Direct Measurement of Iodine Production by Sonic Extracts of Polymorphonuclear Leukocytes

1971 ◽  
Vol 17 (5) ◽  
pp. 392-396 ◽  
Author(s):  
Lawrence R DeChatelet ◽  
Charles E McCall ◽  
M Robert Cooper
Keyword(s):  
Absorption Spectrum ◽  
Kinetic Data ◽  
Polymorphonuclear Leukocytes ◽  
Enzymatic Reaction ◽  
Human Neutrophils ◽  
Enzyme Kinetic ◽  
Ph Optimum ◽  
Beef Liver ◽  
Free Iodine ◽  
High Concentrations

Abstract We describe an enzymatic reaction between iodide ion, H2O2, and neutrophil sonicates, in which free iodine is formed. Some characteristics of the reaction are: (a) it is catalyzed by sonic extracts of human neutrophils, by purified horseradish peroxidase, or purified human myeloperoxidase, but not by sonic extracts of rabbit alveolar macrophages or beef liver catalase; (b) iodine is the product, as shown by its absorption spectrum and the absorption spectrum of the starch adduct; (c) the reaction is proportional to the amount of neutrophil sonicate added, and has a pH optimum near 4.0. Reaction is not linear with respect to time, owing to denaturation of the enzyme. Kinetic data indicate that the enzyme may be allosteric with respect to iodide and is inhibited by high concentrations of H2O2. These represent possible sources of control of the reaction.

scholarly journals Properties of NADH-cytochrome-b5 reductase from human neutrophils

Blood ◽  
1983 ◽  
Vol 62 (1) ◽  
pp. 152-157
Author(s):  
JA Badwey ◽  
AI Tauber ◽  
ML Karnovsky
Keyword(s):  
Reductase Activity ◽  
Cytochrome B5 ◽  
Extraction Procedure ◽  
Human Neutrophils ◽  
Ph Optimum ◽  
Beef Liver ◽  
Cytochrome B5 Reductase ◽  
Ferricyanide Reductase ◽  
Membrane Bound ◽  
Nadh Cytochrome

An NADH-ferricyanide reductase activity of ca. 170 nmole ferricyanide reduced/min/10(7) cells is present in the membrane fraction of human neutrophils. This membrane-bound activity constitutes ca. 85% of the total NADH-ferricyanide reductase activity that is present in these cells. The enzyme(s) readily utilize(s) purified cytochrome-b5 from beef liver as an electron acceptor. No other physiologic electron acceptors tested (e.g., ubiquinone-30, menadione) were active. The specificities of electron donors (e.g., NADH congruent to deamino-NADH much greater than NADPH) and acceptors (e.g., Fe(CN)6–3 greater than 2,6-dichlorophenol-indophenol much greater than O2) for the enzyme(s) in unfractionated membranes, along with action of inhibitors (e.g., ADP, p-chloromercuribenzoate) and the pH optimum, indicate that virtually all of the membrane-bound ferricyanide reductase activity in these cells is NADH-cytochrome-b5 reductase. This reductase, however, is only slightly solubilized (ca. 10%) by a phosphate buffer extraction procedure that is effective with the liver enzyme.

scholarly journals Properties of NADH-cytochrome-b5 reductase from human neutrophils

Blood ◽  
1983 ◽  
Vol 62 (1) ◽  
pp. 152-157 ◽  
Author(s):  
JA Badwey ◽  
AI Tauber ◽  
ML Karnovsky
Keyword(s):  
Reductase Activity ◽  
Cytochrome B5 ◽  
Extraction Procedure ◽  
Human Neutrophils ◽  
Ph Optimum ◽  
Beef Liver ◽  
Cytochrome B5 Reductase ◽  
Ferricyanide Reductase ◽  
Membrane Bound ◽  
Nadh Cytochrome

Abstract An NADH-ferricyanide reductase activity of ca. 170 nmole ferricyanide reduced/min/10(7) cells is present in the membrane fraction of human neutrophils. This membrane-bound activity constitutes ca. 85% of the total NADH-ferricyanide reductase activity that is present in these cells. The enzyme(s) readily utilize(s) purified cytochrome-b5 from beef liver as an electron acceptor. No other physiologic electron acceptors tested (e.g., ubiquinone-30, menadione) were active. The specificities of electron donors (e.g., NADH congruent to deamino-NADH much greater than NADPH) and acceptors (e.g., Fe(CN)6–3 greater than 2,6-dichlorophenol-indophenol much greater than O2) for the enzyme(s) in unfractionated membranes, along with action of inhibitors (e.g., ADP, p-chloromercuribenzoate) and the pH optimum, indicate that virtually all of the membrane-bound ferricyanide reductase activity in these cells is NADH-cytochrome-b5 reductase. This reductase, however, is only slightly solubilized (ca. 10%) by a phosphate buffer extraction procedure that is effective with the liver enzyme.

