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B Fricke

Publications and source records attributed to B Fricke.

At least 37 records · Page 2Linked to original sources
PubMed1995

Unusual chromatographic behaviour and one-step purification of a novel membrane proteinase from Bacillus cereus.

Cell envelopes of Bacillus cereus contain a casein-cleaving membrane proteinase (CCMP) and an insulin-cleaving membrane proteinase (ICMP), which differ in their substrate and inhibitor specificity from all Bacillus proteinases described previously. They remained localized in the cytoplasmic membrane after treatment with lysozyme and mutanolysin and they are strongly attached to the membrane compared with other known membrane proteinases. Only high a concentration of the Zwitterionic detergent sulfobetain SB-12 enabled an effective solubilization of both membrane proteinases. The usual conventional purification methods, such as chromatofocusing, ion-exchange chromatography and hydrophobic interaction chromatography in the presence of detergent concentrations beyond their critical micelle concentration, could not be applied to the purification, because the solubilized membrane proteinases bound strongly and irreversibly to the chromatographic matrix. In the search for other purification methods, we used a tentacle ion-exchanger (EMD trimethylaminoethyl-Fractogel) to reduce the hydrophobic interactions between the proteinases and the matrix. All contaminating proteins could be removed by a first gradient of sodium chloride without elution of CCMP; a second gradient with isopropanol and a decreasing salt concentration resulted in an efficiently purified CCMP. The ICMP was irreversibly denaturated. Purified CCMP is a member of the metalloproteinase family with a pH optimum in the neutral range and a temperature optimum of 40 degrees C, whose properties differ from the serine-type membrane proteinase of Bacillus subtilis described by Shimizu et al. [Agric. Biol. Chem., 47 (1983) 1775]. It consists of two subunits in sodiumdodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions (Mr 53,000 and 65,000); however, the molecular mass of the purified enzyme could not be determined by size exclusion or SDS-PAGE, because the purified enzyme aggregated at the top of the gel matrix. CCMP solubilized before the purification process, could be eluted in the presence of 0.1% octylphenol-poly(ethyleneglycol ether)9-10 (Triton X-100) in two peaks of Mr 56,000 and 128,000, respectively. We discuss this special chromatographic behaviour of the CCMP from Bacillus cereus, with regard to the strong hydrophobic interactions of the enzyme with the chromatographic matrix and additional self-aggregation, which could only be dissolved by solvents such as isopropanol.

Bacillus cereus↗
PubMed1995

A periplasmic insulin-cleaving proteinase (ICP) from Acinetobacter calcoaceticus sharing properties with protease III from Escherichia coli and IDE from eucaryotes.

A periplasmic insulin-cleaving proteinase (ICP), purified to its electrophoretic homogeneity in the SDS-PAGE from the Gram-negative bacterium Acinetobacter calcoaceticus, was examined and compared in its properties with the protease III (protease Pi, pitrilysin, EC 3.4.99.44) of Escherichia coli and the insulin-destroying proteinase (IDE, insulinase, EC 3.4.99.45) from eucaryotes. The enzyme was proven to be a metalloprotease like protease III and IDE, as was shown by the inhibitory effects exerted by EDTA and o-phenanthroline. Furthermore, dialysis against EDTA and o-phenanthroline led to a complete loss of activity, which could be restored by addition of Co2+, and, to a lesser extent, but at a lower metal ion concentration by Zn2+. Similar to protease III and IDE, ICP prefers the cleavage of small polypeptides (insulin, insulin B-chain, glucagon) to the cleavage of proteins (casein, human serum albumin, globin) and was inactive against synthetic amino acid derivates (esters, p-nitranilides, and furoylacroleyl substrates) of subtilisin, thermolysin, trypsin, and chymotrypsin. The peptide-bond-specificity of the ICP in the cleavage of the oxidized insulin B-chain was investigated and the results were compared to the specificity of protease III of E. coli, IDE, protease-24,11, and thermolysin. Cleavage sites in the oxidized insulin B-chain generated by ICP are Asn3-Gln4, His10-Leu11, Ala14-Leu15, Leu17-Val18, Gly23-Phe24, Phe24-Phe25, and Phe25-Tyr26. Principally, ICP cleaves between hydrophobic amino acids and amides. The ICP shares one of the only two cleavage sites with the protease III and four sites with the IDE.

