RESUMO
The present study aimed to develop a reliable pyrosequencing method to detect four single nucleotide polymorphisms (SNPs) of the flavincontaining monooxygenase 3 (FMO3) gene and to compare the ethnic differences in their allelic frequencies. The pyrosequencing method was used to detect four FMO3 SNPs, namely, c.855C>T (N285N, rs909530), c.441C>T (S147S, rs1800822), c.923A>G (E308G, rs2266780) and c.472G>A (E158K, rs2266782). The allelic frequencies of these SNPs in 122 unrelated Korean subjects were as follows: i) 44.7% for c.855C>T; ii) 23.4% for c.441C>T; iii) 23.0% for c.923A>G; and iv) 27.1% for c.472G>A. Linkage disequilibrium (LD) analysis revealed that the SNPs c.923A>G and c.472G>A exhibited a strong LD (D'=0.8289, r2=0.5332). In conclusion, the pyrosequencing method developed in this study was successfully applied to detect the c.855C>T, c.441C>T, c.923A>G and c.472G>A SNPs of FMO3.
Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Oxigenases/genética , Adulto , Povo Asiático/genética , Frequência do Gene , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Oxigenases/sangue , Polimorfismo de Nucleotídeo Único , Reprodutibilidade dos Testes , República da Coreia , Adulto JovemRESUMO
Our recent paper demonstrated the ability to predict in vivo clearance of flavin-containing monooxygenase (FMO) drug substrates using in vitro human hepatocyte and human liver microsomal intrinsic clearance with standard scaling approaches. In this paper, we apply a physiologically based pharmacokinetic (PBPK) modeling and simulation approach (M&S) to predict the clearance, area under the curve (AUC), and Cmax values together with the plasma profile of a range of drugs from the original study. The human physiologic parameters for FMO, such as enzyme abundance in liver, kidney, and gut, were derived from in vitro data and clinical pharmacogenetics studies. The drugs investigated include itopride, benzydamine, tozasertib, tamoxifen, moclobemide, imipramine, clozapine, ranitidine, and olanzapine. The fraction metabolized by FMO for these drugs ranged from 21% to 96%. The developed PBPK models were verified with data from multiple clinical studies. An attempt was made to estimate the scaling factor for recombinant FMO (rFMO) using a parameter estimation approach and automated sensitivity analysis within the PBPK platform. Simulated oral clearance using in vitro hepatocyte data and associated extrahepatic FMO data predicts the observed in vivo plasma concentration profile reasonably well and predicts the AUC for all of the FMO substrates within 2-fold of the observed clinical data; seven of the nine compounds fell within 2-fold when human liver microsomal data were used. rFMO overpredicted the AUC by approximately 2.5-fold for three of the nine compounds. Applying a calculated intersystem extrapolation scalar or tissue-specific scalar for the rFMO data resulted in better prediction of clinical data. The PBPK M&S results from this study demonstrate that human hepatocytes and human liver microsomes can be used along with our standard scaling approaches to predict human in vivo pharmacokinetic parameters for FMO substrates.
Assuntos
Hepatócitos/metabolismo , Taxa de Depuração Metabólica/fisiologia , Modelos Biológicos , Oxigenases/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Previsões , Hepatócitos/efeitos dos fármacos , Humanos , Masculino , Taxa de Depuração Metabólica/efeitos dos fármacos , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismo , Pessoa de Meia-Idade , Oxigenases/farmacocinética , Especificidade por Substrato/efeitos dos fármacos , Especificidade por Substrato/fisiologia , Fatores de Tempo , Adulto JovemRESUMO
The serum proteomic profiles of mice exposed to terrified-sound-induced stress and after stress release were investigated. Serum samples from 32 mice were divided into four groups (n = 8 each) and analyzed using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry techniques (MALDI-TOF MS) combined with magnetic bead-based weak cation-exchange chromatography. ClinProTools software identified several distinct markers that differed between the stressed and control groups and between the stress released and stressed released controls. Of 33 m/z peaks that differed among the four groups, 17 were significantly different (P < 0.05). Five peaks (m/z: 2793.37, 2924.86, 1979.90, 3492.49, 3880.24) showed significant differences in expression after exposure to terrified-sound stress and returned to control levels after stress release. These were sequence identified as peptide regions of dimethylaniline monooxygenase, myosin-9, uncharacterized protein in Rattus norvegicus, apolipoprotein C-I, and plasma serine protease inhibitor (Serpina 5). Our study provides the first evidence of significant changes in serum proteomic profiles in mice exposed to terrified-sound stress, which suggests that protein expression profiles are affected by the stress. Normal expression levels were restored after stress release, suggesting the activation of self-adjustment mechanisms for the recovery of protein expression levels altered by this stress.
