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PubMed1975

Rabbit liver pyridoxamine (pyridoxine) 5'-phosphate oxidase. Purification and properties.

Pyridoxamine (pyridoxine) 5'-phosphate oxidase (EC 1.4.3.5) has been purified 2000-fold from rabbit liver. The enzyme preparation migrates as a single protein and activity band on analytical disc gels containing 4,7, or 9 percent acrylamide, and as a single protein band on sodium dodecyl sulfate acrylamide gels. The oxidase is, therefore, homogeneous by these criteria. The pure enzyme catalyzes the following reactions in the presence of FMN: (See journal for formula). These activities copurify in the ratio of 1:1:1. Apparent K-m values are 10 muM for pyridoxamine-P, 30 muM for pyridoxine-P, and 40 nM for FMN. Apparent K-m values for N-(phosphopyridoxyl)amines range from 3.1 times 10-5 M to 1.6 times 10-3 M. The dissociation constant for FMN binding, determined by quenching of protein fluorescence, is 20 nM. The pH optima for all three types of substrates are broad, with maxima near pH 9. The pH dependence of FMN binding, measured by quenching of flavin fluorescence, has the same shape as the substrate activity profile. The holoenzyme has absorption maxima red-shifted from those of FMN to 380 nm and 448 nm, and exhibits spectral changes typical of flavoproteins upon reduction with dithionite. Its oxidation-reduction potential at pH 7 in phosphate buffer is -0.131 volt. The native enzyme has a molecular weight of 54,000 and is made up of two possibly identical polypeptide chains with molecular weights of 27,000. The applicability of proposed mechanisms of flavin catalysis to this flavoprotein is discussed.

Animals↗
PubMed1991

Comparison of the efficacy of cultures of cecal anaerobes as inocula to reduce Salmonella typhimurium colonization in chicks with or without dietary lactose.

The ability of anaerobic cultures from mature chicken cecal material stored at -70 C for 1 or 10 mo to reduce Salmonella typhimurium colonization of the ceca of young chicks was evaluated. Chick treatments consisted of per os inoculation with anaerobic cultures from the cecal materials and providing or not providing the chicks dietary lactose. Chicks were challenged per os at 3 days of age with 10(6) S. typhimurium. Chicks were killed on Day 10, and their cecal contents were analyzed for pH, oxidation-reduction potential, total short-chained volatile fatty acids (VFA), lactic acid, and the number of S. typhimurium per gram of cecal content. Cecal concentration of undissociated VFA was calculated. Dietary lactose produced a .66- to .87-unit decrease in cecal pH, and significant increases in cecal lactic acid concentrations, undissociated cecal acetic and propionic acid concentrations, and cecal oxidation-reduction potentials. The treatment of the combination of cecal anaerobes from the 1 mo-old cecal material and dietary lactose caused a greater reduction in S. typhimurium cecal colonization than any other treatment.

Animals↗
PubMed1987

Active-site cobalt(II)-substituted horse liver alcohol dehydrogenase: characterization of intermediates in the oxidation and reduction processes as a function of pH.

Substitution of Co(II) for the catalytic site Zn(II) of horse liver alcohol dehydrogenase (LADH) yields an active enzyme derivative, CoIIE, with characteristic Co(II) charge-transfer and d-d electronic transitions that are sensitive to the events which take place during catalysis [Koerber, S. C., MacGibbon, A. K. H., Dietrich, H., Zeppezauer, M., & Dunn, M. F. (1983) Biochemistry 22, 3424-3431]. In this study, UV-visible spectroscopy and rapid-scanning stopped-flow (RSSF) kinetic methods are used to detect and identify intermediates in the LADH catalytic mechanism. In the presence of the inhibitor isobutyramide, the pre-steady-state phase of alcohol (RCH2OH) oxidation at pH above 7 is characterized by the formation and decay of an intermediate with lambda max = 570, 640, and 672 nm for both aromatic and aliphatic alcohols (benzyl alcohol, p-nitrobenzyl alcohol, anisyl alcohol, ethanol, and methanol). By comparison with the spectrum of the stable ternary complex formed with oxidized nicotinamide adenine dinucleotide (NAD+) and 2,2',2''-trifluoroethoxide ion (TFE-), CoIIE(NAD+, TFE-), the intermediate which forms is proposed to be the alkoxide ion (RCH2O-) complex, CoIIE(NAD+, RCH2O-). The timing of reduced nicotinamide adenine dinucleotide (NADH) formation indicates that intermediate decay is limited by the interconversion of ternary complexes, i.e., CoIIE(NAD+, RCH2O-) in equilibrium CoIIE(NADH, RCHO). From competition experiments, we infer that, at pH values below 5, NAD+ and alcohol form a CoIIE(NAD+, RCH2OH) ternary complex. RSSF studies carried out as a function of pH indicate that the apparent pKa values for the ionization of alcohol within the ternary complex, i.e., CoIIE(NAD+, RCH2OH) in equilibrium CoIIE(NAD+, RCH2O-) + H+, fall in the range 5-7.5. Using pyrazole as the dead-end inhibitor, we find that the single-turnover time courses for the reduction of benzaldehyde, p-nitrobenzaldehyde, anisaldehyde, and acetaldehyde at pH above 7 all show evidence for the formation and decay of an intermediate. Via spectral comparisons with CoIIE-(NAD+, TFE-) and with the intermediate formed during alcohol oxidation, we identify the intermediate as the same CoIIE(NAD+, RCH2O-) ternary complex detected during alcohol oxidation.

