Partial purification and characterization of a Ca(2+)-dependent protein kinase from pea nuclei

Almost all the Ca(2+)-dependent protein kinase activity in nuclei purified from etiolated pea (Pisum sativum, L.) plumules is present in a single enzyme that can be extracted from chromatin by 0.3 molar NaCl. This protein kinase can be further purified 80,000-fold by salt fractionation and high performance liquid chromatography, after which it has a high specific activity of about 100 picomoles per minute per microgram in the presence of Ca2+ and reaches half-maximal activation at about 3 x 10(-7) molar free Ca2+, without calmodulin. It is a monomer with a molecular weight near 90,000. It can efficiently use histone III-S, ribosomal S6 protein, and casein as artificial substrates, but it phosphorylates phosvitin only weakly. Its Ca(2+)-dependent kinase activity is half-maximally inhibited by 0.1 millimolar chlorpromazine, by 35 nanomolar K-252a and by 7 nanomolar staurosporine. It is insensitive to sphingosine, an inhibitor of protein kinase C, and to basic polypeptides that block other Ca(2+)-dependent protein kinases. It is not stimulated by exogenous phospholipids or fatty acids. In intact isolated pea nuclei it preferentially phosphorylates several chromatin-associated proteins, with the most phosphorylated protein band being near the same molecular weight (43,000) as a nuclear protein substrate whose phosphorylation has been reported to be stimulated by phytochrome in a calcium-dependent fashion.

[Determination of coumarins in radix Angelicae Dahuricae before and after processing]

This paper reports the contents of coumarins in Radix Angelicae Dahuricae before and after processing. By CS-930 TLC scanner, the total contents have been determined to be 0.190%, 0.571%, 0.178% and 0.421% respectively.

Low frequency of ras activation in 2-acetylaminofluorene- and 3'-methyl-4-(dimethylamino)azobenzene-induced rat hepatocellular carcinomas

Activation of ras protooncogenes in 11 2-acetylaminofluorene (AAF)-induced hepatocellular carcinomas (HCCs) or liver cell lines and 9 3'-methyl-(dimethylamino)azobenzene (3'-Me-DAB)-induced HCCs in rats was examined using the NIH3T3 cell transfection assay and oligonucleotide hybridization analysis. Only one cell line established from a AAF-treated rat liver demonstrated transforming activity with a point mutation and ATTA transversion at the second position of H-ras codon 61. The rates of ras activation were thus very low for both AAF- and 3'-Me-DAB-induced rat HCCs, the results thus extending and confirming the findings indicating that ras activation in rat HCCs induced by various type of carcinogens is infrequent.

In vitro progression-associated c-H-ras activation in neoplastic hepatocyte lines established from SV40-T antigen gene-harboring transgenic mice

In order to investigate the molecular mechanisms of multistep hepatocarcinogenesis in SV40-T antigen gene-harboring transgenic mice, 9 hepatocellular carcinoma (HCC) lines and 10 "preneoplastic" hepatocyte lines were established from the animals and their biological and molecular changes during culture were investigated. Three of the 9 HCC lines showed progression during culture in terms of growth rate and growth capability in soft agar and in nude mice. This progression was associated with the appearance of activated c-H-ras oncogene. Including these 3 lines, H-ras activation was observed in a total of 7 of the 9 HCC lines (78%), whereas it was found only in 1 of 10 (10%) "preneoplastic" hepatocyte lines. These data thus indicate that H-ras activation may be an event occurring at a relatively late stage of hepatocarcinogenesis in this transgenic mouse system and that it may serve towards completion of the carcinogenic process together with the T-antigen.

Absence of inhibition by lipoprotein (a) inhibition of tPA induced thrombolysis in a patient's plasma milieu

The increase in Lp(a) is strongly correlated with premature coronary artery disease. The Apo(a) has striking homology to plasminogen. It was found in an in vitro purified system that Lp(a) competes with both plasminogen and tissue-type plasminogen activator (tPA) for fibrin binding sites, thus resulting in a decrease in fibrin-dependent plasminogen activation. In this study, plasma fibrinolysis was studied in a young patient who had a consistently high level of Lp(a) (198 mg/dl) and had suffered from cerebral thrombophlebitis 12 months previously. The patient had normal levels of plasma plasminogen and fibrinogen. The euglobulin lysis time before and after venous occlusion was not prolonged, and after the addition of tPA to the patient's plasma or whole blood, the clot lysis time was normal. The same result was obtained when the patient's plasma was depleted of Lp(a) before clotting. When the patient's plasma serpins were inhibited, plasminogen activation by tPA in the presence of several fibrin concentrations was normal, suggesting that the formation of the ternary complex tPA - plasminogen - fibrin was not inhibited by the presence of high levels of Lp(a). It is concluded that a consistently high level of Lp(a) in this patient did not inhibit tPA-dependent fibrinolysis, and the thrombotic episode was not therefore related to deficient thrombolysis.