Assuntos
Medo , Proteoma/metabolismo , Som/efeitos adversos , Estresse Psicológico/sangue , Animais , Apolipoproteína C-I/sangue , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Miosinas/sangue , Oxigenases/sangue , Inibidor da Proteína C/sangue , Proteoma/genética , Estresse Psicológico/etiologiaAssuntos
Injúria Renal Aguda/sangue , Imunoensaio/métodos , Oxigenases/sangue , Animais , Feminino , Humanos , Inositol Oxigenase , MasculinoRESUMO
BACKGROUND: Acute kidney injury (AKI) affects 45% of critically ill patients, resulting in increased morbidity and mortality. The diagnostic standard, plasma creatinine, is nonspecific and may not increase until days after injury. There is significant need for a renal-specific AKI biomarker detectable early enough that there would be a potential window for therapeutic intervention. In this study, we sought to identify a renal-specific biomarker of AKI. METHODS: We analyzed gene expression data from normal mouse tissues to identify kidney-specific genes, one of which was Miox. We generated monoclonal antibodies to recombinant myo-inositol oxygenase (MIOX) and developed an immunoassay to quantify MIOX in plasma. The immunoassay was tested in animals and retrospectively in patients with and without AKI. RESULTS: Kidney tissue specificity of MIOX was supported by Western blot. Immunohistochemistry localized MIOX to the proximal renal tubule. Serum MIOX, undetectable at baseline, increased 24 h following AKI in mice. Plasma MIOX was increased in critically ill patients with AKI [mean (SD) 12.4 (4.3) ng/mL, n = 42] compared with patients without AKI [0.5 (0.3) ng/mL, n = 17] and was highest in patients with oliguric AKI [20.2 (7.5) ng/mL, n = 23]. Plasma MIOX increased 54.3 (3.8) h before the increase in creatinine. CONCLUSIONS: MIOX is a renal-specific, proximal tubule protein that is increased in serum of animals and plasma of critically ill patients with AKI. MIOX preceded the increases in creatinine concentration by approximately 2 days in human patients. Large-scale studies are warranted to further investigate MIOX as an AKI biomarker.
Assuntos
Injúria Renal Aguda/sangue , Imunoensaio/métodos , Oxigenases/sangue , Injúria Renal Aguda/enzimologia , Animais , Anticorpos Monoclonais/imunologia , Biomarcadores/sangue , Western Blotting , Estado Terminal , Feminino , Humanos , Imuno-Histoquímica , Inositol Oxigenase , Masculino , Camundongos , Oxigenases/genética , Oxigenases/imunologia , RNA Mensageiro/genéticaRESUMO
The pharmacokinetics of the atypical antipsychotic, olanzapine, display large interindividual variation leading to multiple-fold differences in drug exposure between patients at a given dose. This variation in turn gives rise to the need for individualized dosing in order to avoid concentration-dependent adverse effects or therapeutic failure. Genetically determined differences in olanzapine metabolism represent a less studied source of variability in comparison to environmental and physiological factors. In this review, we summarize available in vitro and in vivo data addressing the influence of polymorphisms in drug-metabolizing enzymes on olanzapine serum exposure. The polymorphic CYP2D6 enzyme appears to have no significant influence on olanzapine steady-state serum concentrations. The formation of the various olanzapine metabolites is influenced by polymorphisms in the genes coding for CYP1A2, CYP1A expression regulator AHR, UGT1A4 and UGT2B10, as well as FMO3. An impact on steady-state olanzapine serum concentrations has been suggested for variants of CYP1A2 and UGT1A4, with somewhat conflicting findings. The potential involvement of FMO1 and CYP3A43 in olanzapine disposition has also been suggested but needs future validation.
