scholarly journals Molecular forms of phosphatase and ribonuclease in phosphate deficient and N,N-dimethylmorpholinium chloride treated Spirodela oligorrhiza (Lemnaceae)

2015 ◽  
Vol 48 (1) ◽  
pp. 65-85 ◽  
Author(s):  
J. S. Knypl
Keyword(s):  
Gel Filtration ◽  
Molecular Forms ◽  
Membrane Material ◽  
Alkaline Phosphatases ◽  
Ph Optimum ◽  
Membrane Bound ◽  
Soluble Acid ◽  
Spirodela Oligorrhiza ◽  
Triton X ◽  
Membrane Bound Enzymes

Soluble, membrane bound, and extracellular phosphatases (EC 3.1.3.2 and 3.1.3.1) of control, N,N-dimethylmorphołinłum chloride (DMMC) treated, and phosphate deficient (-P) axenic <i>Spirodela oligorrhiza</i> plants were analysed by Sephadex G-150 gel filtration. Soluble, acid enzymes of control plants were separated into two molecular forms with apparent MW ≥ 400 000 and 85 000. Phosphatase with MW 34 000 replaced the latter isoenzyme in the presence of DMMC. Two alkaline enzymes with apparent MW 210 000 and 36 000 were detected in -P plants. Triton X-100 solubilized a number of acid and alkaline phosphatases from membrane material. DMMC caused the appearance of two membrane bound enzymes (MW 48 000 and 14 000) which were not detected in the control. Senescimg control and DMMC treated plants released an acid phosphatase (MW 48 000; pH optimum 5.2) into the nutrient medium. -P plants released, in addition ,an alkaline phosphatase (MW 170,000; pH optimum 7.8-8.2). Ribonucleases (EC 2.7.7.17.) with apparent MW 31000 and 28 000 daltons were induced by DMMC and -P, respectively.

scholarly journals Solubilization and characterization of pellet-associated human brain α-L-fucosidase activity

1985 ◽  
Vol 229 (3) ◽  
pp. 679-685 ◽  
Author(s):  
R L Hopfer ◽  
J A Alhadeff
Keyword(s):  
Human Brain ◽  
Isoelectric Focusing ◽  
Human Liver ◽  
Gel Filtration ◽  
Compelling Evidence ◽  
Supernatant Fluid ◽  
Ph Optimum ◽  
Triton X ◽  
Soluble Supernatant

The pellet-associated portion of human brain alpha-L-fucosidase (which represents approx. 20% of the homogenate activity) was solubilized with 0.5% (w/v) Triton X-100, characterized with regard to several properties and compared with the corresponding properties of the soluble supernatant-fluid enzyme in an attempt to find a second alpha-L-fucosidase in human brain. The solubilized and soluble alpha-L-fucosidase activities exhibited complete stability after storage at 2-4 degrees C for up to 29 days, comparable thermostability after preincubation at 50 degrees C, comparable apparent Km values (0.07-0.08 mM) for 4-methylumbelliferyl alpha-L-fucopyranoside, comparable hydrophobicity, comparable isoelectric-focusing profiles (six major forms, with pI values between 4.5 and 5.8) and comparable immunoprecipitation curves (with the IgG fraction of antisera prepared against human liver alpha-L-fucosidase). Differences in three properties were found between solubilized and soluble alpha-L-fucosidase activities: the solubilized activity was less stable to storage at −20 degrees C, had a 0.5-pH-unit neutral shift in its pH optimum (6.0) and had smaller Mr forms after gel filtration on Sephadex G-200. The overall results indicate that the pellet-associated and soluble portions of human brain alpha-L-fucosidase are quite similar in most of their properties. Thus there is still no compelling evidence for the existence of a second mammalian alpha-L-fucosidase.

scholarly journals Purification and properties of l-mandelate dehydrogenase and comparison with other membrane-bound dehydrogenases from Acinetobacter calcoaceticus