Alcohol Dehydrogenase↗
PubMed1997

Catalytic properties of NAD(P)H:quinone oxidoreductase-2 (NQO2), a dihydronicotinamide riboside dependent oxidoreductase.

Human NAD(P)H:quinone acceptor oxidoreductase-2 (NQO2) has been prepared using an Escherichia coli expression method. NQO2 is thought to be an isoform of DT-diaphorase (EC 1.6.99.2) [also referred to as NAD(P)H:quinone acceptor oxidoreductase] because there is a 49% identity between their amino acid sequences. The present investigation has revealed that like DT-diaphorase, NQO2 is a dimer enzyme with one FAD prosthetic group per subunit. Interestingly, NQO2 uses dihydronicotinamide riboside (NRH) rather than NAD(P)H as an electron donor. It catalyzes a two-electron reduction of quinones and oxidation-reduction dyes. One-electron acceptors, such as potassium ferricyanide, cannot be reduced by NQO2. This enzyme also catalyzes a four-electron reduction, using methyl red as the electron acceptor. The NRH-methyl red reductase activity of NQO2 is 11 times the NADH-methyl red reductase activity of DT-diaphorase. In addition, through a four-electron reduction reaction, NQO2 can catalyze nitroreduction of cytotoxic compound CB 1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide]. NQO2 is 3000 times more effective than DT-diaphorase in the reduction of CB 1954. Therefore, NQO2 is a NRH-dependent oxidoreductase which catalyzes two- and four-electron reduction reactions. NQO2 is resistant to typical inhibitors of DT-diaphorase, such as dicumarol, Cibacron blue, and phenindone. Flavones are inhibitors of NQO2. However, structural requirements of flavones for the inhibition of NQO2 are different from those for DT-diaphorase. The most potent flavone inhibitor tested so far is quercetin (3,5,7,3',4'-. 6pentahydroxyflavone). It has been found that quercetin is a competitive inhibitor with respect to NRH (Ki = 21 nM). NQO2 is 43 amino acids shorter than DT-diaphorase, and it has been suggested that the carboxyl terminus of DT-diaphorase plays a role in substrate binding (S. Chen et al., Protein Sci. 3, 51-57, 1994). In order to understand better the basis of catalytic differences between NQO2 and DT-diaphorase, a human NQO2 with 43 amino acids from the carboxyl terminus of human DT-diaphorase (i.e., hNQO2-hDT43) has been prepared. hNQO2-hDT43 still uses NRH as an electron donor. In addition, the chimeric enzyme is inhibited by quercetin but not dicumarol. These results suggest that additional region(s) in these enzymes is involved in differentiating NRH from NAD(P)H.

Amino Acid Sequence↗
PubMed1975

Starvation and seizures. Observation on the electroconvulsive threshold and cerebral metabolism of the starved adult rat.