The propeptide of beta-glucuronidase. Further evidence of its involvement in compartmentalization of beta-glucuronidase and sequence similarity with portions of the reactive site region of the serpin superfamily

A significant portion of murine hepatocyte beta-glucuronidase is maintained within the endoplasmic reticulum (ER) by complex formation with the esterase active site of the protein egasyn. The carboxyl-terminal propeptide of the precursor form of glucuronidase appears important in localization of glucuronidase to the ER since a naturally occurring mutation in it is associated with decreased levels of ER glucuronidase. A sequence similarity was noted between the carboxyl-terminal propeptide and portions of the conserved sequences of the reactive site region of members of the serpin (serine proteinase inhibitor) superfamily. Also, previous studies had shown that a synthetic peptide, corresponding to the propeptide region, was a specific and potent inhibitor of the esterase activity of purified egasyn. Taken together, these results suggest that (a) the egasyn-glucuronidase system may use a novel mechanism related to that of serine proteinases and their inhibitors in complex formation and in subsequent localization of glucuronidase within the ER and that (b) a possible function of ER glucuronidase is to modulate the esterase activity of egasyn.

Detection of activated c-H-ras oncogene in hepatocellular carcinomas developing in transgenic mice harboring albumin promoter-regulated simian virus 40 gene

Hepatocellular carcinomas (HCCs) developing in transgenic mice harboring an albumin promoter-regulated simian virus 40 (SV40) tumor antigen gene were analyzed for activating point mutations of the c-H-ras oncogene. Oligonucleotide hybridization studies utilizing enzymatically amplified DNA sequences of paraffin-embedded tumor tissues revealed that 10 out of 25 HCCs contained either an A-to-T or an A-to-G conversion at the second position of codon 61. Northern blot studies confirmed expression of SV40 gene mRNAs in the tumor tissues of both mutation-positive and mutation-negative HCCs. These findings in association with earlier results thus strongly suggest that mutational activation of cellular oncogene may play an important role in SV40-initiated multistage hepatocarcinogenesis in vivo.

Direct electrophoretic detection of the allelic state of single DNA molecules in human sperm by using the polymerase chain reaction

We have developed a procedure that allows the detection of polymerase chain reaction (PCR) products derived from a single target DNA molecule in a human sperm without using radioactive probes. With this method, three genetic loci present in a single sperm can be amplified simultaneously. The amplification procedure is specific as well as efficient and permits detection of the PCR product by ethidium bromide staining after polyacrylamide gel electrophoresis. When allele-specific PCR primers that differ in length are used, the size of the PCR products of different alleles also vary in length, allowing the allelic state at each locus to be determined electrophoretically. Studies on individual sperm by using this procedure should facilitate the measurement of genetic recombination in humans over small physical distances. The ability to directly analyze the allelic state of PCR products from one cell rapidly and simply will also be useful for the prenatal diagnosis of genetic disease, especially in the analysis of single blastomeres taken from in vitro fertilized eggs prior to implantation.

Biological characterization of major polypeptides on the surface of spotted fever group rickettsiae

There are two major polypeptides on the surface of spotted fever group rickettsiae that play important roles as immunogens and possibly relate to the pathogenicity of rickettsial diseases. Digestion with trypsin and staphylococcal V-8 protease shows that the 115-kDa protein of Rickettsia conorii is a trypsin-sensitive, surface-exposed protein. The 135-kDa protein is relatively trypsin resistant. Both proteins resist heat treatment up to 52 degrees C and maintain their antigenic reactivity with monoclonal antibodies when the intact rickettsiae are heated. When rickettsiae are dissolved in SDS-containing sample buffer, these polypeptides lose their antigenic reactivity with monoclonal antibodies after incubation at 45 degrees C for 10 min. Staphylococcal V-8 protease does not appear to affect these polypeptides under the current experimental conditions. Monoclonal antibody to the 115-kDa protein reduces rickettsial attachment. The 115-kDa polypeptide may play a role in rickettsial adhesion to the host cell surface.