Assuntos
Benzodiazepinas/metabolismo , Inativação Metabólica/genética , Farmacogenética , Citocromo P-450 CYP1A1/sangue , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1A1/farmacocinética , Citocromo P-450 CYP1A2/sangue , Citocromo P-450 CYP1A2/genética , Citocromo P-450 CYP1A2/farmacocinética , Citocromo P-450 CYP2D6/sangue , Citocromo P-450 CYP2D6/genética , Citocromo P-450 CYP2D6/farmacocinética , Feminino , Glucuronosiltransferase/sangue , Glucuronosiltransferase/genética , Glucuronosiltransferase/farmacocinética , Humanos , Olanzapina , Oxigenases/sangue , Oxigenases/genética , Oxigenases/farmacocinéticaRESUMO
We postulated that a deficiency of flavin monooxygenase (FMO)-a ferrireductase component of cells-could produce sideroblastic anemia. FMO is an intracellular ferrireductase which may be responsible for the obligatory reduction of ferric to ferrous iron so that reduced iron can be incorporated into heme by ferrochelatase. Abnormalities of this mechanism could result in accumulation of excess ferric iron in mitochondria of erythroid cells to produce ringed sideroblasts and impair hemoglobin synthesis. To investigate this hypothesis we obtained blood from patients with sideroblastic anemia and normal subjects. Extracts of peripheral blood lymphocytes were used to measure ferrireduction by utilization of NADPH. Lymphoid precursors are reported to accumulate iron in mitochondria similarly to erythroid precursors. Utilization of lymphoid precursors avoided the need for bone marrow aspirations. We studied three patients with sideroblastic anemia. One patient and his asymptomatic daughter had a significant decrease in ferrireductase activity. They also had markedly diminished concentrations of FMO in lymphocyte protein extracts on Western blots. This was accompanied by increased concentration of mobilferrin in the extracts. These results suggest that abnormalities of FMO and mobilferrin may cause sideroblastic anemia and erythropoietic hemochromatosis in some patients.
Assuntos
Anemia Sideroblástica/etiologia , Proteínas de Ligação ao Ferro , Oxigenases/deficiência , Idoso , Idoso de 80 Anos ou mais , Anemia Sideroblástica/sangue , Anemia Sideroblástica/enzimologia , Western Blotting , Proteínas de Transporte/sangue , Proteínas de Transporte/imunologia , Saúde da Família , Feminino , Ligação Genética , Humanos , Ferro/sangue , Ferro/imunologia , Linfócitos/metabolismo , Masculino , NADH NADPH Oxirredutases/sangue , NADH NADPH Oxirredutases/deficiência , Oxigenases/sangue , Cromossomo XRESUMO
A non-invasive urine analysis method to determine the in-vivo flavin-containing mono-oxygenase (FMO) activity catalysing N-oxidation of ranitidine (RA) was developed and used to phenotype a Korean population. FMO activity was assessed by the molar concentration ratio of RA and RANO in the bulked 8 h urine. This method was used to determine the FMO phenotypes of 210 Korean volunteers (173 men and 37 women, 110 nonsmokers and 100 smokers). Urinary RA/RANO ratio, representing the metabolic ratio and the reciprocal index of FMO activity, ranged from 5.67-27.20 (4.8-fold difference) and was not different between men and women (P = 0.76) or between smokers and nonsmokers (P = 0.50). The frequencies of RA/RANO ratios were distributed in a trimodal fashion. Among the 210 Korean subjects, 93 (44.3%) were fast metabolizers, 104 (49.5%) were intermediate metabolizers and 13 (6.2%) were slow metabolizers. Subsequently, the relationship between the ranitidine N-oxidation phenotypes and FMO3 genotypes, determined by the presence of two previously identified mutant alleles (Glu158Lys: FMO3/Lys158 and Glu308Gly: FMO3/Gly308 alleles) commonly found in our Korean population was examined. The results showed that subjects who were homozygous and heterozygous for either one or both of the FMO3/Lys158 and FMO3/Gly308 mutant alleles had significantly lower in-vivo FMO activities than those with homozygous wild-type alleles (FMO3/Glu158 and FMO3/Glu308) (P < 0.001, Mann-Whitney U-test). Furthermore, the FMO activities of subjects with either FMO3/Lys158 or FMO3/Gly308 mutant alleles were almost identical to those having both FMO3 mutant alleles (FMO3/Lys158 and FMO3/Gly308). These two mutant alleles located, respectively, at exons 4 and 7 in the FMO3 gene appeared to be strongly linked by cis-configuration in Koreans. Therefore, we concluded that presence of FMO3/Lys158 and FMO3/Gly308 mutant alleles in FMO3 gene is responsible for the low ranitidine N-oxidation (FMO3 activity) in our Korean population.