Acute starvation of adult rats resulted in a rise in the electroconvulsive threshold at 48 hours (P less than .10) and at 72 hours (P less than .01), but not at 24 hours. Biochemical correlates included (1) ketonemia and mild hypoglycemia in the blood; (2) a significant rise in the brain cytoplasmic phosphorylation potential and in the energy charge potential; (3) a shift in the brain cytoplasmic oxidation-reduction potential to a more oxidized state; (4) probable partial inhibitions in brain phosphofructokinase and pyruvate dehydrogenase; and (5) relatively small increases in brain sodium (4.1%), potassium (2.4%), and chloride (4.3%). No major differences were seen in brain water content or adenosine triphosphatase activity. The observed cerebral biochemical alterations are believed to be the consequence of increased ketone body utilization, although the precise relationship to the alteration in the electroconvulsive threshold remains unclear.

Adenosine Triphosphatases↗
PubMed1996

Paradoxical mitochondrial oxidation in perinatal hypoxic-ischemic brain damage.

Measurements of cytoplasmic and mitochondrial markers of the oxidation-reduction (redox) state of brain tissue were conducted in a perinatal animal model of cerebral hypoxia-ischemia to ascertain underlying biochemical mechanisms whereby ischemia (reduced oxygen and substrate supply) causes brain damage. Seven-day postnatal rats underwent unilateral common carotid artery ligation followed by exposure to 8% oxygen at 37 degrees C for 3 h. During the course of hypoxia-ischemia, the rat pups were quick frozen in liquid nitrogen and their brains processed for the enzymatic, fluorometric measurement of cerebral metabolites necessary for the calculation of intracellular pH and cytoplasmic and mitochondrial redox states. The results showed an early mitochondrial reduction followed by re-oxidation during the course of hypoxia-ischemia. The oxidation reflected a partial depletion in accumulated reducing equivalents and coincides temporally with the duration of hypoxia-ischemia required to convert selective neuronal necrosis into cerebral infarction. The findings suggest that perinatal cerebral hypoxia-ischemia is characterized more by a limitation of substrate than of oxygen supply to the brain, which may explain why glucose supplementation of the immature animal improves neuropathologic outcome, in contrast to adults.

Adenosine Diphosphate↗
PubMed1977

[The use of certain new O-benzoquinone derivatives as acceptor substrates in enzymatic oxidation of NADH].

A possibility of the use of new aliphatic and aminoarylic o-benzoquinone derivatives as acceptor substrates in NADH oxidation catalyzed by NAD(P)H: (acceptor)-oxidoreductase (EC 1.6.99.2) was demonstrated. The kinetic mechanism of this reaction was studied in a monosubstrate approach and the effective kinetic constants were determined. The stability of these o-benzoquinone derivatives in the oxidation-reduction reactions, including anzymic reduction and subsequent auto-oxidation of their diphenolic forms by oxygen, was substantiated using spectrophotometric techniques.

Kinetics↗
PubMed1972

Effects of nonpolar environments on the redox potentials of heme complexes.

A method has been described for measurement of the oxidation-reduction potentials of redox couples in nonaqueous solutions. This method has been applied to a study of the effect of a nonpolar environment on the redox potential of a heme complex. A positive potential difference of some 300 mV is observed for the measured redox potentials by comparison with reported values for the corresponding heme complex in aqueous solution. The proposal is made that the redox potentials of many high-potential cytochromes may be accounted for by a local heme environment of low-dielectric constant, characteristic of nonpolar amino-acid side chains, and that this factor may play a dominant role in the determination of the oxidation-reduction properties of these proteins.

Amino Acids↗
PubMed2004

Relating induced in situ conditions of raw chicken breast meat to pinking.

Our objective was to simulate the pink color defect in cooked chicken breast meat with treatment combinations that would induce measurable changes in the conditions of raw meat. In addition, the feasibility of using induced raw meat conditions to develop a logistic regression model for prediction of pinking was studied. Approximately 960 breast fillets from 2 plants with 2 replications were used for inducing in situ conditions with 16 combinations of sodium chloride, sodium tripolyphosphate, sodium erythorbate, and sodium nitrite (present and not present). Muscles in all treatments were subjected to individual injections, followed by tumbling, cooking, and chilling. Raw samples were analyzed for pH, oxidation-reduction potential, and pigment evaluation. Results indicated a significant role of induced in situ conditions of raw meat in the occurrence of pinking. Presence of 1 ppm or more of sodium nitrite in raw meat produced significant pinking of cooked meat. The light muscle color group was least affected and the dark group was most affected by induced pH, oxidation-reduction potential conditions, and metmyoglobin and nitrosopigment content. The predictive ability of the logistic model was more than 90% with nitrosopigment, pH, and reducing conditions being the most important factors. Moreover, validation of the model was confirmed by close association between observed pink samples and those predicted as pink.

