On the stoichiometry of the oxidase and monooxygenase reactions catalyzed by liver microsomal cytochrome P-450. Products of oxygen reduction

This laboratory has recently reported that, in a reconstituted enzyme system containing alcohol-induced isozyme 3a of liver microsomal cytochrome P-450, the sum of acetaldehyde generated by the monooxygenation of ethanol and of hydrogen peroxide produced by the NADPH oxidase activity is inadequate to account for the O2 and NADPH consumed. Studies on the stoichiometry have revealed the occurrence of an additional reaction involving an overall 4-electron transfer to molecular oxygen which is presumed to yield water: O2 + 2 NADPH + 2H+----2 H2O + 2 NADP+. The occurrence of a peroxidase reaction in which free H2O2 is reduced to water by NADPH was ruled out. When the 4-electron oxidase activity is taken into account, measurements of NADPH oxidation and O2 consumption are in accord with the amounts of products formed in the presence of various P-450 isozymes, either in the absence or presence of typical substrates, including those which undergo hydroxylation, N- or O-demethylation, or oxidation of hydroxymethyl to aldehyde groups. Of the substrates examined, some had no effect on the oxidase reaction yielding hydrogen peroxide or the 4-electron oxidase reaction, some were inhibitory, and some were stimulatory, but the same substrate did not necessarily have the same effect on the two reactions.

Lucigenin-dependent chemiluminescence as a new assay for NAD(P)H-oxidase activity in particulate fractions of human polymorphonuclear leukocytes

The enzyme responsible for the respiratory burst in human neutrophils is an oxidase that catalyzes the reduction of oxygen to superoxide anion (O-2). Superoxide anion production may be measured by chemiluminescence (CL) in the presence of lucigenin (10,10'-dimethyl-9,9'- biacridinium dinitrate). We established an assay of the oxidase, by measuring the CL of particulate fractions of PMN in the presence of lucigenin . This CL required the addition of NAD(P)H and was very low in fractions of resting cells. In particulate fractions of PMNs stimulated with PMA selectively, the NADPH-dependent CL was found to be increased. CL was linear with protein concentrations up to 100 micrograms and was shown to be at least 10 times more sensitive for the detection of O-2 than the assay based on the spectrophotometric determination of superoxide mediated cytochrome c reduction. CL was abolished by inactivating the enzyme at 56 degrees C.

The NADPH oxidase of human polymorphonuclear leukocytes. Evidence for regulation by multiple signals

Activation of the membrane-bound NADPH oxidase in human polymorphonuclear leukocytes can be triggered by chemoattractants, the tumor promoter phorbol myristate acetate or the calcium ionophore A23187. We have shown previously that these stimuli have markedly different temporal patterns of oxidase activation (McPhail, L. C., and Snyderman, R. (1983) J. Clin. Invest. 72, 192-200), suggesting that each follows, at least in part, a unique transductional pathway. We now report that if leukocytes were sequentially exposed to any of several combinations of heterologous stimuli, the pattern of activation by the second stimulus was strikingly altered, resulting in a more rapid rate and enhanced level of oxidase activation by the second stimulus. This suggests that exposure of cells to the first stimulus (priming) had influenced an intermediate also used by the second stimulus. The signal for priming could be clearly distinguished from the signal causing oxidase activation by the dose-response curves for each, as well as by the use of several pharmacologic agents. In addition, if leukocytes were given sequential doses of homologous stimuli, either partial (phorbol myristate acetate) or full (N-formyl-methionyl-leucyl -phenylalanine and A23187) desensitization of oxidase activation was observed. These results demonstrate that these stimuli share a common intermediate in the pathway of oxidase activation. Moreover, the data indicate that NADPH oxidase activation is regulated by at least three distinct signals: signal 1 (priming), signal 2 (activation), and signal 3 (inactivation). It is likely that more than one intracellular messenger exerts a modulating influence on NADPH oxidase activity and that its regulation involves the interplay between several cellular control proteins.

NADPH oxidase of neutrophils forms superoxide anion but does not reduce cytochrome c and dichlorophenolindophenol

Superoxide (O-2) production by partially purified NADPH oxidase from guinea pig neutrophils was markedly increased when the cells were activated by exposure to phorbol-myristate acetate. On the contrary, NADPH-dependent cytochrome c and 2,6-dichlorophenolindophenol (DCIP) reductase activities in preparations from resting and activated neutrophils were similar. The apparent Km values for NADH and NADPH of the reductase activities were different from those of the O-2 producing enzyme. The electron acceptors did not inhibit the oxygen consumption by NADPH oxidase in the presence of superoxide dismutase. Even in anaerobiosis the oxidase failed to reduce cytochrome c and DCIP. These results suggest that NAD(P)H-dependent dye reductase activities are not involved in the electron transport system responsible for the O-2 production by neutrophils.

Development of the superoxide-generating system during differentiation of the HL-60 human promyelocytic leukemia cell line

Utilizing the induced differentiation of HL-60 promyelocytic leukemia cells as a model of myeloid maturation, we examined the development of the superoxide-generating system, focusing on NADPH oxidase activity, membrane depolarization, and cytochrome b content. NADPH oxidase activity, measured as NADPH-dependent superoxide production, increased with both spontaneous and N,N-dimethylformamide-induced differentiation. Activity in particulate fractions from induced HL-60 cells and human peripheral blood polymorphonuclear leukocytes was proportional to their relative rates of superoxide production, but activity from uninduced cells was surprisingly high: one-third that from induced cells, despite only 7% their rate of superoxide generation. NADPH oxidase activities in phagocytic vesicles from induced HL-60 cells and polymorphonuclear leukocytes were equal, indicating the equivalence of the enzyme system in active portions of their cell membranes. Separation by centrifugal elutriation of the HL-60 cell population into fractions of varying maturity confirmed the relationship of NADPH oxidase activity to advancing differentiation in both dimethylformamide-induced and spontaneously maturing cells. Membrane potential change, an early event related to activation of the oxidase, was followed by 3,3'-dipropylthiodicarbocyanine dye fluorescence. The depolarization response increased dramatically in both magnitude and initial rate of change during differentiation. The cells' cytochrome b content increased 3-fold with induction of differentiation, in proportion to the change in NADPH oxidase activity.

