Fibrinogen--proteolysis in acute myelogenous leukemia (AML)

Fibrinopeptides were measured as direct indices of thrombin, plasmin and elastase in plasma samples obtained from patients with AML. Peptide patterns observed were consistent with spontaneous or drug induced plasmin-specific fibrinogenolysis (AML FAB M 1/3), elastase mediated proteolysis (AML FAB M 3/4) or DIC (AML FAB 4/5). DIC was also observed in septic, agranulocytotic patients.     

Isolation and characterization of a family of alpha-D-galactosyl-containing glycopeptides from Ehrlich ascites tumor cells

A family of glycopeptides that contain nonreducing terminal alpha-D-galactosyl residues has been isolated from Pronase digests of delipidated Ehrlich ascites tumor cells. The glycopeptides, which comprise 17.2% of the total plasma membrane hexose, have an average molecular weight of 7500 and are precipitated by Griffonia simplicifolia B4 isolectin, wheat germ agglutinin, and Ricinus communis lectin. Exo- and endoglycosidase digestion, periodate oxidation, permethylation analysis, and lectin reactivity provided evidence for a tentative carbohydrate structure for the glycopeptide mixture. The glycopeptides possess tetraantennary branched structures containing a trimannosyl core N-glycosidically linked via an N,N'-diacetylchitobiosyl unit to an asparagine residue. Each branch contained repeating leads to 3)-beta-D-Galp-(1 leads to 4)-beta-D-GlcNAcp-(1 leads to units resulting in a keratan-like structure, terminated with alpha-D-Galp-(1 leads to 3)-[alpha-D-Galp-(1 leads to 6)]-beta-D-Galp-units. The variation in the molecular weight observed for the glycopeptide mixture can be attributed to the variable amounts of leads to 3)-beta-D-Galp-(1 leads to 4)-beta-D-GlcNAcp-(1 leads to units found in the branch chains.     

Molecular basis for modulated regulation of gene expression in the arginine regulon of Escherichia coli K-12.

We compare the nucleotide sequences of the regulatory regions of five genes or groups of genes of the arginine regulon of Escherichia coli K-12: argF, argI, argR, the bipolar argECBH operon and the carAB operon. All these regions harbour one or two copies of a conserved 18 bp sequence which appears to constitute the basic arginine operator sequence (ARG box). We discuss the influence of ARG box copy number, degree of dyad symmetry, base composition, and position relative to the cognate promoter site on the derepression-repression ratios of the genes of the regulon. A novel hypothesis, based on structural considerations, is also put forward to account for the absence ot attenuation control.     

Autocatalytic polysialylation of polysialyltransferase-1.

Polysialic acid (PSA) is a specific and highly regulated post-translational modification of the neural cell adhesion molecule NCAM. Synthesis of PSA depends on the activity of a single enzyme, the polysialyltransferase-1 (PST-1), recently cloned from three mammalian species. The present study was carried out to investigate the catalytic mechanism of PST-1. Using a newly developed in vitro assay system, we demonstrate autopolysialylation for PST-1. The synthesis of PSA chains, which involved N-glycosylation sites, occurred immediately after contact with the activated sugar donor CMP-Neu5Ac. In contrast to the polysialylation of NCAM, where terminal sialylation in either the alpha2,3 or alpha2,6 position is required, the autopolysialylation could be started in the asialo-PST-1 isolated from CHO cells of the Lec2 complementation group. Pre-formed PSA chains were not transferred to NCAM. Nevertheless, the autocatalytic step is likely to be a prerequisite for enzymatic activity, since agalacto-PST-1 isolated from Lec8 cells was functionally inactive. Our data describe a novel route of autocatalytic maturation of a glycosyltransferase and thereby provide a new basis for studies aimed at elucidating and influencing the catalytic functions of PST-1.     

Synthesis,characterization, and electrocatalytic behaviour of hydrothermally grown nanostructured La2O3 and La2O3/K-complex

Rare earth metals play a conspicuous role in magnetic resonance imaging (MRI) for detecting cancerous cells. The alkali metal potassium is a neurotransmitter in the sodium–potassium pump in biomedical sciences. This unique property of rare earth metals and potassium drew our attention to carry forward this study. Therefore, in this work, previously synthesized potassium (K) complexes formed by the reflux of 4-N,N-dimethylaminobenzoic acid (DBA) and potassium hydroxide in methanol, and named [(μ2–4-N,N-dimethylaminobenzoate-κO)(μ2–4-N,N-dimethylaminobenzoic acid-κO)(4-N,N-dimethylaminobenzoic acid-κO) potassium(I) coordination polymer)] were treated hydrothermally with La₂O₃ nanomaterials to obtain a nanohybrid La₂O₃/K-complex. After that, the K-complex was analyzed using single-crystal X-ray diffraction and ¹H and ¹³C NMR spectroscopy. In addition, the structural and morphological properties of the as-prepared nanostructured La₂O₃/K-complex were also characterized, which involved an investigation using X-ray diffraction (XRD)spectroscopy, Fourier transform infrared (FTIR) spectroscopy, atomic force spectroscopy (AFM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) analysis. After this, the electrochemical redox behaviour of the synthesized nanohybrid material was studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Therefore, the results from these studies revealed that the as-prepared material was a La₂O₃/K-complex that has a promising future role in sensing various analytes, as it showed effective electrocatalytic behaviour.     

Molecular cloning and functional expression of bacteriophage PK1E-encoded endoneuraminidase Endo NE

Homopolymeric α-2,8-linked sialic acid (PSA) has been found as a capsular component of sepsis- and meningitis-causing bacterial pathogens, and on eukaryotic cells as a post-translational modification of the neural cell adhesion molecule (NCAM). The polysaccharide is specifically recognized and degraded by a phage-encoded enzyme, the endo-N-acetylneuraminidase E (Endo NE). Endo NE therefore has become a valuable tool in the study of bacterial pathogenesis and eukaryotic morphogenesis. In this report we describe the molecular cloning of Endo NE and the expression of a functionally active recombinant enzyme. The cloned DNA sequence (2436 bp) encodes a polypeptide of 811 amino acids, which at the 5′ end contains a totally conserved neuraminidase motif. Expressed in Escherichia coli, the enzyme migrates as a single band of approximately 74 kDa in SDS-PAGE. A central domain of 669 amino acid residues is about 90% homologous to the recently cloned Endo NF. Both phage-induced lysis of bacteria and the catalysis of PSA degradation by the recombinant enzyme are efficiently inhibited by a polyclonal antiserum raised against the intact phage particle. The C-terminal region seems to be essential to enzymatic functions, as truncation of 32 amino acids outside the homology domain completely abolishes Endo NE activity. Our data also indicate that the 38 kDa protein, previously assumed to be a subunit of the Endo NE holoenzyme, is the product of a separate gene locus and is not necessary for in vitro depolymerase activity.