Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0272170 (SDS)
 50,377 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During purification of tau protein kinase I and II from the bovine brain extract, a new tau protein kinase was detected and purified with phosphocellulose, gel filtration, S-Sepharose and AF-Heparin column chromatography. The molecular mass of the enzyme was determined to be 32 kDa by gel filtration and activity staining on SDS-PAGE. The enzyme is a Ser/Thr protein kinase phosphorylating tau, beta-tubulin, MAP2 and alpha-casein. Employing many synthetic peptides, the recognition site of this enzyme appears to be -SR-. The enzyme requires no second messenger and is inhibited with high concentration of heparin, but not by inhibitors of CKI. These results indicate that this enzyme, tau-tubulin kinase is novel and distinct from TPKI, II and CKI, II.
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PMID:A novel tau-tubulin kinase from bovine brain. 755 43

Vascular endothelial growth factor (VEGF) is a mitogen for cultured endothelial cells, and a potent angiogenic factor in vivo. Incubation of 125I-VEGF with human or bovine serum led to the formation of 125I-VEGF containing complexes that had a molecular mass greater than 300 kDa. These complexes were specifically immunoprecipitated with anti-human alpha 2-macroglobulin (alpha 2M) antibodies. Similar high molecular weight complexes were formed when 125I-VEGF was incubated with commercially available alpha 2M. The 125I-VEGF.alpha 2M complexes were resistant to boiling in the presence of SDS. The formation of 125I-VEGF.alpha 2M complexes was inhibited by iodoacetic acid, indicating that free sulfhydryl groups are required for complex assembly. Tryptic digestion of alpha 2M did not affect its VEGF binding ability. Tryptic digestion of 125I-VEGF.alpha 2M complexes on the other hand, resulted in the degradation of bound 125I-VEGF, indicating that alpha 2M does not protect bound 125I-VEGF from proteolytic digestion. The binding of 125I-VEGF to alpha 2M was partially inhibited by an excess of basic fibroblast growth factor. Other growth factors which bind to alpha 2M, such as platelet-derived growth factor and insulin, did not inhibit the binding of 125I-VEGF. The binding of VEGF to alpha 2M inhibited its receptor binding ability, indicating that alpha 2M may function as a VEGF removal and inactivation factor. Heparin and heparan sulfate, but not other glycosaminoglycans such as chondroitin sulfate, efficiently inhibited the binding of 125I-VEGF to alpha 2M. It is possible that heparin-like molecules released from extracellular matrixes could prevent the inactivation of VEGF by alpha 2M resulting in the potentiation of processes such as tumor angiogenesis.
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PMID:Vascular endothelial growth factor is inactivated by binding to alpha 2-macroglobulin and the binding is inhibited by heparin. 768 26

Staphylococcal neutral phosphatase (NPtase) was purified from two Staphylococcus aureus strains by sequential high salt extraction, ultracentrifugation and ion exchange chromatography. The enzyme showed maximum phosphatase activity at neutral pH, appeared as two bands in SDS-PAGE (31 and 32 kDa), and the isoelectric point was > 10. No close similarity between NPtase and other known bacterial proteins in respect of their N-terminal amino acid sequences was found. Purified NPtase bound rat and human polyclonal IgG [intact and F(ab')2 fragments], IgM, IgA, intact myeloma immunoglobulins, myeloma light chains, gamma heavy chain and, with a much lower affinity, Fc fragments. Furthermore, NPtase can bind serum albumin. Heparin, a highly negatively charged molecule, significantly inhibited NPtase binding to immunoglobulins and HSA, but did not inhibit the binding of specific antibodies to NPtase; this indicates that charge interactions are important. The newly characterized staphylococcal phosphatase with binding properties for immunoglobulin is an interesting bacterial protein that could be involved in post-infectious sequelae.
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PMID:Staphylococcal neutral phosphatase. A highly cationic molecule with binding properties for immunoglobulin. 788 57

Midkine (MK) is a heparin-binding growth/differentiation factor with a molecular weight of 13 kDa, and is structurally unrelated to fibroblast growth factors (FGF). We studied MK-binding proteins in order to clarify the action mechanism of MK. A 100-kDa protein was identified in PYS-2, 3T3, and L cells as an MK-binding protein by a ligand blot experiment. This MK-binding protein was purified by affinity chromatography on an MK-agarose column followed by SDS polyacrylamide gel electrophoresis. Sequence determination of N-terminal 23 amino acid residues revealed that the MK-binding protein was nucleolin, a major nucleolar protein, which functions as a shuttle protein between the nucleus and cytoplasm and is located also on the cell surface. Heparin-binding growth associated molecule (HB-GAM), which has 50% sequence identity with MK, fused to maltose-binding protein also bound to nucleolin. On the other hand, basic FGF (bFGF) scarcely bound to nucleolin in the absence of heparin, while both MK and bFGF bound weakly to nucleolin in the presence of heparin. Nuclear localization of MK was shown in hemangioma cells by immunohistochemical staining. These findings supported the hypothesis that parts of the MK and HB-GAM are translocated to the nucleus after binding with nucleolin.
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PMID:Identification of nucleolin as a binding protein for midkine (MK) and heparin-binding growth associated molecule (HB-GAM). 789 34

