scholarly journals Reductive Dechlorination of Tetrachloroethene to Ethene by a Two-Component Enzyme Pathway

1998 ◽  
Vol 64 (4) ◽  
pp. 1270-1275 ◽  
Author(s):  
Jon K. Magnuson ◽  
Robert V. Stern ◽  
James M. Gossett ◽  
Stephen H. Zinder ◽  
David R. Burris
Keyword(s):  
Enrichment Culture ◽  
Reductive Dehalogenation ◽  
Reductive Dehalogenase ◽  
Reversible Inhibition ◽  
Isolation And Characterization ◽  
Dehalococcoides Ethenogenes ◽  
Membrane Bound ◽  
Catalytic Mechanisms ◽  
Insight Into

ABSTRACT Two membrane-bound, reductive dehalogenases that constitute a novel pathway for complete dechlorination of tetrachloroethene (perchloroethylene [PCE]) to ethene were partially purified from an anaerobic microbial enrichment culture containing Dehalococcoides ethenogenes 195. When titanium(III) citrate and methyl viologen were used as reductants, PCE-reductive dehalogenase (PCE-RDase) (51 kDa) dechlorinated PCE to trichloroethene (TCE) at a rate of 20 μmol/min/mg of protein. TCE-reductive dehalogenase (TCE-RDase) (61 kDa) dechlorinated TCE to ethene. TCE,cis-1,2-dichloroethene, and 1,1-dichloroethene were dechlorinated at similar rates, 8 to 12 μmol/min/mg of protein. Vinyl chloride and trans-1,2-dichloroethene were degraded at rates which were approximately 2 orders of magnitude lower. The light-reversible inhibition of TCE-RDase by iodopropane and the light-reversible inhibition of PCE-RDase by iodoethane suggest that both of these dehalogenases contain Co(I) corrinoid cofactors. Isolation and characterization of these novel bacterial enzymes provided further insight into the catalytic mechanisms of biological reductive dehalogenation.

scholarly journals Isolation and characterization of a membrane protein from rat erythrocytes which inhibits lysis by the membrane attack complex of rat complement

1992 ◽  
Vol 284 (1) ◽  
pp. 169-176 ◽  
Author(s):  
T R Hughes ◽  
S J Piddlesden ◽  
J D Williams ◽  
R A Harrison ◽  
B P Morgan
Keyword(s):  
Affinity Purification ◽  
Membrane Attack Complex ◽  
Erythrocyte Membranes ◽  
Dependent Manner ◽  
Inhibitory Protein ◽  
Rat Erythrocytes ◽  
Butanol Extract ◽  
Isolation And Characterization ◽  
Membrane Bound

The membrane attack complex (MAC) of complement in humans is regulated by several membrane-bound proteins; however, no such proteins have so far been described in other species. Here we report the isolation and characterization of a rat erythrocyte membrane glycoprotein of molecular mass 21 kDa which inserts into cell membranes and is a potent inhibitor of the rat MAC. This protein, here called rat inhibitory protein (RIP), was first partially purified by column chromatography from a butanol extract of rat erythrocyte membranes. Monoclonal antibodies (Mabs) were raised against RIP and used for its affinity purification. Affinity-purified RIP was shown to inhibit in a dose-dependent manner the cobra venom factor (CVF)-mediated ‘reactive’ lysis of guinea pig erythrocytes by rat complement. Conversely, the anti-RIP MAbs 6D1 and TH9 were shown to markedly enhance the CVF-mediated lysis of rat erythrocytes by rat complement. RIP acted late in the assembly of the MAC (at or after the C5b-8 stage) and was releasable from the membranes of rat erythrocytes by phosphatidylinositol-specific phospholipase C. These features, together with its size, deglycosylation pattern and N-terminal amino acid sequence, lead us to conclude that RIP is the rat homologue of the human MAC-inhibitory protein CD59 antigen.