NADPH-dependent reduction of ubiquinone-1 associated with the superoxide-forming oxidase of pig polymorphonuclear leucocytes

NADPH-dependent ubiquinone-1 reductase activity was present in the phagocytic vesicles of pig polymorphonuclear leucocytes. The apparent Km-value of the reductase for NADPH was 29 microM which is similar to that of the NADPH-dependent superoxide formation. Increase of the quinone-reductase activity by increasing the concentrations of ubiquinone-1 was associated with the decrease of the superoxide forming activity, the rate of the NADPH oxidation being constant independent of the quinone concentration. p-Chloromercuribenzoate inhibited both superoxide formation and reduction of the quinone, whereas low concentrations of cetyltrimethylammonium bromide which inhibit the superoxide formation did not inhibit the reduction of the quinone. The reduction of 2,6-dichlorophenolindophenol which has been shown not to be inhibited by both inhibitors. The quinone-reductase activity could be extracted with a mixture of deoxycholate and Tween 20 which extracts the superoxide forming activity. The observations indicate that a region of the superoxide-forming NADPH oxidase between a mercurial-sensitive site and a site sensitive to the cationic detergent is responsible for the reduction of ubiquinone.

Terminal oxidases of Escherichia coli aerobic respiratory chain. II. Purification and properties of cytochrome b558-d complex from cells grown with limited oxygen and evidence of branched electron-carrying systems

Cytochrome b558-d complex, a terminal oxidase in the respiratory chain of Escherichia coli K12 grown under the condition of limited oxygen, was purified to near homogeneity. The purified oxidase complex is composed of equimolar amounts of two polypeptides, with Mr = 26,000 and 51,000, determined with gel electrophoresis in the presence of sodium dodecyl sulfate. It contains 12.3 nmol of protoheme, 9.54 nmol of cytochrome d, and 26.6 nmol of iron/mg of protein. The enzyme is a "cytochrome bd-type oxidase," which shows absorption peaks at 558 and 624 nm in the difference spectrum at 77 K. This oxidase combines with CO, and the Soret region of the CO difference spectrum at room temperature has a peak at 420 nm and troughs at 430 and 442 nm. The oxidation-reduction potentials of cytochrome b558 and cytochrome d at pH 7.4 were estimated to be +10 mV and +240 mV, respectively. The cytochrome b558-d complex catalyzes the oxidation of ubiquinol-1, menadiol, and ascorbate in the presence of N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride. This oxidase activity was inhibited by the respiratory inhibitors piericidin A, KCN, and NaN3, but the cytochrome b558-d complex was less sensitive to the inhibitors than the cytochrome b562-o complex. The Km values for oxygen of purified cytochrome b558-d complex and cytochrome b562-o complex were determined to be 0.38 and 2.9 microM, respectively. Formation of a membrane potential by the reconstituted cytochrome b558-d complex in liposomes was observed with the fluorescent dye 3,3'-dipropylthiocarbocyanine iodide on addition of ubiquinol-1. This is the first indication that there is a coupling site in the terminal oxidase, which contains cytochrome d. Steady state kinetics of cytochromes in the membrane showed that these oxidase complexes branch at the site of ubiquinone-8 in the respiratory chain. From these and previous results, branched electron-carrying systems of the E. coli respiratory chain are proposed.

Bactericidal mechanisms of the human neutrophil. An integrated biochemical and morphological model

The bactericidal activity of the human neutrophil is dependent on a coordinated series of events by which the bacteria become confined to a vacuole. Fusion of the azurophil and specific granules with the phagocytic vacuole results in secretion of BPI, the primary oxygen independent bactericidal protein, and of myeloperoxidase into the phagolysosome. Simultaneously, an electron transport chain, the NADPH oxidase, is activated in the membrane of the phagolysosome, resulting in generation of H2O2, which together with myeloperoxidase and Cl- forms a highly bactericidal agent. Digestion of the killed bacteria is subsequently effectuated by proteases and lipases of the neutrophil granules. The neutrophil thus has several highly efficient bactericidal systems that overlap to a certain degree, thereby giving the neutrophil an overcapacity to kill. This is appreciated in the defence against microorganisms, but is increasingly being recognized as a cause of perturbation of serum protease anti-protease homeostasis that may cause major tissue destruction. The recent achievements in the understanding of neutrophil function will hopefully permit better control to be exerted over this potent cell.

Deficient flavoprotein component of the NADPH-dependent O2-.-generating oxidase in the neutrophils from three male patients with chronic granulomatous disease

The NADPH-dependent O2-.-generating oxidase in subcellular fractions from the neutrophils of three male patients with chronic granulomatous disease was compared with the corresponding preparations from normal neutrophils. The oxidase from normal neutrophils contained flavin adenine dinucleotide in an approximately 0.9:1 molar ratio with cytochrome b559. Each of the three chronic granulomatous disease patients had decreased amounts of the flavoprotein component of the oxidase fraction. The oxidase from two chronic granulomatous disease patients had undetectable amounts of cytochrome b559 whereas the third patient had a normal content of cytochrome b559, which was spectrally indistinguishable from the normal. The intrinsic cytochrome b559 in the oxidase fraction from stimulated neutrophils of the latter chronic granulomatous disease patient was not reduced by NADPH under anaerobic conditions, in distinction with the previously reported reduction of the normal cytochrome b559 under identical conditions. We conclude that the flavoprotein component of the oxidase may mediate transfer of electrons from NADPH to the cytochrome b559 in normal neutrophils, and that deficiency of this flavoprotein is associated with the chronic granulomatous disease phenotype in the three patients studied.