Assuntos
Oxigenases/genética , Oxigenases/urina , Ranitidina/urina , Adulto , Alelos , Substituição de Aminoácidos , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta a Droga , Feminino , Frequência do Gene , Ligação Genética , Genótipo , Humanos , Coreia (Geográfico) , Masculino , Mutação/genética , Oxirredução , Oxigenases/sangue , Fenótipo , Ranitidina/análogos & derivados , Valores de Referência , Fatores Sexuais , Fumar/genética , Fumar/metabolismoRESUMO
The authors present data on disorders of energy metabolism in erythrocytes, of microsomal monooxygenases and of free-radical oxidation in blood and urine of workers engaged into oil-processing industry. Studies revealed considerable changes in RBC adenyl system parameters, in chemiluminescence of blood and urine, in monooxygenase system. Nonspecific therapy in sanatorium appears to better these aspects.
Assuntos
Indústria Química , Sistema Enzimático do Citocromo P-450/metabolismo , Metabolismo Energético/fisiologia , Radicais Livres/metabolismo , Doenças Profissionais/diagnóstico , Oxigenases/metabolismo , Petróleo , Sistema Enzimático do Citocromo P-450/sangue , Sistema Enzimático do Citocromo P-450/urina , Família 2 do Citocromo P450 , Radicais Livres/sangue , Radicais Livres/urina , Humanos , Doenças Profissionais/epidemiologia , Doenças Profissionais/terapia , Oxigenases/sangue , Oxigenases/urina , Resultado do TratamentoRESUMO
The nitric oxide (N0-releasing agents sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) inhibit dioxygenase activity of lipoxygenase in human platelets and human CHP100 neuroblastoma cells, leading the latter to necrosis. The effect of both NO-donors on the dioxygenase reaction was investigated by using soybean lipoxygenase type II (LOX-2) as a model for the mammalian enzyme. SNP and SNAP were competitive inhibitors of LOX-2, with inhibition constants of 525 microM and 710 microM, respectively. Both compounds inactivated LOX-2 by reducing the catalytic iron to the inactive Fe(II) form and counteracted the H2O2-mediated activation of the LOX-2 catalyzed dioxygenase reaction. Similarly, the co-oxidative and per-oxidative activities of LOX-2 were also inhibited by the NO-releasing agents. These findings suggest that the biological role played by NO can be mediated, at least in part, by the inactivation of lipoxygenase, a key-enzyme for the arachidonic acid metabolism in human cells.
Assuntos
Plaquetas/enzimologia , Inibidores de Lipoxigenase/farmacologia , Lipoxigenase/metabolismo , Óxido Nítrico/farmacologia , Nitroprussiato/farmacologia , Oxigenases/antagonistas & inibidores , Penicilamina/análogos & derivados , Morte Celular/efeitos dos fármacos , Linhagem Celular , Humanos , Cinética , Lipoxigenase/sangue , Necrose , Neuroblastoma , Oxigenases/sangue , Penicilamina/farmacologia , S-Nitroso-N-Acetilpenicilamina , Células Tumorais CultivadasRESUMO
The hepatic blood flow and monooxygenase system activity were studied in 68 ischemic [correction of coronary] heart disease patients aged 37-68 [correction of 40-80] years who had functional class III-IV effort angina and 12 healthy volunteers matched by age. An analysis of the finding indicated that in patients with angina pectoris, the hepatic blood flow index decreased, the pharmacokinetic parameters of antipyrin impaired, the degree of these impairments depended on the severity of the clinical course of angina pectoris.