scholarly journals Substrate-dependent competition and cooperation relationships between Geobacter and Dehalococcoides for their organohalide respiration

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yongyi Liang ◽  
Qihong Lu ◽  
Zhiwei Liang ◽  
Xiaokun Liu ◽  
Wenwen Fang ◽  
...  
Keyword(s):  
Electron Donors ◽  
Community Stability ◽  
Organohalide Respiration ◽  
Competition And Cooperation ◽  
Free Competition ◽  
Isolation And Characterization ◽  
Geochemical Cycling ◽  
New Strategy ◽  
Insight Into

AbstractObligate and non-obligate organohalide-respiring bacteria (OHRB) play central roles in the geochemical cycling and environmental bioremediation of organohalides. Their coexistence and interactions may provide functional redundancy and community stability to assure organohalide respiration efficiency but, at the same time, complicate isolation and characterization of specific OHRB. Here, we employed a growth rate/yield tradeoff strategy to enrich and isolate a rare non-obligate tetrachloroethene (PCE)-respiring Geobacter from a Dehalococcoides-predominant microcosm, providing experimental evidence for the rate/yield tradeoff theory in population selection. Surprisingly, further physiological and genomic characterizations, together with co-culture experiments, revealed three unique interactions (i.e., free competition, conditional competition and syntrophic cooperation) between Geobacter and Dehalococcoides for their respiration of PCE and polychlorinated biphenyls (PCBs), depending on both the feeding electron donors (acetate/H2 vs. propionate) and electron acceptors (PCE vs. PCBs). This study provides the first insight into substrate-dependent interactions between obligate and non-obligate OHRB, as well as a new strategy to isolate fastidious microorganisms, for better understanding of the geochemical cycling and bioremediation of organohalides.

scholarly journals Isolation and Characterization of Membrane-Bound Arylamidases from Human Placenta and Kidney

1980 ◽  
Vol 104 (1) ◽  
pp. 155-165 ◽  
Author(s):  
Kunio HIWADA ◽  
Taketoshi ITO ◽  
Masako YOKOYAMA ◽  
Tatsuo KOKUBU
Keyword(s):  
Human Placenta ◽  
Isolation And Characterization ◽  
Membrane Bound

scholarly journals Molecular Characterization of the PceA Reductive Dehalogenase of Desulfitobacterium sp. Strain Y51

2002 ◽  
Vol 184 (13) ◽  
pp. 3419-3425 ◽  
Author(s):  
Akiko Suyama ◽  
Masaki Yamashita ◽  
Sadazo Yoshino ◽  
Kensuke Furukawa
Keyword(s):  
Escherichia Coli ◽  
Molecular Characterization ◽  
Specific Activity ◽  
Chlorinated Ethenes ◽  
Reductive Dehalogenation ◽  
Reductive Dehalogenase ◽  
Dna Fragment

ABSTRACT The tetrachloroethene (PCE) reductive dehalogenase (encoded by the pceA gene and designated PceA dehalogenase) of Desulfitobacterium sp. strain Y51 was purified and characterized. The expression of the enzyme was highly induced in the presence of PCE and trichloroethene (TCE). The purified enzyme catalyzed the reductive dehalogenation of PCE via TCE to cis-1,2-dichloroethene at a specific activity of 113.6 nmol · min−1 · mg of protein−1. The apparent Km values for PCE and TCE were 105.7 and 535.3 μM, respectively. Chlorinated ethenes other than PCE and TCE were not dehalogenated. However, the enzyme exhibited dehalogenation activity for various chlorinated ethanes such as hexachloroethane, pentachloroethane, 1,1,1,2-tetrachloroethane, and 1,1,2,2-tetrachloroethane. The pceA gene of Desulfitobacterium sp. strain Y51 was identified in a 2.8-kb DNA fragment and used to express the protein in Escherichia coli for the preparation of antibodies. Immunoblot analyses located PceA in the periplasm of the cell.