1987 ◽  
Vol 248 (3) ◽  
pp. 871-876 ◽  
Author(s):  
M E Hoey ◽  
N Allison ◽  
A J Scott ◽  
C A Fewson
Keyword(s):  
Lactate Dehydrogenase ◽  
Ion Exchange ◽  
Gel Filtration ◽  
Acinetobacter Calcoaceticus ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Ph Optimum ◽  
Purification And Properties ◽  
Potential Inhibitors ◽  
Triton X

L-Mandelate dehydrogenase was purified from Acinetobacter calcoaceticus by Triton X-100 extraction from a ‘wall + membrane’ fraction, ion-exchange chromatography on DEAE-Sephacel, (NH4)2SO4 fractionation and gel filtration followed by further ion-exchange chromatography. The purified enzyme was partially characterized with respect to its subunit Mr (44,000), pH optimum (7.5), pI value (4.2), substrate specificity and susceptibility to various potential inhibitors including thiol-blocking reagents. FMN was identified as the non-covalently bound cofactor. The properties of L-mandelate dehydrogenase are compared with those of D-mandelate dehydrogenase, D-lactate dehydrogenase and L-lactate dehydrogenase from A. calcoaceticus.

scholarly journals Characterization of a secretase activity which releases angiotensin-converting enzyme from the membrane

1993 ◽  
Vol 292 (2) ◽  
pp. 597-603 ◽  
Author(s):  
S Y Oppong ◽  
N M Hooper
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Human Kidney ◽  
Soluble Form ◽  
Converting Enzyme ◽  
Ph Optimum ◽  
Secretase Activity ◽  
Sds Page ◽  
Microsomal Membranes ◽  
Membrane Bound ◽  
Triton X

Angiotensin-converting enzyme (ACE; EC 3.4.1.15.1) exists in both membrane-bound and soluble forms. Phase separation in Triton X-114 and a competitive e.l.i.s.a. have been employed to characterize the activity which post-translationally converts the amphipathic, membrane-bound form of ACE in pig kidney microvilli into a hydrophilic, soluble form. This secretase activity was enriched to a similar extent as other microvillar membrane proteins, was tightly membrane-associated, being resistant to extensive washing of the microvillar membranes with 0.5 M NaCl, and displayed a pH optimum of 8.4. The ACE secretase was not affected by inhibitors of serine-, thiol- or aspartic-proteases, nor by reducing agents or alpha 2-macroglobulin. The metal chelators, EDTA and 1,10-phenanthroline, inhibited the secretase activity, with, in the case of EDTA, an inhibitor concentration of 2.5 mM causing 50% inhibition. In contrast, EGTA inhibited the secretase by a maximum of 15% at a concentration of 10 mM. The inhibition of EDTA was reactivated substantially (83%) by Mg2+ ions, and partially (34% and 29%) by Zn2+ and Mn2+ ions respectively. This EDTA-sensitive secretase activity was also present in microsomal membranes prepared from pig lung and testis, and from human lung and placenta, but was absent from human kidney and human and pig intestinal brush-border membranes. The form of ACE released from the microvillar membrane by the secretase co-migrated on SDS/PAGE with ACE purified from pig plasma, thus the action and location of the secretase would be consistent with it possibly having a role in the post-translational proteolytic cleavage of membrane-bound ACE to generate the soluble form found in blood, amniotic fluid, seminal plasma and other body fluids.

scholarly journals Subcellular distribution and characterization of acetylcholinesterase activities from sheep platelets: relationships between temperature- dependence and environment

Blood ◽  
1990 ◽  
Vol 76 (4) ◽  
pp. 737-744
Author(s):  
J Sanchez-Yague ◽  
JA Cabezas ◽  
M Llanillo
Keyword(s):  
Acetylcholinesterase Activity ◽  
Break Point ◽  
Molecular Forms ◽  
Kinetic Properties ◽  
Multiple Molecular Forms ◽  
Key Enzyme ◽  
Membrane Bound ◽  
Hill Coefficients ◽  
Triton X