Acinetobacter calcoaceticus↗
PubMed1995

Topography and distribution of nerve fibers in the posterior longitudinal ligament of the rat: an immunocytochemical and electron-microscopical study.

The distribution and immunocytochemical characterization of nerve fibers and their terminals in the posterior longitudinal ligament of the rat lumbar vertebral column was studied in whole-mount preparations and serial semithin and ultrathin sections. Differences in the localization, distribution pattern and density of peptidergic and catecholaminergic nerve fibers were found in the vertebral and intervertebral regions of the posterior longitudinal ligament. For immunocytochemistry, free floating specimens were incubated with primary antibodies against protein gene product 9.5, substance P, calcitonin gene-related peptide, dopamine-beta-hydroxylase, vasoactive intestinal polypeptide and neuropeptide Y together with the avidin-biotin-peroxidase method. In whole-mount preparations, the neural marker protein gene product 9.5 is immunostained in all unmyelinated nerve fibers in the posterior longitudinal ligament, thus giving a panoramic view of the nerve fiber plexus. The most striking nerve fiber plexus is localized in the intervertebral region. In this region, the posterior longitudinal ligament is rich in capillaries that form a dense plexus within its ventral part and extend to the outer layer of the annulus fibrosus. The peptidergic and catecholaminergic innervation of the posterior longitudinal ligament is discussed in the context of pain syndromes related to the vertebral column and degenerative lumbar spine diseases.

Animals↗
PubMed1993

Periplasmic aminopeptidases in Acinetobacter calcoaceticus and Pseudomonas aeruginosa.

The greater part of the intracellular aminopeptidases in Pseudomonas aeruginosa and Acinetobacter calcoaceticus is soluble. The localization of aminopeptidases in the cells was examined using the osmotic shock method with some modifications. When the cells of A. calcoaceticus and P. aeruginosa of the logarithmic phase were subjected to an osmotic shock, all aminopeptidases investigated were mainly localized in the sucrose supernatants and in the periplasm. Acid phosphatase as marker enzyme for periplasm showed a similar distribution between the fractions as the aminopeptidases. The periplasmic aminopeptidases of both microorganisms were separated by FPLC on Superose 12 and their molecular masses were determined. The results obtained show that at least four different aminopeptidases occur in the periplasm, a leucyl aminopeptidase (LAP, cleaving Leu-NH-NH2, 400 kDa), a glutamyl aminopeptidase (GAP, 200 kDa), an alanyl aminopeptidase (AAP, 80 kDa) and a prolyl aminopeptidase (PAP, 65 kDa). The results are in agreement for both species. Our results show clearly that aminopeptidases of these typical members of Gram-negative bacteria are mainly periplasmic like degrading enzymes (alkaline and acid phosphatases, 5'-nucleotidase, cyclic phosphodiesterase), detoxifying enzymes and binding proteins for amino acids and sugars.

Acinetobacter calcoaceticus↗
PubMed1993

Phase separation of nonionic detergents by salt addition and its application to membrane proteins.

By adding salts (sodium chloride, ammonium sulfate), it is possible to induce phase separation in membrane-protein solubilisates containing Triton X-100 or Nonidet P-40 at temperatures between 0 and 20 degrees C. Other nonionic detergents of the Brij, Lubrol, and Tween series can also be used for this procedure. The salt concentration required for induction of phase separation is dependent on the hydrophobicity of the detergent used. For detergents of the Triton series it seems that detergents with lower hydrophilic lipophilic balance numbers need lower salt concentrations to separate the phases than those with larger hydrophilic parts. Ammonium sulfate precipitation as an initial purification step for membrane proteins should be avoided in the presence of the nonionic detergents tested. Instead of this procedure, phase separation induced by sodium chloride or ammonium sulfate can be recommended, as was proved for membrane-bound proteases of Pseudomonas aeruginosa and Bacillus cereus and for bacteriorhodopsin.

Ammonium Sulfate↗
PubMed1993

Nasal airway, lip competence, and craniofacial morphology.