Assuntos
Circulação Hepática , Fígado/enzimologia , Isquemia Miocárdica/fisiopatologia , Oxigenases/sangue , Adulto , Idoso , Angina Pectoris/enzimologia , Angina Pectoris/fisiopatologia , Antipirina/sangue , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/enzimologia , Esforço FísicoRESUMO
S-carboxy-L-methylcysteine was used to assess the activity of the S-oxidation pathway of sulphur metabolism in 35 patients with systemic lupus erythematosus (SLE); 25 (71%) showed impaired sulphoxidation and 21 (60%) produced virtually no sulphoxides, compared with 17 (36%) and 2 (4%), respectively, of 47 healthy controls. The substrate/product ratio of cysteine oxygenase (plasma cysteine/sulphate) was significantly higher in SLE patients than in controls (median [interquartile range] 362 [224-588] vs 65 [44-111]; p less than 0.00001). The alternative pathway of sulphur metabolism, S-methylation, catalysed by thiolmethyltransferase, was not impaired in the SLE patients. There is a biochemical difference in sulphur metabolism between SLE and rheumatoid arthritis, since both pathways are impaired in the latter disorder.
Assuntos
Carbocisteína/metabolismo , Dioxigenases , Lúpus Eritematoso Sistêmico/metabolismo , Metiltransferases/metabolismo , Enxofre/metabolismo , Adulto , Idoso , Cisteína Dioxigenase , Humanos , Lúpus Eritematoso Sistêmico/enzimologia , Pessoa de Meia-Idade , Oxirredução , Oxigenases/sangue , Sulfatos/sangueAssuntos
Amianto/efeitos adversos , Poeira/efeitos adversos , Peroxidação de Lipídeos/efeitos dos fármacos , Exposição Ocupacional/efeitos adversos , Oxigenases/efeitos dos fármacos , Adulto , Antioxidantes , Asbestose/sangue , Bronquite/sangue , Doença Crônica , Sistema Enzimático do Citocromo P-450/sangue , Sistema Enzimático do Citocromo P-450/efeitos dos fármacos , Humanos , Pessoa de Meia-Idade , Doenças Profissionais/sangue , Oxigenases/sangueRESUMO
Metabolism of arachidonic acid in neutrophils was studied in vitro in blood samples obtained from 36 patients with Hodgkin's disease of various stage and histology and 32 healthy donors. The basic metabolites were: leucotriene B4, such products of its omega-oxidation as 20-hydroxy-leucotriene B4 (20-OH-LTB4) and 20-carboxy-leucotriene B4 (20-COOH-LTB4), and 5-hydroxyeicosatetraenic acid. Their profile proved identical in patients with Hodgkin's disease and healthy donors. Most patients with Hodgkin's disease showed a decrease in leucotriene B4 and 5-hydroxyeicosatetraenic acid and an increase in the level of omega oxidation of leucotriene B4 as assessed by omega catabolite/leucotriene B4 ratio. The levels of 5-hydroxyeicosatetraenic acid and leucotriene B4 omega-oxidation were found to depend upon histology and stage of Hodgkin's disease. They were nearly normal in patients with stage III, mixed cellular disease, B-symptoms and signs of biologic activity of tumor. A direct correlation was established between the level of leucotriene B4 omega oxidation in neutrophils and that of ceruloplasmin in blood serum of patients with various stages of Hodgkin's disease.
Assuntos
Ácidos Araquidônicos/sangue , Doença de Hodgkin/sangue , Neutrófilos/enzimologia , Adolescente , Adulto , Ácido Araquidônico , Ceruloplasmina/metabolismo , Sistema Enzimático do Citocromo P-450/sangue , Feminino , Humanos , Ácidos Hidroxieicosatetraenoicos/sangue , Leucotrieno B4/sangue , Masculino , Pessoa de Meia-Idade , Oxirredução , Oxigenases/sangueRESUMO
Correlations between the clinical course of true eczema and liver monooxigenase system, assessed by antipyrine test, were investigated in patients suffering from the condition. The findings evidence that antipyrine half-life period is prolonged in the patients vs. the reference subjects. Clinical status parameters were more marked and disease duration longer in the patients with a longer antipyrine half-life (over 12 hrs). A correlation between antipyrine half-life period and the disease standing was revealed.