[Current theories of phagocytosis and methodological problems in the study of phagocytosis defects in diabetics]

The process of phagocytosis on bacteria is described: recognition of the bacterium by C3b- and Fc-receptors and possibly lektin-like substances on PMN surfaces; ingestion by an actin-myosin interaction in a local Ca++ gradient; simultaneous activation of a NADPH-oxidase and oxidative attack of the bacterial membrane. Special aspects: opsonization, dependence of the rate of phagocytosis on day-time, conditions of diabetics.

Catalytic properties of the resolved flavoprotein and cytochrome B components of the NADPH dependent O2- . generating oxidase from human neutrophils

The resolved flavoprotein and cytochrome b559 components of the NADPH dependent O2- . generating oxidase from human neutrophils were the subject of further study. The resolved flavoprotein, depleted of cytochrome b559, was reduced by NADPH under anaerobic conditions and reoxidized by oxygen. NADPH dependent O2- . generation by the resolved flavoprotein fraction was not detectable, however it was competent in the transfer of electrons from NADPH to artificial electron acceptors. The resolved cytochrome b559, depleted of flavoprotein, demonstrated no measureable NADPH dependent O2- . generating activity and was not reduced by NADPH under anaerobic conditions. The dithionite reduced form of the resolved cytochrome b559 was rapidly oxidized by oxygen, as was the cytochrome b559 in the intact oxidase.

Reversible blockade of the respiratory burst in human neutrophils by a cleavable cross-linking agent

Human neutrophils treated with low concentrations of the homobifunctional cross-linking reagents disuccinimidyl suberate and dithiobis(succinimidylpropionate) failed to generate superoxide in response to any of several stimuli, including phorbol myristate acetate, fMet-Leu-Phe, A23187, fluoride, and opsonized zymosan. The cross-linking reagent interfered with the activation of NADPH oxidase, but not with its activity. Cells treated with succinimidyl butyrate, a monovalent analog of the cross-linkers, underwent a normal respiratory burst. Cross-linking also inhibited degranulation, phagocytosis, and fluorescence responses of potential-sensitive dyes but had little effect on lactate production, sugar transport, the binding of fMet-Leu-Phe, or the activity of various enzymes in the cross-linked neutrophils. Most of the cellular functions inhibited through the reaction of neutrophils with the cleavable cross-linker dithiobis(succinimidylpropionate) could be restored by reduction of the disulfide bonds of the cell-bound cross-linker with dithiothreitol.

Subcellular localization of the human neutrophil NADPH oxidase. b-Cytochrome and associated flavoprotein

Human neutrophils were fractionated by nitrogen cavitation and Percoll density centrifugation, and the subcellular localization of FAD-flavoprotein, b-cytochrome, NADH-cytochrome b5 reductase, and NADPH-dependent cytochrome c reductase were determined in normal cells, cells from two patients with chronic granulomatous disease (CGD), and normal cells that had been stimulated with phorbol myristate acetate. In normal cells, a FAD-flavoprotein is found in a 1:2 molar ratio, with cytochrome b in the fractions containing the specific granules. Triton X-114 phase distribution indicates that the b-cytochrome but not the b-cytochrome-associated flavoprotein is an integral membrane protein. 80% of this flavoprotein, as well as all the b-cytochrome, was absent in these fractions from 2 CGD patients, although these patients had normal quantities of FAD in the fractions containing plasma membranes and cytosol. During stimulation the b-cytochrome-associated flavoprotein of the granules translocates with the b-cytochrome to the plasma membrane where NADPH oxidase is localized. Definition of the role of these NADPH oxidase constituents may provide a molecular description of the normal neutrophil respiratory burst and the molecular defect(s) in CGD.

Rat liver microsomal cholesterol biosynthesis and drug oxidase activity are affected by chromium ions (Cr3+) in vitro

Chromium ions (Cr3+)evoked a biphasic curve of changes of rat liver microsomal cholesterol biosynthesis using [14C]acetate and/or [14C]mevalonate as precursors. While for the lower range of Cr3+ concentrations the rate of cholesterol biosynthesis rises, at concentrations above 8 X 10(-6) M they evoke a decrease in the cholesterol biosynthesis, up to 50% down on its control value at a concentration of 8 X 10(-4) M. Differences were more pronounced when using [14C]mevalonate instead of [14C]acetate as precursor. The activity of the microsomal enzyme biphenyl-4-hydroxylase showed an equally intense rise to that of cholesterol biosynthesis up to a 8 X 10(-6) M Cr3+ concentration. Above this concentration, however, the activity of the enzyme starts to drop. NADPH-cytochrome c reductase and NADPH-oxidase were decreased at all Cr3+ concentrations used, which cover a 100-fold range. Lineweaver-Burk plots of the cytoplasmic glucose-6-phosphate dehydrogenase demonstrated an uncompetitive mechanism of inhibition by Cr3+ ions. The results are discussed in terms of the possible significance of the Cr3+ concentration-dependent effects on cholesterol biosynthesis, with the observed atherosclerosis in Cr-deficient humans.

Ultrastructural localization of NADPH-oxidase activity in murine peritoneal macrophages during phagocytosis of Brucella. Correlation with the production of superoxide anions

The localization of the enzyme NADPH oxidase in mouse peritoneal macrophages unstimulated or after phagocytosis of Brucella suis was investigated by electron microscopy in normal mice and mice immunized against B. suis. The enzyme was clearly visualized on mitochondrial cristae, smooth endoplasmic reticulum, and the plasma membrane; its activity correlated mainly with the state of the endoplasmic reticulum which itself reflected macrophage activation. The enzyme turnover appeared to be accelerated after phagocytosis; the phagosome membrane was seldom stained by the enzyme reaction. These macrophages were also examined for the production of superoxide anions in vitro, either unstimulated or after phagocytosis. Phagocytosis increased the production of superoxide anions, especially in immunized animals. These results are discussed with regard to the role that the products of oxidative metabolism play in the inactivation of bacteria by phagocytic cells.