Acetylcholinesterase is a key enzyme in cholinergic neurotransmission for hydrolyzing acetylcholine and has been shown to possess arylacylamidase activity in addition to esterase activity. The enzyme is found at various loci, where its functional significance remains to be clarified, and it exists in multiple molecular forms. Sheep platelets have been shown to exhibit acetylcholinesterase activity associated with plasma membrane (Bp), endoplasmic reticulum (Cp), mitochondria granules (Dp), and soluble (As) fractions. These activities show differences in some physicochemical and kinetic properties. The soluble acetylcholinesterase is the most thermostable, and the enzyme from the Cp fractions shows the lowest affinity for the acetylthiocholine substrate and the strongest inhibition by fluoride. In all cases a noncompetitive inhibition of the enzyme by this ion is found. When membrane-bound acetylcholinesterases were assayed at temperatures between 12 degrees C and 33 degrees C, the Arrhenius plots of all activities exhibited a break point at about 17 degrees C. This discontinuity was abolished by addition of detergent to the assay medium (0.02% Triton X-100, final concentration). Their Hill coefficients were calculated in the presence of fluoride, showing unitary values in all cases, which points to a noncooperative effect and nonallosteric behavior in the particulate enzyme. These results suggest that the sheep platelet acetylcholinesterase associated with membrane-bound systems is modulated by the physical state of its environment, despite the fact that the enzyme might be lipid- or nonlipid-dependent.

Molecular Forms of Purified Cytoplasmatic and Membrane Bound Bovine-Brain-Acetylcholinesterase Solubilized by Different Methods

1981 ◽  
Vol 36 (11-12) ◽  
pp. 968-972 ◽  
Author(s):  
K.-P. Rueß ◽  
M. Liefländer
Keyword(s):  
Molecular Form ◽  
Bovine Brain ◽  
Water Soluble ◽  
Molecular Forms ◽  
Enzyme Complex ◽  
Detergent Enzyme ◽  
Neuronal Tissues ◽  
Membrane Bound ◽  
Triton X ◽  
Brain Acetylcholinesterase

Abstract Membrane bound, Triton X-100 solubilized bovine nucleus caudatus acetylcholinesterase is sedimenting in presence of Triton X-100 concentrations higher than the CMC as a 10.5 S-detergent-enzyme complex. There is evidence that this complex does neither represent the molecular enzyme arrangement present in the membrane, nor the molecular form originally released from the membrane. The purified, cytoplasmatic acetylcholinesterase is sedimenting as a 10.5 S-form too. This form is clearly to be distinguished from the detergent enzyme complex, for it is obviously not capable of aggregating, whereas the 10.5 S-detergent-enzyme complex aggregates on detergent removal to defined water soluble oligomers with sedimentation coefficients of 16 S (700000 ± 10000), 20.6 S (960000 ± 60000) and 23.3 S (~ 1200000). In contrast to acetylcholinesterase from erythrocytes this aggregation is not easily reversibly by incubation with Triton X-100, reflecting differences in the hydrophobic part of the enzymes. Purified acetylcholinesterase solubilized without detergent under autolytic or tryptic conditions is mainly sedimenting as a 4.5 S-form. Such slow sedimenting forms detected in crude solubilisates of neuronal tissues, may originate at least partially form autolytic solubilization.

