Purification of the microsomal Ca2+-ATPase from rat liver

Summary The Ca²⁺-ATPase from rat liver microsomes has been solubilized in Triton X-100 and purified to homogeneity by ficollsucrose treatment, column chromatography with agarose-hexane adenosine 5-triphosphate Type 2, and high pressure liquid chromatography (HPLC). The purified enzyme obtained by this sequential procedure exhibited a 183-fold increase in specific activity. After ficoll-sucrose treatment, the activity of the Ca²⁺-ATPase was stable for at least two weeks when stored at –70°C. In SDS-polyacrylamide gels, several fractions from HPLC chromatography showed a single band at a position corresponding to a molecular weight of about 107 kDa. This value is consistent with the molecular weight of the phosphoenzyme intermediate of endoplasmic reticulum (ER) Ca²⁺-ATPase. Further characterization of the ER Ca²⁺-ATPase was performed by western immunoblots. Antiserum raised against the 100-kDa sarcoplasmic reticulum (SR) Ca²⁺-ATPase cross-reacted with the purified Ca²⁺-ATPase from rat liver ER membranes.     

轴浆转运在神经再生中的作用

夹伤坐骨神经阻断标记蛋白在轴浆中的快、慢转运。3天后转运再现。第14天的转运距离与对照相似,说明再生神经的转运动能基本恢复。用快、慢转运测出的14天平均再生速度分别为1.77±0.14与1.96±0.07mm/d,比对照神经的正常生长速度快6.3—7倍,提示再生需要更多的转运物质。进一步发现再生神经中某些标记蛋白(慢转运波W1)的转运速度为10.25±0.66mm/d,约比对照快1倍,因此这些标记蛋白可能包含适应再生需要而加速转运的结构和功能物质。     

大肠杆菌青霉素G酰化酶基因及其邻近区域的核苷酸全序列

Some of microorganisms have been known to possess penicillin G acylase activity. The E. coli derived penicillin G acylase (PGA) can catalyze the conversion of penicillin G into phenylacetic acid and 6-amino-penicillanic acid, the latter is used as the starting compound for the industrial formation of semi-synthetic penicillins. Apart from its industrial importance, the enzyme PGA displays a number of interesting properties. Catalytically active enzyme is localized in the periplasmic space of E. coli cells and composed of two dissimilar subunits. The two subunits are apparently produced from a precursor protein, via a processing pathway hitherto unique in its features for a prokaryotic enzyme. The studies on processing of the precursor and on the relationship between structure and function of the mature enzyme are important theoretically. Previously we cloned a 3.5 kb DNA fragment from a strain (E. coli AS 1.76), which displays PGA activity. In this paper, we report a nucleotide sequence of the 3.5 kb DNA fragment containing PGA gene. After insertion of the DNA fragment into EcoR I and Hind III sites in pWR 13, pPGA 20 had been obtained. We subcloned the Hind III and Bg1 II treated fragment of 1.6 kb in length from pPGA 20 into Hind III and BamH I sites of pWR 13 to get a pPGA 1.6, and Bg1 II and EcoR I treated fragment of 1.9 kb in length into BamH I and EcoR I sites of pWR 13 to get a pPGA 1.9. The linearized pPGA 1.9 which were digested with appropriate restriction enzymes were progressively shortened from both ends respectively by digestion with Bal 31 nuclease, followed by cleavage of shortened target DNA off vector DNA molecules with appropriate restriction enzymes. The series of the DNA fragments shortened from EcoR I end were then cloned into plasmid pWR 13 which had previously digested with Hind III and Sma I enzymes (Fig. 1). The DNA fragment cloned in pWR 13 were directly sequenced on the resulted plasmids by using primer I and primer II. Thus we have obtained the complete nucleotide sequence of the 3.5 kb DNA fragment. The 3.5 kb fragment contains an intact PGA gene which is 2.6 kb.(ABSTRACT TRUNCATED AT 400 WORDS)     