scholarly journals Treatment of Enzyme Kinetic Data

1967 ◽  
Vol 242 (18) ◽  
pp. 4045-4052 ◽  
Author(s):  
Carl Frieden
Keyword(s):  
Kinetic Data ◽  
Enzyme Kinetic

scholarly journals Regulation of CD18 expression in human neutrophils as related to shape changes

1993 ◽  
Vol 106 (2) ◽  
pp. 493-501
Author(s):  
A. Volz
Keyword(s):  
Phorbol Myristate Acetate ◽  
Surface Expression ◽  
Cytochalasin D ◽  
Human Neutrophils ◽  
Chemotactic Peptide ◽  
Myristate Acetate ◽  
Surface Distribution ◽  
Quantitative Expression ◽  
High Concentrations ◽  
Shape Changes

The study analyses the distribution and quantitative expression of surface CD18 of neutrophils exposed to distinct stimuli that produce different types of continuous shape changes, including types that are associated with locomotion and others that are not. The chemotactic peptide N-formyl-L-norleucyl-L-leucyl-L-phenylalanine, colchicine and nocodazole were used to induce a polarized locomotor morphology, phorbol myristate acetate, 1,2-dioctanoylglycerol and 1-oleoyl-2-acetyl-glycerol to induce non-polar motile cells ruffling all over the surface and 2H2O to induce non-polar cells performing circus movements as have been previously described. Except for colchicine and nocodazole, these stimuli increased surface expression of CD18. Thus, stimulated shape changes are frequently, though not always, associated with increased surface expression of CD18. High concentrations (10(−7) to 10(−5) M) of phorbol myristate acetate but not of chemotactic peptide induced down-regulation of surface CD18. Cytochalasin D (10(−4) M) stimulated CD18 expression even though it inhibited shape changes. The surface distribution of CD18 determined by light microscopy was uniform in unstimulated cells or in various forms of stimulation except for cells treated with 10(−5) M cytochalasin D. Cytochalasin D (10(−5) M) produced CD18 accumulation at the pole opposite the F-actin cap. Experiments with colchicine, nocodazole, 2H2O and cytochalasin D suggest that microtubules as well as microfilaments modulate surface expression of CD18. The results suggest that protein kinase C and phosphatases play a role in regulating surface expression of CD18 in neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Pre-fermentative treatment of a model wine with aim to serve as a functional food with decreased alcohol content

2017 ◽  
Vol 63 (01) ◽  
pp. 47-53
Author(s):  
Irina Mladenoska ◽  
Verica Petkova ◽  
Tatjana Kadifkova Panovska
Keyword(s):  
Enzyme Activity ◽  
Gluconic Acid ◽  
Functional Food ◽  
Ph Value ◽  
Enzymatic Reaction ◽  
Alginate Beads ◽  
High Concentration ◽  
Ph Optimum ◽  
Enzyme Preparations ◽  
Initial Ph

The effect of substrate concentration on the enzyme activity in the reaction of glucose conversion into gluconic acid was investigated by using three different enzyme preparations in media with two different glucose concentrations. The media were simulating the conditions in the must, thus named as minimal model must, and were composed form combination of several organic acids and glucose. Those media were having initial pH of 3.5 that is a very unfavorable for glucose oxidase activity having a pH optimum at the pH value of 5.5. Among the three preparations used, the bakery additive, Alphamalt Gloxy 5080, was the most active in the medium with glucose concentration of 10 g/L, showing conversion of more than 70% for the period of 24 h, while the same enzyme preparation in the medium with 100 g/L glucose converted only about 7% of glucose. The pH value of the medium at the beginning and at the end of the enzymatic reaction was a good indicator of the enzyme activity. It seems that for the conversion of glucose in higher concentration, enzymatic preparation in high concentration should also be used. The preliminary attempt of immobilization of two preparations of glucose oxidases in alginate beads was also performed and a successful immobilization procedure for utilization in food industry was preliminarily developed. Keywords: glucose oxidases, enzymatic pretreatment, glucose, gluconic acid, model wine, functional food

