-] and fimbria production [Fim-]), serum resistance (Sre-), and hemolysin production (Hly-) in the mutant 536-21 led to a dramatic reduction of bacterial counts from almost 10(5) to only 40 cells per g of kidney. The reintroduction of the cloned S fimbrial adhesin determinant (sfa) increases the virulence of the avirulent mutant strain by a factor of 20; almost the same effect was observed after restoration of serum resistance by integration of an sfa+ recombinant cosmid into the chromosome. Additional reintroduction of the Hly+ phenotype by transformation of two hly determinants increased the virulence of the strains. Hemolysin production determined increased renal elimination of leukocytes and erythrocytes. Thus all three determinants investigated, S fimbriae, serum resistance, and hemolysin, contribute to the multifactorial phenomenon of E. coli nephropathogenicity.

Adhesins, Escherichia coli↗
PubMed1983

An Ehrlich chromogen in collagen cross-links.

A well-characterized three-chain peptide [(Col1)2 X T9] from human type III collagen was a rich source of Ehrlich chromogen. The corresponding two-chain peptide [(Col1)2] was not, implying that the Ehrlich chromogen is a trifunctional cross-link. (Col1)2 X T9 also contained pyridinoline, which is not an Ehrlich chromogen. The 7S domain of type IV collagen also contained an Ehrlich chromogen.

Amino Acids↗
PubMed1981

[Chemotherapy with fosfomycin, cefoxitin, and cefotaxime in experimental E. coli-pleuropneumonia (author's transl)].

Two models of pneumonia--the experimental E. coli-pleuropneumonia and "intrapulmonary" E. coli-pneumonia--were employed in these studies. Only fosfomycin was effective in both models even at the low dosage of 100 mg/kg/d. The comparative drugs cefotaxime and cefoxitin, however, were not able to reduce the bacteria in both lungs even at very high dosages of 900 mg/kg and 300 mg/kg per day respectively over 6 days.

Animals↗
PubMed1979

The covalent structure of calf skin type III collagen. I. The amino acid sequence of the amino terminal region of the alpha 1(III) chain (position 1--222).

The amino terminal 227 amino acid residues of the alpha 1(III) chain contain four CNBr peptides: alpha 1(III)CB3A (79 residues), CB3B, CB3C (6 residues each), CB7 (37 residues) and CB6 (99 residues). Fragmentation of the CNBr peptides was carried out using trypsin, chymotrypsin and the protease from Staphylococcus aureus V8. The fragments obtained were isolated by a combination of molecular sieve and ion exchange chromatography. The sequence analysis was performed according to the automated Edman degradation procedure.

Amino Acid Sequence↗