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C Jung

Publications and source records attributed to C Jung.

At least 127 records · Page 7Linked to original sources
PubMed1994

Membrane association of lipoprotein lipase and a cAMP-binding ectoprotein in rat adipocytes.

cAMP-binding ectoprotein (Gce1) and lipoprotein lipase (LPL) are anchored to plasma membranes of rat adipocytes by glycosylphosphatidylinositol (GPI) moieties as demonstrated by cleavage by bacterial phosphatidylinositol-specific phospholipase C (PI-PLC), reactivity with anti-crossreacting determinant antibodies (anti-CRD), and metabolic labeling with radiolabeled palmitic acid and myo-inositol. Quantitative release from the membrane of LPL and Gce1 requires both lipolytic removal of their GPI anchors and the presence of either 2 M NaCl or 1 mM inositol 1,2-cyclic monophosphate or inositol 1-monophosphate. PI-PLC-cleaved and released LPL or Gce1 reassociates with isolated plasma membranes of rat adipocytes and, less efficiently, with membranes of 3T3 fibroblasts. The specificity of the reassociation is demonstrated (i) by its inhibition after pretreatment of the membranes with trypsin, (ii) by its competition with inositol 1,2-cyclic monophosphate and inositol 1-monophosphate in a concentration-dependent manner, and (iii) by the limited number of binding sites. Enzymic or chemical removal as well as masking with anti-CRD antibodies of the terminal inositol (cyclic) monophosphate moiety of hydrophilic Gce1 and LPL significantly impairs the reassociation. These data suggest that in rat adipocytes GPI-proteins are not readily released from the cell surface upon lipolytic cleavage, but remain associated through a receptor which specifically recognizes the terminal inositol (cyclic) monophosphate epitope of the (G)PI-PLC-cleaved GPI moiety. This interaction may have implications for the regulated membrane release of GPI-proteins and for their possible internalization.

3T3 Cells↗
PubMed1994

The carbon monoxide stretching modes in camphor-bound cytochrome P-450cam. The effect of solvent conditions, temperature, and pressure.

The effect of pH, monovalent cations, glycerol, temperature, and pressure on the carbonmonoxy (CO) stretching mode of camphor-bound cytochrome P-450cam (CYP 101) was studied. Two effects, band overlap and frequency shift, have been observed. The CO stretch infrared band located at about 1940 cm-1 is asymmetric because of the overlap of three bands at about 1931 cm-1, 1939 cm-1, and 1942 cm-1 with strongly different populations. Reducing the temperature or increasing the pressure leads to splitting the band or switching the asymmetry from the lower energy side to the higher energy side of the infrared band. The overlap of several CO stretch bands indicates conformational substates within the heme pocket. A frequency shift of the predominantly populated band is observed by changing all the parameters mentioned. The pH-induced frequency shift follows an S-shape with the pK at 6.2, which matches the pK observed for the pH-induced high-spin/low-spin transition. Conformational changes on the proximal heme side are suggested to be the origin. Monovalent cations at saturating concentration induce a small frequency shift depending on the ion radius. The potassium ion is the one that induces a CO stretch frequency with the highest wave-number while sodium and lithium (smaller radii) and rubidium and caesium ion (larger radii) have diminished values, which is supporting evidence for the special function of the potassium ion within the structure. Glycerol and hydrostatic pressure induce a red shift of the CO stretching frequency. Forced contact of the polar hydroxyl group of Thr252 of the I helix induced by pressure and indirectly by glycerol is suggested to change the CO dipole moment, reflecting in the decreased CO stretching frequency.

Camphor↗
PubMed1994

The proton activity at cryogenic temperatures--a possible influence on the spin state of the heme iron of cytochrome P-450cam in supercooled buffered solutions.

The electronic absorption spectra for camphor-bound cytochrome P-450cam have been analysed in the temperature range between 78 K and 298 K. The well-known high-spin/low-spin equilibrium has been detected between 298 K and 220 K. Depending on the cooling rate, below 220 K a new species was found in the absorption spectra. In contrast, the electronic absorption spectra for camphor-free cytochrome P-450cam between 78 K and 295 K show no significant spectral changes. The conversion between the spin states of camphor-bound cytochrome P-450cam and the appearance of the new species do not correspond to the temperature-induced change in the paH value of the aqueous glycerol mixture containing phosphate or cacodylate buffer (paH 7.0). For this study a spectroscopic procedure for the determination of the temperature dependence of the paH value of the solvent for the range 78-295 K is presented using dyes as pH-indicators. It is shown that the state of the acid-base equilibrium frozen in is strongly dependent on the cooling rate of the mixture.

Buffers↗
PubMed1994

Two brothers with characteristic facial appearance, severe psychomotor retardation, hypospadias, contractures, and other symptoms: a new recessive syndrome?