The aim of the present investigation was to demonstrate whether children selected by their open lip posture show differences in their nasal airway resistance and facial morphology compared to children with closed lip closure. Thirty-two children with poor lip competence were compared to a control group of 20 with secure mouth closure. Patients with poor lip competence showed a significantly higher ML-NSL angle and also ML-NL angle. Anterior rhinomanometry, as well as measurements of the pharyngeal space on lateral headfilms, displayed no significant differences between the two groups. The same material was also grouped cephalometrically into skeletal open and skeletal deep bite configurations. The mean value of the nasal airway passage was lower in the skeletal open group, but not at a significant level.

Airway Resistance↗
PubMed1992

Purification of a periplasmic insulin-cleaving proteinase from Acinetobacter calcoaceticus.

Cells of Acinetobacter calcoaceticus contain a constitutive periplasmic metalloproteinase showing similar properties as the periplasmic metalloproteinase of Escherichia coli. The periplasmic proteinase of A. calcoaceticus was purified, starting from periplasm, by ammonium sulfate precipitation, hydrophobic interaction chromatography and chromatofocusing up to the homogeneity of the enzyme in SDS-electrophoresis with a yield of 6.7% and a purification factor of 417. The enzyme has a molecular mass of 108,000 (gel filtration) or 112,000 (native electrophoresis), and consists of four identical subunits with a molecular mass of 27,000 (SDS-electrophoresis). The purified enzyme degrades preferentially polypeptides such as glucagon and insulin. Larger proteins are accepted as substrates to a considerably lower extent. All tested synthetic substrates with trypsin, chymotrypsin, elastase and thermolysin specificity were not cleaved. Therefore, the described enzyme was designated "insulin-cleaving proteinase" (ICP).

Acinetobacter calcoaceticus↗
PubMed1992

[A comparative study of the possibility of reducing the dosage in lateral teleradiographs].

Thanks to their capability for post-processing of image data, the digital radiological techniques introduced from 1970 onwards permit dose reduction with no loss of clinical information. The aim of this study was to establish the extent of possible dose reduction in orthodontic lateral cephalography. For this purpose, lateral cephalograms of a head phantom taken with varying radiation doses (5 to 150 mAs, constant 70 kV) were evaluated. The evaluations of ten judges were compared statistically. Conventional lateral cephalograms showed a statistically proven superiority of a number of exposure parameters for the sagittal and vertical localisation of reference points. This correlated with the radiological density of the structures. In contrast to the conventional technique, the reference points in all images obtained by digital luminescence radiography showed no such tendency. Digital luminescence thus meets the clinical need to reduce radiation dose (to about 20% of the usual dose) while providing no less diagnostic information.

Cephalometry↗
PubMed1992

[Cyclosporin A in therapy of chronic uveitis].

48 patients with chronic severe uveitis of pressumed noninfectious origin resistent to corticosteroids have been treated with Cyclosporin A. All patients had an initial loading dose of 5 mg/kg/day followed by a dose reduction according to ocular inflammatory activity and tolerability and according the guidelines by BenEzra, Nussenblatt and Timonen. Most of the patients received additional corticosteroids in a low dose. 35 out of these 48 patients (13 suffering from intermediate uveitis, 11 from retinal vasculitis, 5 panuveitis, 4 "pressumed histoplasmosis" and 2 sympathetic ophthalmia) were treated for 1 year and observed after withdrawing of Sandimmun for at least 6 months. The majority of these patients have manifested a positive therapeutic response to Cyclosporine, in particular patients suffering from vasculitis, panuveitis and sympathetic ophthalmia. All 35 patients were treated before for a long time with steroids without success, 19 out of these 35 in addition with cytotoxic agents. The immunosuppressive effect of Cyclosporine was not permanent, frequently the inflammation relapsed on reduction of dosage or withdrawing of the drug. Guidelines for combined regimen (Cyclosporine and corticosteroids and vitrectomy) were given. Although a large variety of side effects were reported the compliance was good.

Administration, Oral↗
PubMed1991

[Comparative study of the accuracy of localizing cephalometric reference points in using digital and conventional imaging technique].

The purpose of this study was to present possible advantages of digital luminescence radiography for cephalometry. Conventional and digitalized lateral headfilms were compared and evaluated. The first impression of an improved simultaneous presentation of bony structures and soft tissue profile in digital x-rays was statistically verified. A significant difference in identification of several reference points was proven by means of the F-test. The superior results of the digital luminescence radiography were evaluated in comparison with xeroradiography and experimental postdigitalization of conventional x-rays.

Cephalometry↗