Rat lingual lipase: partial purification, hydrolytic properties, and comparison with pancreatic lipase

1984 ◽  
Vol 247 (4) ◽  
pp. G385-G393 ◽  
Author(s):  
I. M. Roberts ◽  
R. K. Montgomery ◽  
M. C. Carey
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Pancreatic Lipase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Hydrolytic Activity ◽  
Partial Purification ◽  
Ph Optimum ◽  
Dodecyl Sulfate ◽  
Triton X

We have partially purified lingual lipase from the serous glands of rat tongue. With a combination of Triton X-100 extraction or Triton X-114 phase-separation techniques, Bio-Bead SM-2 treatment, dialysis, and gel filtration on Sephadex G-200 or Sephacryl S-300, we obtained a sparingly soluble lipid-free protein demonstrating hydrolytic activity against triglycerides and negligible phospholipase or cholesteryl esterase activities. Compared with homogenate, specific activities of the enzyme were enriched 3- to 5-fold prior to gel filtration and 10-fold after gel filtration. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration under denaturing conditions (6 M guanidine X HCl or 0.1% sodium dodecyl sulfate) revealed one major glycoprotein band with Mr approximately 50,000. Gel filtration of the active enzyme in 0.1% Triton X-100 gave an Mr approximately 270,000-300,000, suggesting extensive self-aggregation. With both tributyrin and triolein, the pH optimum of the purified enzyme was 4.0 and activity extended from pH 2.0 to 8.0. In contrast to purified human pancreatic lipase, lingual lipase hydrolyzed triglyceride emulsions and mixed micelles stabilized with both short-chain (dihexanoyl) and long-chain (egg) lecithin and were inhibited only slightly (18-25%) by micellar concentrations of two common bile salts, taurodeoxycholate and taurocholate. Our results suggest that the hydrolysis of dietary fat by lingual lipase may extend from the pharynx through the esophagus and stomach and into the upper small intestine.

scholarly journals Kinetic analysis of the type-1 proinsulin endopeptidase by a monoclonal antibody-based immunoadsorbent assay

1992 ◽  
Vol 286 (1) ◽  
pp. 223-229 ◽  
Author(s):  
E M Bailyes ◽  
J C Hutton
Keyword(s):  
Gel Filtration ◽  
Sensitive Assay ◽  
Reaction Products ◽  
Ph Optimum ◽  
Insulin Granules ◽  
Proinsulin Processing ◽  
A Chain ◽  
Triton X

A simple, rapid and sensitive assay for the type-1 endopeptidase (Arg-Arg cleaving) was developed by using an antiproinsulin monoclonal immunoadsorbent to separate reaction products from the substrate. The values obtained by this assay were identical with those obtained by an h.p.l.c.-based procedure and yielded similar values for the pH optimum (5.6) and Ca2+ activation (K0.5 = 2 mM). It was shown that the type-1 endopeptidase was readily solubilized by Triton X-114 (87 +/- 3%, n = 12) and partitioned principally into the aqueous phase at 30 degrees C (90.1 +/- 2.6%, n = 12). Activity was lost on gel filtration, but could be restored by adenosine 5′-[gamma-thio]triphosphate (K0.5 = 6 microM), 50 microM-dithiothreitol or 50 microM-Ca(2+)-trans-1,2-diaminocyclohexane-NNN'N'-tetra-acetic acid (CDTA), indicating that the enzyme was particularly sensitive to heavy metal ions. The Km obtained with proinsulin as substrate (13 +/- 1.7 microM) indicated that the enzyme works at close to its Vmax. in the nascent secretory granule. The Vmax. of the enzyme prepared from insulin granules (0.6% proinsulin converted/min) corresponded closely to the rate measured in vivo in rat islets. The type-1 endopeptidase also appears to be capable of binding to proinsulin in the region of the C-peptide/A-chain junction, since a peptide spanning this region was found to inhibit the 125I-proinsulin processing measured by this assay.

scholarly journals Purification and properties of the membrane-bound by hydrogenase from Desulfovibrio desulfuricans

1983 ◽  
Vol 209 (2) ◽  
pp. 445-454 ◽  
Author(s):  
W V Lalla-Maharajh ◽  
D O Hall ◽  
R Cammack ◽  
K K Rao ◽  
J Le Gall
Keyword(s):  
Specific Activity ◽  
Gel Filtration ◽  
Desulfovibrio Desulfuricans ◽  
Relative Molecular Mass ◽  
H2 Evolution ◽  
Cytochrome C3 ◽  
Ph Optimum ◽  
Purification And Properties ◽  
Heavy Metal Salts ◽  
Membrane Bound

