Ribonucleotide reductase in melanoma tissue. EPR detection in human amelanotic melanoma and quenching of the tyrosine radical by 4-hydroxyanisole.

The characteristic EPR doublet of tyrosine radicals of the growth-regulating enzyme ribonucleotide reductase was detected in human melanoma tissue grown in nude mice. This was possible through the use of an amelanotic melanoma that does not exhibit disturbing EPR signals from melanin. The content of tyrosine radicals is higher in young tumor tissues than in older ones.

Binding of one-chain tissue-type plasminogen activator to fibrin, partially plasmin-degraded fibrin, lysine and heparin.

Tissue-type plasminogen activator (t-PA) binds to heparin with an association constant of 2.4 x 10(4) l/mol at pH 7.4.

Production and characterization of monoclonal antibodies against carcinoembryonic antigen (CEA).

In the experiments presented here 22 monoclonal antibodies (MoAbs) were produced which reacted with the tumor marker carcinoembryonic antigen (CEA). Eleven of the MoAbs reacted neither with peripheral blood granulocytes nor with purified spleen NCA-60 kDa and were therefore regarded as "CEA-specific". Only three antibodies of this group reacted exclusively with CEA-180 kDa.

The 5'-untranslated region of p23 mRNA from the Ehrlich ascites tumor is involved in translation control of the growth related protein p23.

The growth-related protein p23 of the Ehrlich ascites tumor (EAT) is preferentially expressed in the exponentially growing tumor; its synthesis is translationally controlled. p23 mRNA is efficiently translated in the wheat germ cell-free lysate. In contrast, p23 mRNA present in poly(A)+RNA isolated from EAT is not translated in cell-free systems of EAT and reticulocytes.

Patterns of cytokeratins and lamins in rat liver and in rat liver cell lines as shown by immunoblotting using the monoclonal antibodies A 45-B/B3 and A 51-B/H4.

The cytokeratins and lamins of rat liver nuclei, nuclear lamina, and cytoskeleton preparations as well as of rat liver cell lines were studied by immunoblotting using the monoclonal broad-range cytokeratin antibodies A 45-B/B3 and A 51-B/H4. A 45-B/B3 is bound to 64-, 58-, 55-, 52.5-, 49-, 45-, 43-, 39-, and 35-kDa proteins, which are already known as rat liver cytokeratins, excepted the 64- and 35-kDa bands.

Immunoaffinity purification of human alpha-fetoprotein (AFP) using monoclonal antibodies.

A two-step immunoaffinity isolation procedure for human alpha-fetoprotein (AFP) was developed resulting in highly purified AFP at high yield. A monoclonal antibody immunoadsorbent was used in the first step. Elution of AFP was carried out at alkaline pH by a solution of 0.

Interaction of progesterone derivatives with the digitalis target enzyme: impact of glycosidation on inhibitory potency.

As a function of the structural modification of the steroid nucleus, the inhibitory interaction of 11 progesterone derivatives with human Na/K-ATPase (Na+/K(+)-transporting ATPase, EC 3.6.1.

Second generation biosensors.

Enzyme-membrane electrodes using glucose oxidase in combination with peroxide detection dominate in the field of laboratory analyzers for diluted samples. Using the same indication principle, extremely fast responding glucose sensors have been fabricated by covering thin metal electrodes with a porous enzyme layer. In the second generation auxiliary enzymes and/or co-reactants are coimmobilized with the analyte converting enzyme in order to improve the analytical quality and to simplify the performance.

Exact computation of pattern probabilities in random sequences generated by Markov chains.

Observed patterns in macromolecular sequences are often considered as words and compared with their probabilities of occurring in random sequences. Calculation of these probabilities, however, often lacks rigour. We have developed an algorithm for exact computation of such probabilities for stochastic sequences that follow a Markov chain model.

Sequence similarities between tryptophan synthase beta subunit and other pyridoxal-phosphate-dependent enzymes.

On the basis of 8 tryptophan synthase beta subunits (EC 4.2.1.

Generation of lymphokine-activated killer cells in long-term cultures.

The induction of lymphokine-activated killer (LAK) cells with low levels of interleukin-2 (IL-2) was studied in long-term cultures with regard to the relationship between cytotoxicity and proliferation. Proliferation of LAK cells reduced their cytolytic activity, which was restored when proliferation stagnated. In order to explain this phenomenon, a competition between receptors of intermediate and high affinity for IL-2 is suggested.

Structural principles of B-DNA grooves hydration in fibers as revealed by Monte Carlo simulations and X-ray diffraction.

Being interested in possible effects of sequence-dependent hydration of B-DNA with mixed sequence in fibers, we performed a series of Monte Carlo calculations of hydration of polydeoxyribonucleotides in B form, considering all sequences with dinucleotide repeat. The computational results allow the ten base-stacking types to be classified in accordance with their primary hydration in the minor groove. As a rule, the minor groove is occupied by two water molecules per base pair in the depth of the groove, which are located nearly midway between the planes of successive base pairs and symmetrically according to the dyad there.

Immortalization and transformation of human fibroblasts by regulated expression of polyoma virus T antigens.

We have established conditions for the immortalization of human fibroblasts by the large T antigen of the rodent virus polyoma. This allows the mechanism of immortalization to be studied, without interference by transformation events, in cells with relatively stable chromosomes. Large T antigen could immortalize human fibroblasts if expression was driven by a heterologous promoter like the immediate early promoter/enhancer of cytomegalovirus or the inducible mouse mammary tumour virus (MMTV) promoter.