We report on two severely mentally retarded male children of consanguineous parents who seem to be affected by an identical syndrome. The main physical anomalies are typical facial stigmata with a broad nasal bridge, a bulbous nose, upward slanting palpebral fissures, microretrognathia, low hair line, and large ears with an incompletely developed upper helix. In addition, both brothers had hypospadias type II, limb contractures, and delayed bone age. One child had a bilateral cleft lip with cleft palate and cryptorchidism, and developed scoliosis during adolescence. The other had bilateral inguinal hernias and strabismus. Chromosome analysis showed a normal karyotype in both. The striking similarity between the brothers, the dissimilarity to other known syndromes, and the parental consanguinity argue in favour of a new, hitherto undescribed, possibly autosomal recessive syndrome.

Abnormalities, Multiple↗
PubMed1994

Presymptomatic diagnosis in families with adenomatous polyposis using highly polymorphic dinucleotide CA repeat markers flanking the APC gene.

A panel of five multiallelic and highly informative dinucleotide CA repeat markers flanking the APC gene was used for presymptomatic diagnosis of familial adenomatous polyposis coli (FAP). Marker regions were amplified by PCR. DNA fragments were separated by electrophoresis in denaturing polyacrylamide gels and visualised by ethidium bromide staining. Two or more markers were found to be informative in all nine families tested, and all 23 persons at risk could be diagnosed as affected or unaffected by the disease gene, the probability being > 99.9% in 14 cases from six families in which flanking markers were informative. We found no indication for locus heterogeneity of the disease in our sample. The polyposis phenotype and its extracolonic manifestations co-segregated with a distinct haplotype determined by the markers flanking the APC gene. In one family with no remaining living affected members, we could infer the high risk haplotype from genotyping of first degree relatives. The segregation of this haplotype is consistent with the occurrence of CHRPEs in the progeny. In a sporadic case we made use of the typical early extracolonic manifestations of the disease (osteomas, desmoids) to identify the high risk haplotype. We conclude from our experience that indirect genotyping of FAP with this particular panel of closely linked and highly polymorphic microsatellite markers is a rapid, efficient, and highly reliable method for presymptomatic diagnosis of FAP.

Adenomatous Polyposis Coli↗
PubMed1993

Apocytochrome P450cam is a native protein with some intermediate-like properties.

Holo- and apocytochrome P450cam were studied by differential scanning calorimetry (DSC), limited proteolysis, second-derivative spectroscopy, circular dichroism, and size-exclusion chromatography. The holoprotein shows three folding units (domains) in DSC. The prosthetic group is related to the most unstable domain, which has a thermal transition at 41.9 degrees C. Compared with the holoprotein, apocytochrome P450cam has a reduced helix content. The protein is compact as judged by the Stokes radius and is still able to undergo a two-state transition. However, the enthalpy change at thermal melting is reduced from 980 kJ/mol for the holoprotein to 135 kJ/mol for the apo form. Parts of the molecule have a destabilized tertiary structure. This is indicated by second-derivative spectroscopy, circular dichroism in the near-ultraviolet region, and a high susceptibility to proteolytic digestion. Apocytochrome P450cam is considered a native protein with the extremely low stability of delta G = 7.5 kJ/mol, thus showing at the same time intermediate-like properties. The importance of the properties for in vivo folding are discussed.

Apoenzymes↗
PubMed1993

Substrate induced changes of the active site electronic states in reduced cytochrome P450cam and the photolysis product of its CO complex. Low-temperature magnetic circular dichroism data.

MCD spectra of camphor-free and camphor-bound reduced cytochrome P450cam have been recorded for the near UV and visible spectral regions at temperatures from 300K down to 2.1K and compared with those of the carbon monoxide photoproducts generated at 4.2K. In the absence of camphor, the reduced P450 is spectroscopically different from the photoproduct. In the presence of camphor, however, the spectra of the reduced P450 and of the photoproduct are almost similar and behave like the photoproduct of the camphor-free enzyme. This behavior indicates that substrate binding induces a higher active site rigidity. From the significant alteration of the temperature dependence of the MCD intensity for the reduced enzyme induced by camphor binding it is concluded that the near degeneracy of the electronic ground state in the substrate-free enzyme is removed by substrate binding.

Camphor↗
PubMed1993

Construction of a barley (Hordeum vulgare L.) YAC library and isolation of a Hor1-specific clone.