The membrane-bound hydrogenase from the anaerobic sulphate-reducing bacterium Desulfovibrio desulfuricans (Norway strain) has been purified to homogeneity, with an overall 80-fold purification and a specific activity of 70 mumol of H2 evolved/min per mg of protein. The hydrogenase had a relative molecular mass of 58 000 as determined by gel filtration and was estimated to contain six iron atoms and six acid-labile sulphur groups per molecule. The absorption spectrum of the enzyme was characteristic of an iron-sulphur protein. The E400 and E280 were 28 500 and 109 000 M-1.cm-1 respectively. The e.s.r. of the oxidized protein indicated the presence of [4Fe-4S]3+ or [3Fe-3S]3+, and another paramagnetic centre, probably Ni(III). The hydrogenase was inhibited by heavy-metal salts, carbon monoxide and high ionic strength. However, it was resistant to inhibition by thiol-blocking and metal-complexing reagents. N-Bromosuccinimide totally inhibited the enzyme activity at low concentrations. The enzyme was stable to O2 over long periods and to high temperatures. It catalyses both H2-evolution and H2-uptake with a variety of artificial electron carriers. D. desulfuricans cytochrome C3, its natural electron carrier, had a high affinity for the enzyme (Km = 2 microns). Rate enhancement was observed when cytochrome C3 was added to Methyl Viologen in the H2-evolution assay. The pH optimum for H2-evolution was 6.5.

scholarly journals Purification and characterization of membrane-bound semicarbazide-sensitive amine oxidase (SSAO) from bovine lung

1998 ◽  
Vol 331 (1) ◽  
pp. 69-78 ◽  
Author(s):  
José M. LIZCANO ◽  
Keith F. TIPTON ◽  
Mercedes UNZETA
Keyword(s):  
Amine Oxidase ◽  
Gel Filtration ◽  
Integral Membrane Protein ◽  
Significant Activity ◽  
Bovine Plasma ◽  
Sds Page ◽  
Catalytically Active ◽  
Cibacron Blue 3Ga ◽  
Membrane Bound ◽  
Triton X

Semicarbazide-sensitive amine oxidase (SSAO) has been purified from bovine lung microsomes in a form which is catalytically active and stable to storage. The enzyme, an integral membrane protein, was solubilized with Triton X-100 and purification was achieved, in the presence of detergent, by chromatography with Cibacron Blue 3GA-agarose, hydroxylapatite, Lens culinaris-agarose, Resource Q-FPLC and gel filtration on Superdex 200 HR-FPLC. This is the first reported procedure for the extensive purification of a membrane-bound SSAO. The purified enzyme had an apparent Mr of 400000 but exhibited microheterogeneity with SDS/PAGE and isoelectric focusing, probably as a result of its glycoprotein nature. It behaved as a tetramer with subunits with apparent Mr values of 100. Antibodies raised towards the purified enzyme cross-reacted with the enzymes from human lung and bovine plasma. Redox-cycling staining and reaction with carbonyl reagents were consistent with the presence of a quinone cofactor, possibly topa quinone. The enzyme was also shown to contain two mol of Cu/mol of enzyme and removal of half of this bound copper resulted essentially in complete inhibition of enzyme activity. In contrast to the reported behaviour of the SSAO enzymes from plasma, the bovine lung enzyme was relatively insensitive to inhibition by cyanide, copper-chelating agents and amiloride. The specificity of the bovine lung enzyme was also narrower than reported for soluble SSAO. It catalysed the oxidative deamination of benzylamine, methylamine, 2-phenylethylamine and histamine but had no significant activity towards dopamine, 5-hydroxytryptamine, tryptamine or tyramine.

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