Recognition of different nucleotide-binding sites in primary structures using a property-pattern approach.

Consensus sequence patterns for beta-alpha-beta folds binding FAD, NAD and GTP were constructed on the basis of 11 steric and physicochemical properties. These property patterns permit detection and distinction of the respective nucleotide-binding sites on the basis of amino acid sequence analysis alone. The SWISS-PROT database (release 9) was screened with the three calculated patterns, and nucleotide-binding sites identified are presented.

Additional DNA long-range folding is an early process during stimulation of human lymphocytes.

There is disagreement about the existence of permanent single-strand breaks in the nuclear DNA of quiescent lymphocytes, possibly due to different experimental approaches. Using the nucleoid sedimentation technique, no evidence is found for spontaneous DNA single-strand breakage in unstimulated human lymphocytes and for quick break-sealing after mitogenic stimulation. An increased sedimentation rate of nucleoids, which can be monitored as soon as 3 h after stimulation, is shown to be due rather to an additional long-range folding of nuclear DNA.

Biological activities of synthetic peptides of the sequence of human interferon-alpha.

Theoretical and experimental data were obtained indicating a possible role of the amino acid sequence 69-80 of HuIFN-alpha for antiviral activity of interferon. In this paper, synthetic peptides (penta-, octa- and dodecapeptides), representing the sequence region of positions 69-80 of the primary structure of HuIFN-alpha-2 were investigated with regard to their ability to inhibit the cytopathic effect of VSV on MDBK cells and on embryonic human fibroblasts. The peptides themselves exhibit only a very weak antiviral activity; however, it was found that these peptides even increase the antiviral activity of HuIFN-alpha-2.

Inhibition of urokinase activity and prevention of urokinase receptor binding by monoclonal antibodies.

Two murine monoclonal antibodies produced against human urokinase-type plasminogen activator were characterized with respect to their antigen-binding specificity and their effects on urokinase activity and urokinase receptor binding. One of the antibodies binds to the protease domain of urokinase (Kass = 2.1 X 10(7) M-1).

Flow sorting of hybrid hybridomas using the DNA stain Hoechst 33342.

A two-step sorting procedure with the fluorescence-activated cell sorter (FACS) is described for the selection of hybrid hybridomas producing bispecific monoclonal antibodies. Parental hybridoma cells were first labelled before fusion with fluorescein isothiocyanate (FITC) and tetramethyl rhodamine isothiocyanate (TRITC); heterofluorescent cells were recovered after fusion. After a period of growth in culture, the cells were then stained with the DNA-specific dye bis-benzimidazole Hoechst 33342 and sorted on the basis of their DNA content.

High-sensitivity protein detection by a new "contact-copy" method using a protein A-neomycin phosphotransferase II fusion protein.

A new system for high-sensitivity protein detection by an immunoenzymatic "contact-copy" procedure is described. It is based on two components: (i) a microbiologically produced bifunctional fusion protein of protein A and neomycin phosphotransferase II (protein A-NPT II) in which the protein A moiety acts as a second immunological reagent while NPT II catalyzes the detection reaction and (ii) a novel kanamycin-loaded substrate matrix (kanamycin-cyanuric chloride-activated and sulfanilic acid-derivatized paper) brought into direct contact with a protein-carrying matrix after blot or dot application and initial immunoreaction--the NPT II enzyme reaction with [gamma-32P]ATP as cosubstrate leads to phosphorylation of the substrate kanamycin on the substrate matrix, which is used for further analysis. The contact-copy method has at least the same detection sensitivity as procedures employing 125I-protein A, but allows extremely short exposure times and avoids probe prelabeling.

Immunoelectron microscopic studies on the location of ribosomal proteins on the surface of the 40S ribosomal subunit from rat liver.

Seven ribosomal proteins have been localized by means of immunoelectron microscopy on the surface of the 40S ribosomal subunit from rat liver using monospecific antibodies. The location of ribosomal proteins S13/16, S19, and S24 is described for the first time, and that of ribosomal proteins S2, S3, S3a, and S7, which has been published previously on the basis of experiments performed with less well characterized antibody preparations [Lutsch et al., Mol.

A Mr 43,000 epidermal growth factor-related protein purified from the urine of breast cancer patients.

A tumor-associated epidermal growth factor (EGF)-like activity was detected in the urine of breast cancer patients by means of an EGF radioreceptor assay and an anchorage-independent growth assay. The clonogenic growth factor activity of pooled void volume eluate fractions from a Bio-Gel P-30 column was completely neutralized by an anti-human epidermal growth factor antiserum but not by an anti-transforming growth factor alpha antiserum. This activity was determined in the urine of 71 breast cancer patients.

Transfection by DNA-nuclear protein HMG1 complexes: raising of efficiency and role of DNA topology.

We have developed a novel and efficient transfection method based on the introduction of foreign DNA into mammalian cells in form of complexes of vector DNA with the nuclear protein HMG1. In this study, it is shown that a stabilization of the complexes against dilution dissociation by addition of soluble CaCl2 or by excessive HMG1 enhances the transfection efficiency. Furthermore, there are no differences in the transfection abilities between the 3 topological DNA forms, viz.