Changes in protein phosphorylation in guinea pig polymorphonuclear leukocytes by treatment with membrane-perturbing agents which stimulate superoxide anion production

Phosphorylation of proteins was examined in guinea pig polymorphonuclear leukocytes in relation to the effects of membrane-perturbing agents, which stimulate superoxide anion production, and their inhibitors. The phosphorylation was detected by 32P autoradiography after separation by two-dimensional electrophoresis of proteins phosphorylated in 32P-preloaded cells. Though phosphorylation of various proteins was stimulated by each of the membrane-perturbing agents, the stimulation was especially marked in six proteins. Phorbol myristate acetate and digitonin enhanced the phosphorylation of the six proteins, while myristate and concanavalin A increased the phosphorylation of five and three proteins, respectively, out of the six proteins. p-Bromophenacyl bromide, an inhibitor of phospholipase A2, inhibited the stimulatory effect of phorbol myristate acetate on both superoxide anion production and protein phosphorylation. Trifluoperazine, a calmodulin inhibitor, also inhibited the effect of phorbol myristate acetate on both, except for an increase in the phosphorylation of one out of the six proteins. alpha-Methylmannoside, an inhibitor of concanavalin A binding, inhibited the stimulation of the phosphorylation of the three proteins by concanavalin A. The results indicate that the activation of superoxide anion production by the membrane-perturbing agents in guinea pig polymorphonuclear leukocytes is accompanied by the phosphorylation of, at least some of, these six proteins.

Triphenyltin chloride inhibits superoxide production by human neutrophils stimulated with a surface active agent

Treatment of human neutrophils with triphenyltin chloride (TPTCl)-inhibited superoxide (O-2) production stimulated with phorbol myristate acetate (PMA). TPTCl was more potent as inhibitor of O-2 production than other phenyltin compounds. The O-2 production by the xanthine oxidase-acetaldehyde system was not inhibited by TPTCl. This finding indicates that TPTCl does not itself react with O-2. Furthermore, TPTCl did not influence the isolated NADPH oxidase at all, though O-2 production of neutrophils stimulated with PMA in the presence of TPTCl was inhibited. These results indicate that TPTCl inhibits the activation process of the O-2 generating system.

Effect of maleimide derivatives, sulfhydryl reagents, on stimulation of neutrophil superoxide anion generation with concanavalin A

Using maleimide derivatives with relatively rare side reactions, their effect on stimulation of O-2 production by guinea-pig neutrophils with Con A was studied. Showdomycin, a very slowly penetrating agent, did not affect O-2 production whereas NEM, a rapidly penetrating agent, markedly inhibited O-2 production without interference with binding of Con A to cells. Particulate fractions from neutrophils stimulated with Con A showed markedly increased NADPH-dependent O-2 production compared with fractions from unstimulated cells. Treatment of neutrophils with NEM before exposure to Con A inhibited the enhancement of NADPH-dependent O-2 production of particulate fractions by Con A. However, particulate fractions from Con A-stimulated and unstimulated cells hardly exhibited reduced NADPH oxidase activity after direct exposure to NEM. Treatment of neutrophils with NEM after activation by Con A had no effect on NADPH-dependent O-2 production of particulate fractions. These results indicate that NEM inhibits the activation process of the O-2-generating enzyme, probably NADPH oxidase with Con A.

NIH conference. Recent advances in chronic granulomatous disease

Chronic granulomatous disease represents a group of disorders of phagocytic cell oxidative metabolism involving recurrent infections with catalase-positive microorganisms and chronic inflammation. Genetic heterogeneity and phagocyte abnormalities, including enzyme deficiencies, abnormal elicited membrane potential changes, abnormal acidification of the phagocytic vacuole, and deficiencies of an electron transport cascade, have been associated with its pathogenesis. In addition, recently we have shown abnormal neutrophil C3b-receptor expression, antibody-dependent cellular cytotoxicity, and abnormal microtubule metabolism (tyrosinolation of the alpha-chain of tubulin). Fourteen patients with the disease who were followed at the National Institutes of Health had life-threatening infections, on average, once every 9.6 months. In most of the 119 febrile episodes seen in these patients, no infectious agent was found. Retrospective studies indicated that prophylactic antibiotic therapy, particularly with trimethoprim-sulfamethoxazole, significantly prolonged disease-free intervals to greater than 40 months (p less than 0.05). In serious, life-threatening infections, leukocyte transfusions have been used in therapy. Transfused leukocytes localize and persist at infectious sites, and the clinical efficacy of leukocyte transfusions has been suggested.

Butylated hydroxyanisole-stimulated NADPH oxidase activity in rat liver microsomal fractions

NADPH-dependent oxygen utilization by liver microsomal fractions was stimulated by the addition of increasing concentrations of butylated hydroxyanisole concomitant with the inhibition of benzphetamine N-demethylase activity. The apparent conversion of monooxygenase activity to an oxidase-like activity in the presence of the antioxidant was correlated with the partial recovery of the reducing equivalents from NADPH in the form of increased hydrogen peroxide production. The progress curve of liver microsomal NADPH oxidase activity in the presence of butylated hydroxyanisole displayed a lag phase indicative of the formation of a metabolite capable of uncoupling the monooxygenase activity. Ethyl acetate extracts of microsomal reaction mixtures obtained in the presence of butylated hydroxyanisole, oxygen, and NADPH stimulated the NADPH oxidase activity of either liver microsomes or purified NADPH-cytochrome c (P-450) reductase. Using high performance liquid chromatography, gas chromatography, and mass spectrometry techniques, two metabolites of butylated hydroxyanisole, namely t-butylhydroquinone and t-butylquinone, were identified. The quinone metabolite and/or its 1-electron reduction product interact with the flavoprotein reductase to directly link the enzyme to the reduction of oxygen which results in an inhibition of the catalytic activity of the cytochrome P-450-dependent monooxygenase.