We have constructed an EcoRI-based YAC (yeast artificial chromosome) library from barley (Hordeum vulgare L. cv. Franka) using the vector pYAC4. The library consists of approximately 18,000 recombinant YACs with insert sizes ranging between 100 and 1000 kb (average of 160 kb) corresponding to 50% of the barley genome. Size fractionation after ligation resulted in an increased average insert size (av. 370 kb) but also in a substantial decrease in cloning efficiency. Less than 1% of the colonies showed homology to a plastome-specific probe; approximately 50% of the colonies displayed a signal with a dispersed, highly repetitive barley-specific probe. Using a primer combination deduced from the sequence of a member of the small Hor1 gene family coding for the C-hordein storage proteins, the library was screened by polymerase chain reaction and subsequently by the colony hybridization technique. A single YAC, designated Y66C11, with a 120 kb insert was isolated. This DNA fragment represents a coherent stretch from the terminal part of the Hor1 gene region as judged from the correspondence of the restriction patterns between Y66C11 DNA and barley DNA after hybridization with the Hor1-specific probe. Restriction with the isoschizomeric enzymes HpaII/MspI suggests a high degree of methylation of the Hor1 region in mesophyll cells but not in YAC-derived (yeast) DNA.

Base Sequence↗
PubMed1992

Substrate analogue induced changes of the CO-stretching mode in the cytochrome P450cam-carbon monoxide complex.

The CO-stretching mode of the carbon monoxide ligand in reduced cytochrome P450cam, in the absence or presence of camphor and in the presence of nine different camphor analogues, was measured at room temperature using Fourier transform infrared spectroscopy. Substrate-free cytochrome P450cam--CO reveals a broad, slightly structured band resulting from an overlap of several stretching mode signals. The multitude of the signals indicates that cytochrome P450 exists in a dynamic equilibrium of several conformational substates. Binding of camphor or camphor analogues strongly influences this equilibrium. For substrate analogues which are not able to form a hydrogen bond to the hydroxyl group of tyrosine 96, the CO-stretching band is rather broad and asymmetric. In contrast, substrate analogues with one quinone group which form a hydrogen bond to the Tyr96 OH induce a shift and a sharpening of the CO-stretching mode band. For substrate analogues with two hetero groups, the infrared spectrum is slightly asymmetric or a minor band appears. Sterical hindrance, substrate mobility, and protein flexibility finally determine the position and width of the CO-stretching mode signals.

Camphor↗
PubMed1992

Multichannel circular dichroism investigations of the structural stability of bacterial cytochrome P-450.

The thermal unfolding of cytochrome P-450 LIN and P-450 CAM measured in presence and absence of their specific substrates was analyzed by circular dichroism (CD) and the alpha-helix content was estimated. Both proteins show, independent of the presence or absence of the substrates, nearly the same amount of loss of the CD in the peptide region. The comparison of the half transition temperatures determined from different chromophores and different methods indicates a non-two-state transition of the thermal unfolding. For such analysis we developed a new spectrometer, which is capable of measuring the CD simultaneously at all wavelengths in a limited wavelength region.

Camphor 5-Monooxygenase↗
PubMed1992

A DNA library from an individual Beta patellaris chromosome conferring nematode resistance obtained by microdissection of meiotic metaphase chromosomes.

We have used a standard protocol established for human chromosomes to create a chromosome-specific plasmid library from a Beta patellaris chromosome conferring nematode resistance. A monosomic addition line was chosen carrying 18 sugar-beet (Beta vulgaris L.) and one wild-beet (B. patellaris) chromosome. The wild-beet chromosome can readily be identified as a univalent during metaphase I of meiosis. Highly synchronized meiotic material was used to excise the univalents from four pollen mother cells. The chromatin was lysed in a 1 nl collection drop, the DNA purified and restricted with Rsa I, ligated into a vector containing universal sequencing primers, and amplified by the polymerase chain reaction. The amplified DNA was inserted into a standard plasmid vector and cloned. Approximately 23,000 recombinant plasmids were obtained of which 15,800 could be utilized. Their insert sizes ranged from 80 to 700 bp with an average of 130 bp. 61 clones were tested in more detail by genomic Southern hybridization with sugar-beet and wild-beet DNA. Of these 32 plasmids (52%) contained single-copy inserts, 11 (18%) were specific for wild-beet DNA indicating that the DNA cloned originates in the univalent chromosome. The application of this technique for establishing high-density RFLP maps for discrete regions of plant genomes is discussed.

Animals↗
PubMed1992

DNA markers closely linked to nematode resistance genes in sugar beet (Beta vulgaris L.) mapped using chromosome additions and translocations originating from wild beets of the Procumbentes section.