Characterization and distribution of arginine kinase in the tissues of the scorpion, Palamneus phipsoni

1985 ◽  
Vol 63 (10) ◽  
pp. 2262-2266 ◽  
Author(s):  
A. V. Arjunwadkar ◽  
S. Raghupathi Rami Reddy
Keyword(s):  
Molecular Weight ◽  
Gel Electrophoresis ◽  
Alimentary Canal ◽  
Polyacrylamide Gel Electrophoresis ◽  
Arginine Kinase ◽  
High Specificity ◽  
Ph Optimum ◽  
High Concentrations ◽  
Claw Muscle ◽  
Slight Inhibition

Arginine kinase in claw muscle extracts of the scorpion, Palamneus phipsoni, was characterized. The enzyme, with a pH optimum of 8.5 in the direction of phosphoarginine synthesis, showed activation by Mg2+, high specificity towards L-arginine as the guanidino substrate, slight inhibition by high concentrations of L-arginine and ATP, and a molecular weight of 33 500. On polyacrylamide gel electrophoresis at pH 8.3 the enzyme migrated to the anode as a single molecular species. In addition to the claw muscle, the enzyme activity was also found to be present in the heart, alimentary canal, hepatopancreas, and nervous system. In general, scorpion muscle arginine kinase appears to be similar in its properties to the enzyme from other arthropods.

The assay and partial characterization of 3β-hydroxysteroid sulfotransferase of the hamster epididymis

1985 ◽  
Vol 63 (1) ◽  
pp. 71-76 ◽  
Author(s):  
M. Bouthillier ◽  
G. Bleau ◽  
A. Chapdelaine ◽  
K. D. Roberts
Keyword(s):  
Organic Phase ◽  
Enzyme Preparation ◽  
Enzymatic Reaction ◽  
Partial Characterization ◽  
Optimal Conditions ◽  
Steroid Nucleus ◽  
Optimum Ph ◽  
High Concentrations

Using a partially purified enzyme preparation obtained from hamster epididymis, a simple assay has been developed to measure the sulfurylation of dehydroisoandrosterone (DHA) and desmosterol in the presence of 3′-phosphoadenosine 5′-phospho[35S]sulfate ([35S]PAPS). After stopping the enzymatic reaction with methanol and KCl, the 35S-labelled steroid sulfates are readily extracted into an organic phase. Optimal conditions for the sulfurylation of the two steroids were compared; optimum pH is 8.7 for DHA and 9.8 for desmosterol. Sulfoconjugation of desmosterol increases with magnesium concentrations up to 6 mM, while 40 mM concentrations of the divalent ion are required for the optimal sulfurylation of DHA. Maximum sulfurylation of these steroids requires the presence of 15 mM cysteine. Michaelis–Menten kinetics are observed with DHA which has an apparent Km of 32 μM, while desmosterol inhibits sulfotransferase activity at high concentrations. Saturation of the enzyme with PAPS results in an allosteric behaviour. Only the 3β-hydroxyl function of the steroid nucleus appears to be an appropriate sulfate acceptor for the epididymal hydroxysteroid sulfotransferase.

scholarly journals The quantitative analysis of ligand binding and initial-rate data for allosteric and other complex enzyme mechanisms

1976 ◽  
Vol 153 (1) ◽  
pp. 101-117 ◽  
Author(s):  
W G Bardsley
Keyword(s):  
Kinetic Data ◽  
Quantitative Data ◽  
Initial Rate ◽  
Graphical Methods ◽  
Enzyme Kinetic ◽  
Rate Data ◽  
Curve Shape ◽  
High Substrate Concentration ◽  
Complex Curve ◽  
Complex Curves

1. The eight methods for plotting enzyme kinetic data are classified and analysed, and it is shown how, in each case, it is only possible to obtain quantitative data on the coefficients of the lowest- and highest-degree terms in the rate equation. 2. The combinations of coefficients that are accessible experimentally from limiting slopes and intercepts at both low and high substrate concentration are stated for all the graphical methods and the precise effects of these on curve shape in different spaces is discussed. 3. Ambiguities arising in the analysis of complex curves and certain special features are also investigated. 4. Four special ordering functions are defined and investigated and it is shown how knowledge of these allows a complete description of all possible complex curve shapes.

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