Decreased bactericidal function and impaired respiratory burst in lung macrophages after sustained in vitro hyperoxia

Lung macrophages (LM) play a crucial role in pulmonary bacterial defense. High inspired oxygen concentrations are used in a variety of diseases and "oxygen toxicity" could impair antibacterial function. We therefore examined the effect of sustained in vitro hyperoxia on LM bactericidal function, and on generation of two bactericidal oxygen metabolites. The LM were cultivated under aerobic (PO2 approximately 140 mmHg) or hyperoxic (PO2 approximately 630 mmHg) conditions for 48 h, and then incubated with Staphylococcus aureus labeled with 3H thymidine for 30 min. Incubated monolayers were processed for measurement of total bacterial uptake and for number of viable intracellular bacteria. Superoxide anion (O2-) and hydrogen peroxide (H2O2) generation was determined in similarly cultivated cells stimulated with opsonized zymosan. The results indicate that the bacterial killing capacity of oxygen-cultivated LM is significantly decreased (p less than 0.001). In addition, a significant (p less than 0.001) decrease in generation of O2- and H2O2 was noted after exposure to high oxygen tensions. The data suggest that decreased bactericidal function after sustained hyperoxia may be due to an impairment of a specific bactericidal mechanism, i.e., an impaired "respiratory burst."

Chronic granulomatous disease: a syndrome of phagocyte oxidase deficiencies

Chronic granulomatous disease (CGD) is an inherited disorder of host defense due to the inability of the phagocyte to generate toxic oxygen metabolites upon appropriate stimulation. The disorder is heterogeneous even within the confines of a defective respiratory burst oxidase function, and may arise from a biochemical lesion at either the receptor, the activating pathways or the enzyme level. The identification of defects in plasma membrane depolarization, missing cytochrome and abnormal enzymatic function has yielded new insights into the pathophysiologic basis of CGD. A classification of this syndrome based on more precise biochemical criteria is proposed, which defines the disease as distinct from other associated enzymopathies with similar pathology and emphasizes the metabolic basis of the pathophysiologic defect in phagocyte function. Review of the clinical manifestations, pathogenic organisms and natural course of the disease, emphasizes the critical role of the oxidative metabolism of the normal neutrophil and offers a perspective on oxygen free radical biochemistry in the inflammatory response.

Effect of guanosine nucleotides on the respiratory burst oxidase from human neutrophils

The respiratory burst is a series of metabolic events which result in the production of microbicidal oxidants by phagocytes. The enzyme responsible for the respiratory burst is a membrane-bound oxidase which catalyzes the production of O-2 by the NADPH-dependent reduction of oxygen. Activity of this oxidase is diminished by a variety of guanosine-containing nucleotides. The decrease in activity caused by GTP, the most potent of these, occurs rapidly and is not solely dependent on hydrolysis of terminal phosphate groups. GTP appears to diminish oxidase activity through both inhibition and inactivation. GTP-mediated inhibition is kinetically mixed with respect to NADPH.

Activation of guinea pig polymorphonuclear leukocytes with soluble stimulators leads to nonrandom distribution of NADPH oxidase in the plasma membrane

Guinea pig polymorphonuclear leukocytes (PMN) were briefly activated with soluble stimulators such as sodium myristate (SM) or phorbol myristate acetate (PMA) and then disrupted by the nitrogen cavitation method to study the subcellular distribution of NADPH oxidase, which is responsible for O2 - generation. Fc-receptor and 5'-nucleotidase activities were measured as plasma membrane markers. 1) The homogenate was first fractionated by differential centrifugation. The O2- -generating activity of PMN activated either by SM or PMA was recovered in a 2 X 10(4) g pellet which contained a large amount of granules and about 50% of the plasma membrane markers, but not in a 1 X 10(5) g pellet which consisted of plasma membranes and few granules. 2) Further separation of the 2 X 10(4) g pellet from PMA-activated PMN was attempted by an iso-osmotic Percoll density gradient centrifugation. The O2- -generating activity was recovered in light fractions in which plasma membrane markers were found, but neither in specific nor in azurophil granules. The 1 X 10(5) g pellet showed a similar distribution of the plasma membrane markers to that of the 2 X 10(4) g pellet, except that the peak of the O2- -generating activity was much smaller on an identical density gradient. The results showed that NADPH oxidase is located in the plasma membranes precipitated by centrifugation at 2 X 10(4) X g but not in the ones precipitated at 1 X 10(5) X g. The results suggest that the plasma membrane of activated PMN has a mosaic distribution of NADPH oxidase.

Essential requirement of magnesium ion for optimal activity of the NADPH oxidase of guinea pig polymorphonuclear leukocytes

The NADPH-dependent O2-(H2O2)-forming oxidase-rich plasma membranes were purified from myristate (MA)-activated polymorphonuclear leukocytes using a Percoll-density gradient method. The specific activity of the enzyme in the plasma membrane fraction was twelve times higher than that in the cells. Studies on the effect of divalent cations and chelators on the O2- and H2O2 generating activity of the oxidase showed that Mg2+, but not Ca2+, enhanced the activity significantly. Zn2+, on the other hand, was slightly inhibitory to the oxidase activity. EDTA markedly inhibited the oxidase activity whereas EGTA enhanced it. The optimal oxidase activity was seen in the presence of mumolar concentrations of Mg2+ and reached a maximum at Mg2+ concentrations of 40-50 microM. The addition of Mg2+ resulted in a decrease in the apparent Km of the oxidase for NADPH from 40 microM to 25 microM and an increase in apparent Vmax by 1.5 times. These results suggest that Mg2+ enhances both NADPH binding and catalytic activities of the oxidase.