Biosynthesis of Spin-Labelled Lipids and Their Use in the Study of Biological Membranes: Isolation and Characterization of Membrane-Bound Spin-Labelled sn-3-Phosphatidic Acid-2-3H Prepared by Enzymatic Incorporation of Spin-Labelled Stearic Acid into sn-Glycero-3-phosphate-2-3H

1974 ◽  
Vol 52 (10) ◽  
pp. 884-893 ◽  
Author(s):  
N. Z. Stanacev ◽  
L. Stuhne-Sekalec ◽  
S. Schreier-Muccillo ◽  
I. C. P. Smith
Keyword(s):  
Phosphatidic Acid ◽  
Spin Label ◽  
Liver Microsomes ◽  
Biological Membranes ◽  
General Application ◽  
Isolation And Characterization ◽  
Spin Resonance ◽  
Membrane Bound ◽  
Guinea Pig Liver Microsomes

Spin-labelled 12-doxylstearic acid was covalently incorporated into sn-glycero-3-phosphate-2-3H yielding sn-3-phosphatidic acid-2-3H, a key intermediate in phospholipid biosynthesis, in a reaction catalyzed by isolated guinea-pig liver microsomes. It was found that at least 17.1% of the obtained sn-3-phosphatidic acid-2-3H contained spin label. Degradation of spin-labelled sn-3-phosphatidic acid-2-3H with the phospholipase A from Crotalus adamanteus yielded both lyso-sn-3-phosphatidic acid-2-3H and free fatty acids which were paramagnetic, establishing that the incorporated 12-doxylstearic acid occupies both sn-1- and sn-2-positions of the biosynthesized sn-3-phosphatidic acid-2-3H.A procedure for the preparation and isolation of biosynthetically spin-labelled radioactive sn-3-phosphatidic acid bound to the microsomal membrane was developed and the concentrations of spin-label and tritium were quantitatively determined. This procedure is believed to have a general application in the study of biological membranes. The electron spin resonance spectra and their quantitation are given and discussed for the spin-labelled sn-3-phosphatidic acid-2-3H in solution and in the membrane-bound form. Some general requirements for covalent spin labelling of biological membranes are discussed.

scholarly journals Isolation and characterization of an age-related antigen present on senescent human red blood cells

Blood ◽  
1981 ◽  
Vol 58 (2) ◽  
pp. 341-349
Author(s):  
EM Alderman ◽  
HH Fudenberg ◽  
RE Lovins
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Double Immunodiffusion ◽  
Specific Density ◽  
Human Red Blood Cells ◽  
Rbc Membrane ◽  
Isolation And Characterization ◽  
Age Related ◽  
Membrane Bound

Autologous membrane-bound IgG was isolated from a subpopulation of human red blood cells (RBC) with specific density greater than 1.110, by affinity chromatography of purified RBC membrane glycoprotein preparations using immobilized wheat germ agglutinin and immobilized anti-human immunoglobulin (Ig) as immunoabsorbents. The Ig-containing population thus obtained, when further separated by chromatography on Sephadex G-200 in the presence of chaotropic agents, yielded four peaks (Ia, Ib, II, and III). Double immunodiffusion revealed the presence of Ig in the first three peaks (IgM in peak Ia, IgA in Ib, and IgG in II) but not in peak III. Peak III was precipitated by the Ig-containing peaks (Ia, Ib, and II) in immunodiffusion assays, suggesting that the antigenic membrane determinants responsible for the binding of autologous Ig to senescent human RBC were contained in this peak (III). Peaks Ia, Ib and II precipitate purified asialoglycophorin; peak III was reactive with purified autoantibodies directed against asialoglycophorin. These results suggest that an age-related antigenic determinant(s) present on senescent human RBC is exposed by desialylation of the major sialoglycoprotein component of the RBC membrane.

Sign in / Sign up

Export Citation Format

Share Document