Genes conferring resistance to the beet cyst nematode (Heterodera schachtii Schm.) have been transferred to sugar beet (Beta vulgaris L.) from three wild species of the Procumbentes section using monosomic addition and translocation lines, because no meiotic recombination occurs between chromosomes of cultured and wild species. In the course of a project to isolate the nematode resistance genes by strategies of reverse genetics, probes were cloned from DNA of a fragmented B. procumbens chromosome carrying a resistance gene, which had been isolated by pulsed-field gel electrophoresis. One probe (pRK643) hybridized with a short dispersed repetitive DNA element, which was found only in wild beets, and thus may be used as a molecular marker for nematode resistance to progeneis of monosomic addition lines segregating resistant and susceptible individuals. Additional probes for the resistance gene region were obtained with a polymerase chain reaction (PCR)-based strategy using repetitive primers to amplify DNA located between repetitive elements. One of these probes established the existence of at least six different chromosomes from wild beet species, each conferring resistance independently of the others. A strict correlation between the length of the wild beet chromatin introduced in fragment addition and translocation lines and the repeat copy number has been used physically to map the region conferring resistance to a chromosome segment of 0.5-3 Mb.

Animals↗
PubMed1992

An N-proximal sequence of the alfalfa mosaic virus movement protein is necessary for association with cell walls in transgenic plants.

We have made transgenic tobacco plants (Nicotiana tabacum, cv. Xanthi nc) expressing the movement protein (P3, 300 amino acids) of alfalfa mosaic virus (A1MV) and two N-terminally deleted proteins lacking respectively 12 and 77 amino acids of the P3 sequence (P3 delta[1-12] and P3 delta[1-77]). The same proteins were expressed in recombinant yeast. By subcellular fractionation, the full-length P3 protein expressed by transgenic plants was found to be associated with cell walls as well as with cytoplasmic particulate material, as was the wild type movement protein expressed by A1MV-infected tobacco plants. P3 delta[1-12] behaved similarly but P3 delta[1-77] was found only in the cytoplasm. It thus appears that a polypeptide domain located between amino acids 13 and 77 of the P3 sequence is necessary for association of the protein with cell walls.

Cloning, Molecular↗
PubMed1991

Binding sites of pyridine in cytochrome P-450cam.

Careful titration of oxidized cytochrome P-450cam from Pseudomonas putida with pyridine revealed deviations of the Eadie plot from linearity in the substrate-bound as well as in the substrate-free protein. A binding model which assumes two binding sites for pyridine--the iron and the camphor binding site--is able to describe completely the nonlinear Eadie plot.

Binding Sites↗
PubMed1991

The high-spin/low-spin equilibrium in cytochrome P-450--a new method for determination of the high-spin content.

A new method for determination of the population of the high-spin state (high-spin content) in ferric cytochrome P-450 is presented. Based on curve fitting the electronic absorption spectra with a linear combination of gaussian bands analytical functions for the pure high-spin and pure low-spin states were constructed. These functions were used to fit the high-spin/low-spin mixed spectra. A good fit of the absorption spectra of six different cytochrome P-450 proteins in the presence and absence of substrates was found, indicating a similar pi-electron structure of the porphyrin and a similar chemical nature of the nearest coordination sphere of the iron in all cytochrome P-450 proteins.

Animals↗
PubMed1991

Expression of intercellular adhesion molecule-1 (ICAM-1) in the skin of patients with systemic scleroderma.

The expression and tissue distribution of intercellular adhesion molecule-1 (ICAM-1) in skin biopsies from 12 patients with systemic (SSc) and localized (LS) scleroderma was studied and compared to the biopsies from patients with lupus erythematosus (LE) and normal individuals. In normal human skin ICAM-1 expression was restricted to the vascular endothelium, infiltrating mononuclear cells (MNC), and to few individual keratinocytes. In the inflammatory stage of SSc, however, the expression of ICAM-1 was dramatically increased at the site of MNC infiltrates and could also be detected on fibroblast-like cells lying well apart from these infiltrates in the deep dermis. In contrast, in LS ICAM-1 was expressed mainly at the sites of MNC infiltrates. In LE ICAM-1 expression was confined to the keratinocytes, endothelial cells, and mononuclear cells in the upper parts of the dermis. Analysis of serial tissue sections from patients with SSc demonstrated also colocalization of staining of ICAM-1 around blood vessels with LFA-1-positive lymphocytes. Increased expression of ICAM-1 in the dermis of patients with SSc may represent an important mechanism by which MNC become localized and retained at a site of connective tissue inflammation, leading to the activation of fibroblasts.

Adult↗
PubMed1991

[The 32P-test in the diagnosis of intraocular melanoma--an obsolete study method?].

Results of the 32P uptake test for the diagnosis of choroidal melanoma in 41 patients are reported. The sensitivity was 80%, the specificity 86%, if a count rate ratio of more than 1.4 between tumor and normal tissue was considered as pathological. Ratios between 1.4 and 1.6 ought to be considered as equivocal in which case specificity increases to 90%. The 32P uptake test still remains a method of clinical relevance in the diagnosis of choroidal melanoma.

Choroid Neoplasms↗