Activation of mouse peritoneal macrophages by lipopolysaccharide alters the kinetic parameters of the superoxide-producing NADPH oxidase

Macrophages activated by infection or elicited by injection of lipopolysaccharide (LPS), when stimulated with phorbol myristate acetate, release greater amounts of superoxide anion (O-2) than do normal resident macrophages. This enhanced production of O-2 and of other oxygen metabolites derived from O-2 is responsible, at least in part, for the enhanced microbicidal activity of these cells. To investigate the molecular basis for the enhanced oxygen metabolite response, the kinetic parameters of the enzyme responsible for NADPH-dependent production of O-2 (NADPH oxidase) were compared in LPS-elicited and resident mouse peritoneal macrophages. Resident and LPS-elicited macrophages were stimulated with phorbol myristate acetate, disrupted by sonication, assayed for their content of NADPH, and fractionated by centrifugation. The distribution of NADPH oxidase activity among the fractions was similar in both types of macrophage. A membrane-rich 27,000 X g pellet, which had the highest specific activity for the oxidase among the various fractions, was utilized to study the kinetic parameters of the oxidase from normal and LPS macrophages. The oxidase from LPS-elicited macrophages displayed a higher Vmax and a lower Km for NADPH than did the oxidase from normal cells. LPS-elicited cells also had a higher intracellular concentration of NADPH than did normal cells. The altered Km and Vmax, combined with the higher concentration of NADPH, resulted in a 2.2- to 3.5-fold increase in the calculated velocity of the oxidase from LPS-elicited macrophages compared with that from resident macrophages. These results suggest that the enhanced oxygen metabolite response of activated macrophages is due, in part, to modification of the enzyme responsible for the production of O-2.

The purification and characterization of the cytochrome d terminal oxidase complex of the Escherichia coli aerobic respiratory chain

The aerobic respiratory chain of Escherichia coli is branched. In aerobically grown cells harvested in midexponential phase, a respiratory chain containing only b-type cytochromes is predominant. This chain contains a terminal oxidase which is a b-type cytochrome, referred to as cytochrome o. However, when the bacteria are grown under conditions of oxygen limitation, additional components of the respiratory chain are induced, as evidenced by the appearance of new spectroscopic species. These include a new b-type cytochrome, cytochrome b558, as well as cytochrome a1 and cytochrome d. In this paper, a purification protocol and the initial characterization of the terminal oxidase complex containing cytochrome d are reported. Solubilization of the membrane is effected by Zwittergent 3-12, and purification is accomplished by chromatography with DEAE-Sepharose CL-6B and hydroxyapatite. The complex contains cytochrome b558, a1, and d. Analysis by sodium dodecyl sulfate-polyacrylamide gels indicates that the complex contains only two types of polypeptides with the molecular weights estimated to be 57,000 and 43,000. The purified complex has oxidase activity in the presence of detergents, utilizing substrates including ubinquinol-1, N,N,N',N'-tetramethyl-p-phenylenediamine, and 2,3,5,6-tetramethyl-p-phenylenediamine. The cytochrome d complex contains protoheme IX and iron, but does not contain nonheme iron or copper. Approximately half of the cytochromes which are thought to participate in E. coli aerobic respiration are accounted for by this single complex. These results suggest that the E. coli aerobic respiratory chain is organized around a relatively small number of cytochrome-containing complexes.

Electrophoretic isolation of a membrane-bound NADPH oxidase from guinea-pig polymorphonuclear leukocytes

Electrophoretic isolation of a membrane-bound NADPH oxidase of guinea-pig polymorphonuclear leukocytes was attempted with the O2- -generating membranes of cells unstimulated or stimulated with C3b-zymosan or sodium dodecyl sulfate, and also with the phagosomes isolated from the phorbol myristate acetate-coated latex particle-phagocytosing cells. When these vesicles were subjected to discontinuous polyacrylamide gel electrophoresis in the presence of Triton X-100 and then assayed for NADPH-Nitroblue tetrazolium reducing activity, the activity was detected by the appearance of a single, blue band of the reduced dye on the gel, independent of the source of vesicles. In addition, the enzyme was able to generate O2- and its activity was significantly augmented with the homologous liver microsomal cytochrome b5. Its activity was heat-labile and inactivated by N-ethylmaleimide and p-chloromercuribenzene sulfonate. The enzyme, with an apparent molecular weight of 150 000, in the phagosomes was easily susceptible to limited proteolysis by trypsin and formed an active fragment with a molecular weight of 70 000, accompanying the loss of O2- -generating activity of the vesicles.

Identification of calcium-dependent proteolytic activity in human polymorphonuclear leukocytes

Calcium-dependent proteolytic activity has been identified in extracts of human polymorphonuclear leukocytes. The activity is most pronounced in the neutral pH range with a pH optimum of 7.3. Maximal activation of the protease occurs at a free calcium concentration of 190 microM; it is half maximal at 91 microM. This protease activity is strongly inhibited by aprotinin and phenylmethylsulfonyl fluoride (PMSF) and more weakly inhibited by antipain, leupeptin, and o-phenanthroline. The protease is not activated by calmodulin nor is it inhibited by the calmodulin antagonist trifluoperazine. Gel filtration suggests a molecular weight of 74,100 daltons.

The cytochrome b and flavin content and properties of the O2- -forming NADPH oxidase solubilized from activated neutrophils

NADPH-dependent O2- -generating activity was extracted and partially purified from guinea pig polymorphonuclear leukocytes. The most active preparation generated 202.8 nmol O2- min/min per mg protein. This activity was 30-fold higher than that of extracts from resting cells, indicating that the activated state of the oxidase was retained after solubilization. The solubilization and purification of the enzyme activity were followed by a parallel solubilization and purification of cytochrome b. Spectroscopic studies showed that solubilized cytochrome b has an Em of -245 mV and binds CO to about 30%. Cytochrome b was reduced by NADPH in anaerobiosis at a low rate and was rapidly reoxidized by air. A correlation was found between the inhibition of O2- formation caused by the SH reagent p-chloromercuribenzoate and the alterations induced by this compound on the Em of cytochrome b. These observations strongly support the participation of cytochrome b in the catalytic activity of the solubilized NADPH oxidase. The enzyme preparations contained FAD, which was found to be associated both with NADPH oxidase and with diaphorase activities. The fraction with the highest O2- forming activity contained FAD and cytochrome b in a ratio of about 0.5:1. The participation of FAD in the electron transport from NADPH to O2 is supported also by the inhibitory effect exerted by quinacrine on O2- formation.