Animals↗
PubMed1983

[Morpho-functional changes in the liver after exposure to cholinesterase inhibitors].

A single administration of chlorophos (trichlorophon) solution (600 mg/kg) (LD50) results in vacuolar distrophy appearing in the white rat liver and is especially pronounced in 2-4 days. Thirty minutes after the poisonous chemical is administered, butyrilcholinesterase (BChE) activity is inhibited by 90%, somewhat later oxidation-reduction enzymes activity decreases and alkaline phosphatase (APh) activity increases. Cytoplasm of hepatocytes is filled with glycogene and nearly deprived of RNA. Owing to the cytophotometric analysis of the enzymatic activity and the stereologic morphometry method, it has been possible to reveal a certain synchronism in the development of distrophic processes, in a decreasing activity of the oxidation-reduction enzymes and in a disturbed synthesis of glycogene and RNA. On the 6th day after chlorophos has been administered, succinate dehydrogenase and nicotinamide-adenine-dinucleotide-phosphate-diaphorase activity, as well as contents and distribution of RNA in hepatocytes reach their control values. BChE and APh activity does not restore. During the whole experiment there is not any statistically significant change in the volumetric part of the sinusoid capillaries and in the stellate reticuloendotheliocytes. Thus, the main effect of chlorophos action is a specific inhibition of ChE, that results in certain structural changes and in changes of the histoenzymatic parameters of the liver.

Alkaline Phosphatase↗
PubMed1974

The lactate dehydrogenase--reduced nicotinamide--adenine dinucleotide--pyruvate complex. Kinetics of pyruvate binding and quenching of coeznyme fluorescence.

The stopped-flow kinetic studies described in this and the following paper (Südi, 1974) demonstrate that a Haldane-type description of the reversible lactate dehydrogenase reaction presents an experimentally feasible task. Combined results of these two papers yield numerical values for the six rate constants defined by the following equilibrium scheme, where E represents lactate dehydrogenase: [Formula: see text] The experiments were carried out at pH8.4 at a relatively low temperature (6.3 degrees C) with the pig heart enzyme. Identification of the above two intermediates and determination of the corresponding rate constants actually involve four series of independent observations in these studies, since (a) the reaction can be followed in both directions, and (b) both the u.v. absorption and the fluorescence of the coenzymes are altered in the reaction, and it is shown that these two spectral changes do not occur simultaneously. Kinetic observations made in the reverse direction are reported in this paper. It is demonstrated that the fluorescence of NADH can no longer be observed in the ternary complex E(NADH) (Pyr). Even though the oxidation-reduction reaction rapidly follows the formation of this complex, the numerical values of k(-4) (8.33x10(5)m(-1).s(-1)) and k(+4) (222s(-1)) are easily obtained from a directly observed second-order reaction step in which fluorescent but not u.v.-absorbing material is disappearing. U.v.-absorption measurements do not clearly resolve the subsequent oxidation-reduction step from the dissociation of lactate. It is shown that this must be due partly to the instrumental dead time, and partly to a low transient concentration of E(NAD+) (Lac) in the two-step sequential reaction in which the detectable disappearance of u.v.-absorbing material takes place. It is estimated that about one-tenth of the total change in u.v. absorption is due to a ;burst reaction' in which E(NAD+) (Lac) is produced, and this estimation yields, from k(obs.)=120s(-1), k(-2)=1200s(-1).

Animals↗
PubMed1980

The chemical reactivity of fully maleylated cytochrome c.

The chemical reactivity of fully maleylated horse heart cytochrome c with oxidants, reductants, and iron ligands was studied in the presence and absence of MgCl2. In the absence of salt, the partly unfolded protein reacts rapidly with cyanide in the ferric state (k = 235 M-1s-1); the reaction is exothermic (delta H = -9.4 kcal/mol) and entropically unfavored (delta S = -7.0 e.u.). In 0.01 M MgCl2, the refoleded protein recovers the behavior towards cyanide of native cytochrome c. The oxidation-reduction potential of the refolded species is 190 mV. In the course of reduction of the unfolded form with dithionite, a reduced intermediate species (t 1/2 = 5.9 s) is observed; this species binds carbon monoxide rapidly, but the ligand dissociates thereafter. This shows that full maleylation does not disrupt the conformational stability of reduced cytochrome c.