We attempted to identify the factor that stimulated prostacyclin (PGI2) production using conditioned medium from cultured human diploid fibroblast cells subjected to a series of purification steps using h.p.l.c. on DEAE-5PW, Heparin-5PW, Protein-Pak 300, and an insulin-like growth factor-1 ligand affinity column. The purified prostacyclin-stimulating factor (PSF) ran as a single band with a molecular mass of 31 kDa by SDS/PAGE. Analysis of the purified PSF by C4 reversed-phase h.p.l.c. showed a single sharp peak in 31% (v/v) acetonitrile. The material was purified 8000-fold with an overall yield of about 18%. The purified PSF stimulated PGI2 production by cultured bovine aortic endothelial cells at a concentration of about 10 ng/ml; maximal stimulation was achieved at a concentration of 25 ng/ml. A cDNA coding for PSF was cloned and sequenced, revealing an apparently novel protein with no obvious sequence similarity to known proteins.
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PMID:Purification and molecular cloning of prostacyclin-stimulating factor from serum-free conditioned medium of human diploid fibroblast cells. 798 Apr 22

There are three selenium-containing proteins in human plasma: glutathione peroxidase (GSH-Px-P), albumin and selenoprotein Ph, the human analogue to selenoprotein P from rat plasma. Selenoprotein Ph was separated from the two other selenium-containing proteins by Heparin Sepharose chromatography and was shown to have about 60-70% of the total plasma selenium, while both GSH-Px-P and albumin contain about 15%. A 2588-fold purification from human plasma was achieved by using a four-step procedure. SDS-PAGE of the purified selenoprotein revealed, besides one contaminant selenium-free protein band at about 70 kDa, one selenium-containing band ranging from 54 to 67 kDa with a maximum at 63 kDa. This microheterogeneity, also recognized by IEF, may be due to the glycprotein nature of the selenoprotein Ph. The determination of the molecular mass of the native protein varied from 65 kDa using gel filtration on Fraktogel HW 55 to 89 kDa on Sephacryl S-200 HR, suggesting an interaction between the gel-matrices and selenoprotein Ph.
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PMID:Purification of selenoprotein Ph from human plasma. 801 51

To investigate the mechanism whereby heparin can modulate the activity of serine proteinases, bovine trypsin was chosen as reference and treated with heparin at 10, 100 and 200 micrograms/ml, in buffer solvents, with and without incubation at 37 degrees C. Heparin caused rapid, buffer- and pH-dependent decrease in trypsin solubility due to the generation of insoluble fragments from proteinase. Desalting treatments variously restored solubility by removing insoluble material. UV absorption and fluorescence emission spectra revealed significant heparin-induced conformational alterations in the trypsin molecule, the maximal effect being apparent at a proteinase-to-heparin molar ratio ranging from 1.6 to 1.0. The involvement of the catalytic sites of trypsin by heparin was further confirmed by the significant reduction in the difference absorption spectra of proflavine. Both proteolytic and esterolytic activities of trypsin were shown to be markedly decreased by heparin, especially after 5 h incubation at 37 degrees C. However, when the proteolytic and esterolytic activities of trypsin were measured on fresh solutions not submitted to desalting treatments, variable activation instead of inhibition of both activities was observed in the presence of heparin, this effect waning spontaneously in time or after desalting treatment. The paradoxical increase in functional activities was not inhibited by soybean trypsin inhibitor and was accompanied by denaturation and fragmentation of the proteinase as demonstrated by spectroscopic analyses and SDS-PAGE of fresh solutions. The results obtained indicated that heparin causes a rapid, time- and temperature-dependent conformational alteration of trypsin with irreversible denaturation and degradation of the proteinase. The underlying mechanism appears to be heparin-catalyzed oxidative degradation of trypsin due to liberation of oxygen radicals which are also responsible for the temporary increase in catalytic functions.
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PMID:Heparin-induced structural and functional alterations of bovine trypsin. 804 13