The interactive effects of fluoride and N-formyl-L-methionyl-L-leucyl-L-phenylalanine on superoxide production and cAMP levels in human neutrophils

The kinetics of superoxide (O2-) production and intracellular cAMP levels were monitored in human neutrophils incubated in vitro with sodium fluoride and the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP). F- activation of both the O2- -generating system, NAD(P)H oxidase, and adenylate cyclase was characterized by a prolonged lag period of 8 to 10 min at 37 degrees C. Adenylate cyclase agonists or cAMP analogues which inhibited FMLP-induced O2- bursts did not affect O2- production of F- -activated cells. Prior treatment of cells with F- suppressed the short rapid burst elicited by FMLP but not the binding of the tripeptide. FMLP reciprocally decreased the lag period of the F- -induced burst by 40 to 50% and, in the case of cells incubated at temperatures below 37 degrees C, increased the rate of O2- production. A similar potentiating effect of FMLP on F- -induced elevation of intracellular cAMP levels was observed.

Activation of the respiratory burst enzyme in human polymorphonuclear leukocytes by chemoattractants and other soluble stimuli. Evidence that the same oxidase is activated by different transductional mechanisms

Chemoattractant-receptor coupling triggers several biologic responses in phagocytic cells including activation of the respiratory burst. Prior evidence in intact cells implied that stimulation of the respiratory burst by chemoattractants was by a mechanism different from other soluble agents suggesting the possibility that different oxidative enzymes were responsible. We now show that the chemoattractants N-formyl-methionyl-leucyl-phenylalanine and a split fragment of the fifth component of complement (C5a) stimulate an NADPH oxidase activity, measured in the 50,000-g particulate fraction from human polymorphonuclear leukocytes (PMN). Levels of oxidase activity stimulated by the chemoattractants were both time and dose dependent and required the presence of cytochalasin B during stimulation. In contrast, activation by two nonchemotactic stimuli, the ionophore A23187 and phorbol myristate acetate (PMA), did not require cytochalasin B. Temporal patterns of oxidase activation suggested that different stimuli follow different transductional pathways. Chemoattractant-mediated activation was immediate (no lag); peaked by 45 s and declined rapidly to approximately 50% of maximal by 2 min. In contrast, activation by A23187 or PMA had a 15-30-s lag and increased more slowly. Stimulation by A23187 peaked at 5 min, then declined. Stimulation by PMA plateaued at 20 min and did not decline by 90 min. Comparison of Km values for NADPH and NADH obtained by Lineweaver-Burk analysis of the oxidase activity stimulated by N-formyl-methionyl-leucyl-phenylalanine, A23187, and PMA suggested that the same enzyme was activated by all stimuli. Thus, chemoattractants and other soluble stimuli appear to activate the same respiratory burst enzyme in PMN but they utilize different transductional mechanisms and are regulated differently.

On the geometry of leukocyte NADPH-oxidase, a membrane flavoenzyme. Inferences from the structure of glutathione reductase

Using the structure of glutathione reductase as a model, we suggest the following topography for leukocyte NADPH-oxidase: The binding sites of NADPH and O2 are separated from each other by the flavin ring and are thus exposed to opposite sides of the plasma membrane. This model supports the concept that O-2 is formed at the membrane facing the extracellular or phagosomal space, respectively. The fate of the proton produced in the reaction NADPH + 2 O2 leads to NADP + 2 O-2 + H+ is also discussed in light of our model. NAD(P)H-oxidases possessing the topography of glutathione reductase may establish transmembrane proton gradients. Consequently our model suggests that leukocyte NADPH-oxidase produces not only the O-2 burst but also a proton burst.

Partial inhibition of hepatic microsomal aminopyrine N-demethylase by caffeine in partially purified cytochrome P450

Cytochrome P-450 substrate interactions were studied with cytochrome P-450 partially purified from livers of untreated, phenobarbital-treated, benzo[a]pyrene-treated and caffeine-treated rats. Partial inhibition of aminopyrine N-demethylase in presence of in vitro caffeine observed with intact microsomes was further investigated in a reconstituted system composed of partially purified cytochrome P-450 and cytochrome c reductase. Caffeine addition (in vitro) to partially purified cytochrome P-450 altered the hexobarbital, aniline and ethylisocyanide induced spectral change, and decreased NADPH oxidation in presence of substrates aminopyrine and acetanilide. NADPH oxidation was found to be increased in presence of aminopyrine and unaltered in presence of acetanilide in reconstituted system having partially purified cytochrome P-450 from caffeine-treated rats. Our studies suggest that caffeine acts as a true modifier of cytochrome P-450 and is possibly responsible for the formation of abortive complexes with aminopyrine.

Modulation of macrophage superoxide release by purine metabolism

Metabolic flux through the purine salvage pathway appears to modulate superoxide secretion by elicited macrophages. Exogenous adenosine, the first substrate of this pathway, stimulates superoxide secretion, and Allopurinol, a specific inhibitor of xanthine oxidase, inhibits superoxide secretion. The effects of these agents are additive since it was possible for each to neutralize the effects of the other when given in combination. In these experiments, the purine salvage pathway was responsible for over ten times the superoxide production attributable to the NADPH oxidase system.