Animals↗
PubMed1981

Concerning the form of biochemically active vanadium.

A survey has been made of the descriptive chemistry of vanadium as it pertains to physiological environments. Taking into account the vanadium concentration, pH, coordinating ligands and chelates, presence of other cations, oxidation-reduction potentials and the kinetics of the various vanadium-containing species, the following suggestions are made. Free vanadium ions will be monomeric. Monomeric vanadium(V) and vanadium(IV) will each exist in a specific hydrated form. Extracellular vanadium will be in the vanadate, Vv, form. Intracellular vanadium will most likely be predominantly in the vanadyl, Viv, form. Both extracellular vanadium(V) and intracellular vanadium(IV) will be bound to bi- or tridentate ligands if at all. If oxidation-reduction processes involving vanadium are fast relative to transmembrane transport, the transmembrane potential will not be coupled to the Vv/Viv Nernstian potential.

Calorimetry↗
PubMed2003

Continuous analysis of dissolved gaseous mercury in freshwater lakes.

The concentration of dissolved gaseous mercury (DGM) in freshwaters changes more quickly than the 40-min processing time of current analytical methods. A new method for continuous field analysis of DGM was developed using a Tekran 2537A to achieve a DGM analysis time of 5 min. Samples were concurrently analyzed for temperature, oxygen, conductivity, pH, and oxidation-reduction potential using a Hydrolab. The detection limit for DGM ranged between 5 and 20 fmolL(-1) with 99% removal efficiency. Control experiments showed that there was no interference due to methyl mercury, which is present in similar concentrations to DGM. Controlled experiments comparing continuous DGM analysis with discrete DGM analysis showed that the results are not significantly affected by typical variations in water temperature (4-30 degrees C), oxidation-reduction potential (135-355 mV), dissolved organic carbon (4.5-10.5 mgL(-1)), or pH (3.5-7.8). The continuous analysis was within 4.5% of the discrete analysis when compared across 12 samples analyzed in triplicate. The field performance of this method was tested over two 48-h periods in two lakes in Kejimkujik Park, Nova Scotia where over 1000 data points were collected.

Environmental Monitoring↗
PubMed1980

Detection of cytochrome b+50 in membranes of Rhodospirillum rubrum isolated from aerobically and phototrophically grown cells.

1. Dark equilibrium potentiometric titrations were conducted on membranes purified from Rhodospirillum rubrum in an effort to identify b-type cytochrome components reported in other Rhodospirillaceae. In preparations from aerobically grown cells virtually devoid of bacteriochlorophyll a, three components were observed at 560-540 nm. Their oxidation-reduction midpoint potentials assigned by computer-assisted analysis were +195, +50 and -110 mV at pH 7.0; each of these fitted closely to theoretical single-electron equivalent curves. 2. In chromatophores from phototrophically grown carotenoidless mutant G-9, three components were also observed with E0' +190, +50 and -90mV. 3. The alpha-band of the +50mV component exhibited an absorption maximum near 560nm in difference spectra obtained at fixed oxidation-reduction potentials. 4. This component could be demonstrated most readily in purified membrane preparations and may have been obscured in previous studies by residual cytochrome c'. 5. This is the first definitive report of cytochrome b+50 in membranes from Rs. rubrum and aligns this bacterium with other Rhodospirillaceae in which this component functions in light-driven cyclic electron flow.

Aerobiosis↗
PubMed2004

The HP-1 maquette: from an apoprotein structure to a structured hemoprotein designed to promote redox-coupled proton exchange.

Synthetic heme-binding four-alpha-helix bundles show promise as working model systems, maquettes, for understanding heme cofactor-protein assembly and function in oxidoreductases. Despite successful inclusion of several key functional elements of natural proteins into a family of heme protein maquettes, the lack of 3D structures, due principally to conformational heterogeneity, has prevented them from achieving their full potential. We report here the design and synthesis of HP-1, a disulfide-bridged two-alpha-helix peptide that self-assembles to form an antiparallel twofold symmetric diheme four-alpha-helix bundle protein with a stable conformation on the NMR time-scale. The HP-1 design strategy began with the x-ray crystal structure of the apomaquette L31M, an apomaquette derived from the structurally heterogeneous tetraheme-binding H10H24 prototype. L31M was functionally redesigned to accommodate two hemes ligated to histidines and to retain the strong coupling of heme oxidation-reduction to glutamate acid-base transitions and proton exchange that was characterized in molten globule predecessors. Heme insertion was modeled with angular constraints statistically derived from natural proteins, and the pattern of hydrophobic and hydrophilic residues on each helix was then altered to account for this large structural reorganization. The transition to structured holomaquette involved the alteration of 6 of 31 residues in each of the four identical helices and, unlike our earlier efforts, required no design intermediates. Oxidation-reduction of both hemes displays an unusually low midpoint potential (-248 mV vs. normal hydrogen electrode at pH 9.0), which is strongly coupled to proton binding, as designed.