Erythrocyte Band 3 protein (Band 3), brain microtubule associated protein 2 (MAP2), and tubulin were phosphorylated to high stoichiometries (1-6 mol Pi/mol protein) on tyrosine residues using a rat spleen protein-tyrosine kinase in the presence of polylysine. After total removal of polylysine, the quantitatively phosphorylated proteins as well as tyrosine-glutamate copolymer [Poly(Glu4, Tyr1)], which was also phosphorylated (1.5 mol/mol) by the kinase, were employed to assay rat liver protein-tyrosine phosphatases (PTPases). Of the four partially purified PTPases termed L1, L2, L3, and L4, PTPase L1 was previously purified to homogeneity and demonstrated to be a novel enzyme with sequence similarity to src-homology region 2 [Hiraga, A. et al. (1992) Eur. J. Biochem. 209, 195-206]. In the present work PTPase L2 was purified to near homogeneity by a procedure involving chromatography on DEAE-cellulose, Blue Sepharose CL-6B, hydroxylapatite, Phenyl Sepharose CL-4B, and TSKgel Heparin-5PW. PTPase L2 was purified 20,000-fold with a recovery of 0.9% from the extract and 0.005 mg was isolated from 300 g of liver. The highly purified PTPase L2 showed a major protein band of 36 kDa on SDS/polyacrylamide gel electrophoresis. PTPase L2 had a specific activity of about 6,000 nmol of P1 released min-1.mg-1 toward either Band 3 or poly(Glu4, Tyr1), the values being within the range of those obtained for PTPases purified thus far. PTPase L2 dephosphorylated Band-3 9-fold and 5-fold faster than tubulin and MAP2, respectively, under the assay conditions employed.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of a rat liver protein-tyrosine phosphatase similar to human placental PTPase-1B using quantitatively phosphorylated protein substrates. 809 45

Sialidase activities of rabbit blood cells and serum were measured. The leucocyte particulate fraction showed the highest specific activity of sialidase towards mixed gangliosides and sialyllactose, and the cytosolic fraction showed for fetuin. Predominant sialidase activity in the blood was detected in erythrocyte particulate fraction when mixed gangliosides were used as substrate. The sialidase for ganglioside was solubilized from the erythrocyte ghosts by using Triton X-100. The solubilized sialidase was purified 1886-fold by sequential chromatographies on DEAE-cellulose, EAH-Sepharose 4B, Octyl-Sepharose CL-4B, Sephadex G-100, concanavalin-A--Sepharose, N-(p-aminophenyl)oxamic acid-agarose and Heparin-Sepharose CL-6B. The optimum pH of purified sialidase was 4.5 for ganglioside mixture, and this enzyme exhibited M(r) = 48,000 by gel filtration. When the purified sialidase was subjected to SDS/PAGE, a major sialidase-active protein band at M(r) = 54,000 and another fainter inactive protein band with M(r) = 115,000 were observed. The purified enzyme was active towards oligosaccharides, gangliosides, fetuin glycopeptide and 4-methylumbelliferyl alpha-D-N-acetylneuraminic acid except for glycoproteins tested. Fe2+, Fe3+ and dithiothreitol significantly inhibited the enzyme activity, while Triton X-100 activated the enzyme. Inside-out vesicles and unsealed ghosts of rabbit erythrocyte showed the sialidase activity for mixed gangliosides but not for resealed ghosts or intact erythrocytes. These results indicate that the active site of this sialidase is oriented mainly on the inside of the erythrocyte membrane and not on the outside. Treatment of rabbit erythrocyte unsealed ghosts with phosphatidylinositol-specific phospholipase C liberated no sialidase activity toward mixed gangliosides from the ghosts.
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PMID:Sialidase in rabbit blood. Characterization of sialidase purified from rabbit erythrocyte membrane. 817 46

We have previously shown that peptides derived from the thrombospondin sequence, CSVTCG, promoted tumor cell adhesion. To further investigate this observation, the CSVTCG-tumor cell adhesion receptor from A549 human lung adenocarcinoma cells was isolated and characterized. A single protein peak was isolated by CSVTCG affinity chromatography which also analyzed as a single peak by anion exchange chromatography. The purified protein had a pI of 4.7 and analyzed on SDS-gels as a single band of M(r) = 50,000 under nonreducing conditions and as two protein bands of M(r) = 50,000, and 60,000 under reducing conditions. Purified CSVTCG binding protein (CBP) bound either CSVTCG- or TSP-Sepharose but showed little interaction with either VCTGSC- or BSA-Sepharose. CBP was cell surface exposed. CSVTCG derivatized with [125I] Bolton-Hunter reagent was taken up by cells in a dose-dependent manner and the cell association was inhibited with a monospecific polyclonal anti-CBP antibody. Examination of the cell proteins crosslinked to labeled CSVTCG by SDS-gel electrophoresis revealed one band that comigrated with purified CPB. Using an in vitro binding assay, purified CBP bound mannose, galactose, and glucosamine-specific lectins. CBP bound TSP saturably and reversibly. The binding was Ca+2/Mg+2 ion dependent and inhibited with fluid phase TSP and anti-CBP. Little or no binding was observed on BSA, fibronectin, GRGES, and GRGDS. Heparin, but not lactose, inhibited binding. Anti-CBP IgG and anti-CSVTCG peptide IgG inhibited A549 cell spreading and adhesion on TSP but not on fibronectin and laminin. These results indicate that CBP and the CSVTCG peptide domain of TSP can mediate TSP-promoted tumor cell adhesion.
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PMID:Identification and characterization of a tumor cell receptor for CSVTCG, a thrombospondin adhesive domain. 842 Oct 63


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