Evidence that NADPH is the actual substrate of the oxidase responsible for the "respiratory burst" of phagocytosing polymorphonuclear leukocytes

The relationship between glucose metabolism and the "respiratory burst" of phagocytosing polymorphonuclear leukocytes (PMN) was studied in a Renex 30-treated cell system of guinea pig PMN by a polarometric technique. Phagocytosing PMN were treated with a detergent (Renex 30) and recovery of respiratory activity was examined by addition of various concentrations of NADP and glucose-6-phosphate (G6P) to determine the availability of endogenously formed NADPH via the hexose monophosphate (HMP) pathway. The oxygen uptake by phagocytosing PMN ceased after the treatment with Renex 30 and was restored by the addition of NADP and G6P. Furthermore, the restoration of oxygen uptake was linearly proportional to the rate of NADPH formation on increase in either NADP or G6P concentration. Resting PMN showed no respiratory activity even in the presence of excess NADP and G6P, in which NADPH was formed at the same rate as in phagocytosing PMN. In a parallel experiment, recovery of respiratory activity was examined in the same system by addition of NAD and glyceraldehyde-3-phosphate (G3P) in that order to clarify whether the respiratory enzyme can utilize NADH formed via the glycolytic pathway. In contrast to the results in the NADPH-forming system, the addition of NAD and G3P induced slight oxygen uptake of Renex 30-treated PMN, but there was no difference in the oxygen uptake between resting and phagocytosis-activated PMN. The results indicated that the primary oxidase responsible for the "respiratory burst" is NADPH oxidase, and that its activity is coupled with glucose oxidation via the HMP pathway without the participation of other metabolic pathways such as glycolysis.

Suicide inactivation of rat liver cytochrome P-450 by chloramphenicol in vivo and in vitro

Intraperitoneal administration of chloramphenicol (100 mg/kg) to phenobarbital-treated rats causes 50% inhibition of liver microsomal 7-ethoxycoumarin and 1,1,2,2 tetrachloroethane metabolism but has no effect on the level of cytochrome P-450 detectable as its carbon monoxide complex or on the NADPH-cytochrome c reductase (EC 1.6.2.4) activity. Both the endogenous NADPH oxidase activity and the enzymatic reduction of cytochrome P-450 are inhibited by chloramphenicol treatment, whereas the Km and Ks for ethoxycoumarin and the cumene hydroperoxide- or iodosobenzene-supported deethylation of ethoxycoumarin are unaffected, suggesting that impaired electron transport to cytochrome P-450 may be the cause of the loss of enzymatic activity. Administration of [14C]chloramphenicol (100 mg/kg) leads to the covalent binding of 0.7 nmole of metabolite(s) per nanomole of the major cytochrome P-450 isozyme. Alkaline hydrolysis of a cytochrome P-450 fraction obtained by chromatography of solubilized 14C-labeled microsomes on octylamino-Sepharose releases oxalic acid and chloramphenicol oxamic acid, whereas enzymatic digestion releases N-epsilon-chloramphenicol oxamyl lysine in addition. These data obtained with radiolabeled chloramphenicol suggest that the same metabolic pathways which lead to the inactivation of cytochrome P-450 in vitro are also operative in vivo.

The O2- generating oxidoreductase of human neutrophils: evidence of an obligatory requirement for calcium and magnesium for expression of catalytic activity

NADPH-dependent O2- generating oxidoreductase activity recovered from cell lysates of phorbol myristate acetate-stimulated human neutrophils exhibits dependence on Ca+2 and Mg+2 for full expression of its catalytic activity. O2- generating activity was completely abolished by exposure of the oxidoreductase to EDTA, then reconstituted by exposure of the enzyme to Ca+2 and Mg+2 in excess of the EDTA concentration used to block catalytic activity. The oxidoreductase responded maximally to either 0.25 mM Ca+2 or 0.80 mM Mg+2. The pH optimum of the oxidoreductase exposed to Ca+2 and Mg+2 is between pH 7.0 and 7.6. The molar ratio of NADPH oxidation to O2- production determined at pH 7.6 in the presence of Ca+2 and Mg+2 is 0.49, indicating 1 mole of NADPH oxidized per 2 moles of O2- formed. Particulate fractions recovered from cell lysates of resting neutrophils exhibited no oxidoreductase activity under the same conditions.

Delineation of the catalytic components of the NADPH-dependent O2- generating oxidoreductase of human neutrophils

Four catalytic components of the NADPH-dependent O2- generating oxidoreductase of human neutrophils have been identified. DCIP reductase, cytochrome c reductase and a chromophore 450-455 reductase are present in phorbol myristate acetate stimulated neutrophils and absent in resting cells and phorbol myristate acetate stimulated chronic granulomatous disease cells. Quinol dehydrogenase activity has also been demonstrated in activated and resting cells. Furthermore, a chromophore absorbing in the reduced state at 450-455 nm participates in superoxide production. This chromophore is reduced by NADPH or duroquinol and is missing in cell lysates derived from a patient with chronic granulomatous disease.

Enhanced superoxide anion release from phagocytes by muramyl dipeptide or lipopolysaccharide

Muramyl dipeptide (MDP) and lipopolysaccharide (LPS) from Escherichia coli were tested for the ability to influence superoxide anion (O2-) release from guinea pig phagocytes. Both MDP and LPS alone did not, by themselves, stimulate O2- release by macrophages and polymorphonuclear leukocytes. However, the preincubation of macrophages with MDP or LPS primed the macrophages to release an enhanced amount of O2- when stimulated by cytochalasin E and wheat germ agglutinin. When polymorphonuclear leukocytes were treated in the same way, only LPS showed an enhancing effect. MDP enhanced NADPH oxidase activity of macrophages, which is probably the reason for enhanced O2- release by MDP.

Subcellular localization and properties of the NAD(P)H oxidase from equine polymorphonuclear leukocytes

The subcellular distribution of the superoxide-forming enzyme in horse polymorphonuclear leukocytes was investigated. After activation of the cells with sodium oleate, a relatively stable and NAD(P)H-dependent oxygen consumption and superoxide production was found in association with the plasma membranes. The pH dependence displayed an optimum near neutrality. The apparent Km values were 38 x 10(-6) mol/l for NADPH and 1,560 x 10(-6) mol/l for NADH, suggesting that NADPH is the physiological donor. The rates of oxygen uptake, O2- production, and NADP consumption were consistent with the stoichiometry: 2 O2 + NADPH leads to 2 O2- + NADP. The failure to demonstrate an increase of NAD(P)H-dependent oxidative activity in the cellular fractions that the investigated NADPH oxidase is identical with the enzyme responsible for the respiratory burst in phagocytizing leukocytes.