Amino Acid Sequence↗
PubMed2004

[Preparation and feasibility of superparamagnetic dextran iron oxide nanoparticles as gene carrier].

BACKGROUND & OBJECTIVE: Application of magnetic nano- particles as gene carrier in gene therapy of tumor has developed quickly. To obtain a new type non-viral gene introduction and therapy system,which is convenient,and can drive target gene to express highly and stably,this study was designed to explore the preparation of superparamagnetic dextran iron oxide nanoparticles(SDION),and the feasibility of SDION used as gene carrier in vitro. METHODS: SDION were prepared by chemical co-precipitation,separated by gel filtration chromatography on Sephacryl S-300HR,and centrifugation techniques,characterized by transmission electron microscopy,laser scattering system,and vibrating sample magnetometer signal processor. The green fluorescent protein-C2 (GFP-C2) plasmid was used as target gene. SDION-GFP- C2 compounds were synthesized by oxidation-reduction reaction. The connection rate of SDION and GFP-C2 was analyzed by agarose electrophoresis,and evaluated by measuring concentration of GFP in the supernatant after centrifugation. Liposome transfection was used as control,the efficiencies of SDION and liposome in transferring GFP gene into human bladder cancer BIU-87 cells were evaluated under fluorescence microscope in vitro. RESULTS: The diameter of SDION ranged from 3 nm to 8 nm, the effective diameter was 59.2 nm, and the saturation magnetization was 0.23 emu/g. After oxidized by sodium periodate of 10 mmol/L,and deoxidized by sodium hydride boron of 0.5 mol/L, SDION could connect with GFP in maximum degree,the transfection efficiency of SDION as gene carrier was about 45%, even higher than that of liposome (about 30%). CONCLUSION: SDION could connect with GFP plasmid by oxidation- reduction reaction,and success to transfer GFP gene into human bladder cancer BIU-87 cells in vitro.

Dextrans↗
PubMed1982

Characteristics of microsomal reduction of benzo[a]pyrene 4,5-oxide.

NADPH-reduction of benzo[a]pyrene 4,5-oxide (BP-4,5-oxide) to BP required four components from rat liver: cytochrome P-450, NADPH cytochrome P-450 reductase, phosphatidylcholine and a soluble, heat-sensitive factor which was present in 105 000 X g supernatant and was also released from microsomes by sonication. The requirement for this factor contrasts with recently reported results from Sugiura et al. (Cancer Res., 40 (1980) 2910). Oxide-reduction was 40 times faster under anaerobic conditions, but oxygen did not affect the stimulation factor. This stimulation was highest (X15) at low concentrations of microsomal protein (less than 0.1 mg/ml) and was almost absent at high concentrations of microsomal protein (greater than 1 mg/ml). Oxide-reduction activity was proportional to microsomal protein concentration in the presence of added 105 000 X g supernatant, but for microsomes alone (greater than 0.1 mg/ml) exhibited a parallel plot with an intercept at 0.08 mg/ml microsomal protein. Stimulation was highest at high concentrations of BP-4,5-oxide and a linear plot of V-1 vs. [BP-4,5-oxide]-1 was only obtained in the presence of 105 000 X g supernatant (Km = 3 microM, Vmax = 3.3 nmol/mg/min). Microsomal hydration of BP-4,5-oxide (inhibited in reductase assays) was unaffected by 105 000 X g supernatant, suggesting that stimulation of oxide-reduction did not derive from solubilization of BP-4,5-oxide. Stimulation was observed in the initial rate of reaction and was independent of incubation time. Inhibition of lipid peroxidation, removal of peroxides and deoxygenation were all excluded as explanations of the stimulatory effect.

Anaerobiosis↗