Carbohydrate binding specificities of several poly-N-acetyllactosamine-binding lectins

The structural requirements for the interaction of the Asn-linked poly-N-acetyllactosamine-type oligosaccharide moieties of glycoproteins with various N-acetylglucosamine-binding lectins were investigated by means of affinity chromatography on immobilized lectin-Sepharose columns. High molecular weight glycopeptides containing poly-N-acetyllactosamine-type oligosaccharides obtained by Pronase digestion of human erythrocyte ghosts were treated with 0.1 M trifluoroacetic acid at 100 degrees C for 40 min and then several oligosaccharide fragments were purified with an amino-bonded silica column. Among these oligosaccharide fragments, trisaccharide Gal beta 1-4GlcNAc beta 1-6Galol bound to the wheat germ agglutinin (WGA)- and pokeweed mitogen (PWM)-Sepharose columns, and also showed affinity to the Datura stramonium agglutinin (DSA)-, Lycopersicon esculentum (tomato) agglutinin- and Solanum tuberosum (potato) agglutinin-Sepharose columns. Pentasaccharide Gal beta 1-4GlcNAc beta 1-3(Gal beta 1-4GlcNAc beta 1-6)Galol showed weaker affinity to the WGA- and PWM-Sepharose columns, compared to the trisaccharide. Trisaccharide GlcNAc beta 1-3(GlcNAc beta 1-6)Galol showed weak affinity to the WGA-Sepharose column and did not show any affinity to the other lectin-Sepharose columns. Hexasaccharide Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAcol bound only to the DSA-Sepharose column, indicating that only DSA does not require a GlcNAc beta(1-6)- linkage for interaction.

Structural requirements for the binding of oligosaccharides to immobilized lectin of Erythrina variegata (Linn) var. orientalis

The structural requirements for the interaction of asparagine-linked oligosaccharide moieties of glycoproteins with Erythrina variegata agglutinin (EVA) were investigated by means of affinity chromatography on an EVA-Sepharose column. Some of the branched poly-N-acetyllactosamine-type oligosaccharides obtained from human erythrocyte band 3 glycoprotein were found to show high affinity to EVA-Sepharose, whereas complex-type oligosaccharides were shown to have low affinity. Hybrid type, oligomannose-type and unbranched poly-N-acetyllactosamine-type oligosaccharides bound very little or not at all to EVA-Sepharose. To further study the carbohydrate-binding specificity of this lectin, we investigated the interaction of immobilized EVA and oligosaccharide fragments obtained through partial hydrolysis from branched poly-N-acetyllactosamine-type oligosaccharides. Branched poly-N-acetyllactosamine-type oligosaccharides were subjected to limited hydrolysis with 0.1% trifluoroacetic acid at 100 degrees C for 40 min and then separated on an amino-bonded silica column. One of pentasaccharides thus prepared strongly bound to the EVA-Sepharose column. Structural analysis of this pentasaccharide showed that the Gal beta 1-4GlcNAc beta 1-3(Gal beta 1-4GlcNAc beta 1-6)Gal sugar sequence, which is an I-antigen determinant, was essential for the high affinity binding of the oligosaccharides to the EVA-Sepharose column.

Kinetics and mechanism of methanol and formaldehyde interconversion and formaldehyde oxidation catalyzed by liver alcohol dehydrogenase

It has been shown that the hydrophobic interaction in the active-site plays a fundamental role in substrate binding. Proper molecular orientation is required for hydride transfer (Dalziel and Dickinson, 1967). For methanol, the binding is unfavored due to the lack of a hydrophobic chain. In the enzyme-coenzyme-substrate complex, the small methyl group of the substrate is not held in a fixed position, resulting in a low hydride transfer rate. The binding of NAD+ to the enzyme does not exhibit a significant effect on the binding of methanol, nor does methanol affect NAD+ binding. In the presence of LADH, methanol is oxidized by NAD+ to formaldehyde, while formaldehyde can be oxidized by NAD+ to formate ion or reduced by NADH to methanol. These reactions follow a rapid equilibrium random mechanism. Among these three reactions, the reduction of formaldehyde is the most rapid. The rate of formaldehyde oxidation is faster than the oxidation of methanol. Our study with these non-hydrophobic substrates provides an important bridge between the bioinorganic activation of zinc-bound water and the bioorganic oxidation of ethanol. Furthermore, it furnishes some insight into an enzymatic system that is so highly sensitive to small changes in substrate chain length that it can magnify the consequence of a modest change in substrate hydrophobicity.