Nucleotide sequence and analysis of the N-terminal coding region of the Spodoptera-activeδ-endotoxin gene of Bacillus thuringiensis aizawai 7.29

The nucleotide sequence of a 2711bp DNA segment which contains the N-terminal coding sequence and the 5' flanking region of a crystal protein gene (bta) from Bacillus thuringiensis subsp. aizawai 7.29 has been determined. The coding region encodes an 824 amino-acid polypeptide corresponding to a carboxy-terminally truncated delta-endotoxin specifically active against the cotton leaf worm Spodoptera littoralis. Comparison of the deduced amino acid sequence of the bta gene with that of the 4.5, 5.3 and 6.6 kb classes of lepidopteran-active delta-endotoxins revealed that the Bta sequence contains a very high level of amino acid substitutions in the N-terminal part of the protoxin molecule. The substitutions are grouped in several highly variable segments separated by highly conserved regions. These conserved domains are also present in the dipteran- and coleopteran-active delta-endotoxins. The control region of the bta gene shows considerable DNA identity with the control regions of the other lepidopteran-active genes. Deletions of the 3' region of the gene were carried out and the toxic fraction of the bta delta-endotoxin was identified with the N-terminal half of the molecule.     

Monoclonal antibody AA4, which inhibits binding of IgE to high affinity receptors on rat basophilic leukemia cells, binds to novel alpha-galactosyl derivatives of ganglioside GD1b

Mouse monoclonal antibody AA4 inhibits the binding of IgE to high affinity IgE receptors on the rat basophilic leukemia cell line RBL-2H3. As shown by immunostaining of thin layer chromatograms, antibody AA4 binds avidly to two disialogangliosides (antigen I and antigen II) that occur in this cell line. The two antigens were purified by anion exchange chromatography followed by short-bed continuous thin-layer chromatography. About 230 micrograms of antigen I and 60 micrograms of antigen II were obtained from 20 g (wet weight) of leukemia cells. The structures of both purified antigens were determined to be alpha-galactosyl derivatives of the ganglioside GD1b by fast atom bombardment-mass spectrometry, by chemical ionization-mass spectrometry of permethylated samples, by gas chromatography-mass spectrometry of partially methylated alditol acetates, and by treatment with exoglycosidases and mild acid hydrolysis. The structure of antigen I is: (formula; see text) Antigen II has an additional alpha-galactosyl residue as follows: (formula; see text) The ceramide of antigen I contains approximately equal amounts of C24:0, C22:0, C20:0, C18:0, and C16:0 N-acyl fatty acids. The ceramide base is predominantly sphingosine along with a small amount of dihydrosphingosine. In contrast, the ceramide of antigen II contains mainly C24:0 N-acyl fatty acid with much lower amounts of C22:0, C20:0, and C18:0 fatty acids. Moreover, the ceramide base is approximately 55% sphingosine and 45% dihydrosphingosine. No unsaturated N-acyl fatty acids were detected in either antigen.     

Purification and Characterization of an Extracellular Acid Proteinase from the Ectomycorrhizal Fungus Hebeloma crustuliniforme

Hebeloma crustuliniforme produced an extracellular acid proteinase in a liquid medium containing bovine serum albumin as the sole nitrogen source. The proteinase was purified 26-fold with 20% activity recovery and was shown to have a molecular weight of 37,800 (as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and an isoelectric point of 4.8 +/- 0.2. The enzyme was most active at 50 degrees C and pH 2.5 against bovine serum albumin and was stable in the absence of substrates at temperatures up to 45 degrees C and pHs between 2.0 and 5.0. Pepstatin A, diazoacetyl-dl-norleucine methylester, metallic ions Fe and Fe, and phenolic acids severely inhibited the enzyme activity, while antipain, leupeptin, N-alpha-p-tosyl-l-lysine chloromethyl ketone, and trypsin inhibitor inhibited the activity moderately. The proteinase hydrolyzed bovine serum albumin and cytochrome c rapidly compared with casein and azocasein but failed to hydrolyze any of the low-molecular-weight peptide derivatives tested.