Assuntos
Eczema/enzimologia , Fígado/enzimologia , Oxigenases/sangue , Adolescente , Adulto , Antipirina/sangue , Doença Crônica , Dermatite Esfoliativa/enzimologia , Feminino , Meia-Vida , Humanos , Masculino , Pessoa de Meia-IdadeAssuntos
Antipirina , Fígado/enzimologia , Oxigenases/sangue , Antipirina/sangue , Erros de Diagnóstico , Feminino , Humanos , Masculino , Matemática , Fatores de TempoRESUMO
Indoleamine 2,3-dioxygenase (IDO) is an interferon (IFN)-induced protein that initiates the metabolism of tryptophan along the kynurenine pathway. Although IDO can be induced by IFN-gamma in many cell types, only mononuclear phagocytes have been shown to be induced to decyclize tryptophan by all three IFN classes. Since tryptophan is an essential amino acid necessary for a variety of metabolic processes, depletion of available tryptophan may be an important mechanism for control of rapidly-dividing microbial pathogens and tumors. The purpose of this review is to present evidence that documents the effects of IFN-induced IDO on prokaryotic and eukaryotic pathogens, as well as on a variety of tumor cell lines.
Assuntos
Interferons/fisiologia , Oxigenases/fisiologia , Animais , Atividade Bactericida do Sangue , Ciclo Celular , Humanos , Técnicas In Vitro , Indolamina-Pirrol 2,3,-Dioxigenase , Interferons/sangue , Leucócitos Mononucleares/fisiologia , Neoplasias Experimentais/patologia , Oxigenases/sangue , Toxoplasma/imunologia , Triptofano/metabolismo , Triptofano OxigenaseRESUMO
Liver monoxygenase system function has been examined in psoriasis patients and possible modifications of current methods of therapy analyzed with due consideration for the detected disorders. A total of 139 patients with various clinical forms of psoriasis have been examined. The function of the liver monoxygenase system has been examined with the use of antipyrine test. The studies have revealed that this system's disorders are most marked in the patients with psoriatic eruptions involving a significant area, in whom the disease runs a protracted severe course. Twenty patients with normal and impaired functions of the monoxygenase system have been administered combined treatment including zixorin (600 mg orally once a week). The results evidence that zixorin improves the therapy efficacy, particularly in the patients with depressed activity of the liver microsomal enzymes. PUVA therapy has been administered to some patients. Zixorin has alleviated the side effects of phototherapy.
Assuntos
Fígado/enzimologia , Oxigenases/sangue , Psoríase/enzimologia , Adolescente , Adulto , Antipirina , Compostos Benzidrílicos/uso terapêutico , Doença Crônica , Quimioterapia Combinada , Indução Enzimática/efeitos dos fármacos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oxigenases/biossíntese , Terapia PUVA , Psoríase/complicações , Psoríase/tratamento farmacológicoRESUMO
Arachidonate 5-lipoxygenase purified from porcine leukocytes was incubated with (5S)-hydroperoxy-6,8,11,14-eicosatetraenoic acid. In addition to degradation products of leukotriene A4 (6-trans-leukotriene B4 and its 12-epimer and others), (5S,6R)-dihydroperoxy-7,9,11,14-eicosatetraenoic acid was produced as a major product especially when the incubation was performed on ice rather than at room temperature. The amount of the (5S,6R)-dihydroperoxy acid was close to the total amount of leukotriene A4 degradation products. Under the anaerobic condition, production of the (5S,6R)-dihydroperoxy acid was markedly reduced. 5-Hydroxy-6,8,11,14-eicosatetraenoic acid could be a substrate of the enzyme and was transformed predominantly to a compound identified as (5S)-hydroxy-(6R)-hydroperoxy-7,9-trans-11,14-cis-eicosatetraenoic acid at about 1-2% rate of arachidonate 5-oxygenation. These findings indicated that the purified 5-lipoxygenase exhibited a 6R-oxygenase activity with (5S)-hydroxy and (5S)-hydroperoxy acids as substrates. The 6R-oxygenase activity, like the leukotriene A synthase activity, was presumed to be an integral part of 5-lipoxygenase because it required calcium and ATP and was affected by selective 5-lipoxygenase inhibitors.