DAO
D-amino-acid oxidase (EC 1.4.3.3) (DAAO) (DAMOX) (DAO) [DAMOX]
Publications[править]
D-amino acid oxidase (DAO) is a flavoenzyme, catalysing oxidative deamination of D-amino acids to produce corresponding α-keto acids, ammonia and hydrogen peroxide. In our search for DAO activity among various tissues, we developed a sensitive assay based on hydrogen peroxide production involving enzyme-coupled colorimetric assay with peroxidase. We first optimized buffer components to extract DAO protein from mouse tissues. Here we show that DAO activity was detected in kidney, cerebellum, medulla oblongata, midbrain and spinal cord, but not in liver. In addition, we observed that DAO activity and expression were decreased in thoracic and lumbar regions of spinal cord in aged mice when compared with young mice, indicating that decreased DAO is involved in motoneuron degeneration during senescence. We also found gender difference in DAO activity in the kidney, suggesting that DAO activity is influenced by sexual dimorphism. We newly detected DAO activity in the epididymis, although undetected in testis. Furthermore, DAO activity was significantly higher in the caput region than corpus and cauda regions of epididymis, indicating that D-amino acids present in the testis are eliminated in epididymis. Taken together, age- and gender-dependent DAO activity in each organ may underlie the human pathophysiology regulated by D-amino acid metabolism.
MeSH Terms
- Aging
- Amino Acids
- Animals
- Brain
- D-Amino-Acid Oxidase
- Female
- Kidney
- Male
- Mice
- Mice, Inbred C57BL
- Motor Neurons
- Neurodegenerative Diseases
- Organ Specificity
- Sex Characteristics
- Spinal Cord
- Testis
Keywords
- D-amino acid oxidase
- age- and gender-dependence
- epididymis
- kidney
- spinal cord
Feasible peripheral biomarker for Alzheimer's disease (AD) is lacking. Dysregulation of N-methyl-D-aspartate (NMDA) receptor is implicated in the pathogenesis of AD. D-amino acid oxidase (DAO) and amino acids can regulate the NMDA receptor function. This study aimed to examine whether peripheral DAO and amino acids levels are characteristic of age-related cognitive decline. We enrolled 397 individuals (including amnestic mild cognitive impairment (MCI), mild AD, moderate to severe AD, and healthy elderly). DAO levels in the serum were measured using ELISA. Amino acids levels in serum were measured by high performance liquid chromatography. Severity of the cognitive deficits in subjects was assessed using Clinical Dementia Rating Scale (CDR). The DAO levels increased with the severity of the cognitive deficits. DAO levels were significantly associated with D-glutamate and D-serine levels. The Receiver Operating Characteristics analysis of DAO levels for AD patients vs. healthy controls determined the optimal cutoff value, 30.10, with high sensitivity (0.842) and specificity (0.889) (area under curve = 0.928). This is the first study indicating that the peripheral DAO levels may increase with age-related cognitive decline. The finding supports the hypofunction of NMDA receptor hypothesis in AD. Whether DAO could serve as a potential surrogate biomarker needs further studies.
MeSH Terms
- Aged
- Aged, 80 and over
- Alzheimer Disease
- Amino Acids
- Biomarkers
- Case-Control Studies
- Chromatography, High Pressure Liquid
- Cognitive Aging
- Cognitive Dysfunction
- D-Amino-Acid Oxidase
- Enzyme-Linked Immunosorbent Assay
- Female
- Humans
- Male
- Middle Aged
- Receptors, N-Methyl-D-Aspartate
- Sensitivity and Specificity
- Severity of Illness Index
For elucidation of the regulation mechanisms of intrinsic amounts of D-serine (D-Ser) which modulates the neuro-transmission of N-methyl-D-aspartate receptors in the brain, mutant animals lacking serine racemase (SRR) and D-amino acid oxidase (DAO) were established, and the amounts of D-Ser in the tissues and physiological fluids were determined. D-Ser amounts in the frontal brain areas were drastically decreased followed by reduced SRR activity. On the other hand, a moderate but significant decrease in D-Ser amounts was observed in the cerebellum and spinal cord of SRR knock-out (SRR(-/-)) mice compared with those of control mice, although the amounts of D-Ser in these tissues were low. The amounts of D-Ser in the brain and serum were not altered with aging. To clarify the uptake of exogenous D-Ser into the brain tissues, we have determined the D-Ser of SRR(-/-) mice after oral administration of D-Ser for the first time, and a drastic increase in D-Ser amounts in all the tested tissues was observed. Because both DAO and SRR are present in some brain areas, we have established the double mutant mice lacking SRR and DAO for the first time, and the contribution of both enzymes to the intrinsic D-Ser amounts was investigated. In the frontal brain, most of the intrinsic D-Ser was biosynthesized by SRR. On the other hand, half of the D-Ser present in the hindbrain was derived from the biosynthesis by SRR. These results indicate that the regulation of intrinsic D-Ser amounts is different depending on the tissues and provide useful information for the development of treatments for neuronal diseases.
MeSH Terms
- Aging
- Animals
- Cerebellum
- Chromatography, High Pressure Liquid
- D-Amino-Acid Oxidase
- Mice
- Mice, Knockout
- Neurotransmitter Agents
- Organ Specificity
- Prosencephalon
- Racemases and Epimerases
- Receptors, N-Methyl-D-Aspartate
- Serine
- Spinal Cord
- Stereoisomerism
- Synaptic Transmission
There is little published information on plasma copper and whole blood copper concentrations in cats, and except for extracellular superoxide dismutase (EC SOD), we are unaware of published values for cat cuproenzyme activities. In this study we determined plasma and whole blood copper concentrations, plasma ceruloplasmin (CP), EC SOD and diamine oxidase (DAO) activities, and erythrocyte superoxide dismutase (RBC SOD) activity in a specific pathogen-free colony of cats. Results were evaluated for differences based on age and sex. Blood was obtained from 20 adult cats (10 males, 10 females; >1 year of age) and 20 immature cats (10 males, 10 females; <1 year of age). Copper concentrations were determined using atomic absorption spectrophotometry. EC SOD and RBC SOD activities were determined using the pyrogallol oxidation method, and CP activity was determined by the oxidation of 0 dianisidine dihydrochloride. DAO activity was measured using a colorimetric assay. Differences among groups were analyzed using ANOVA. There were significant differences in mean plasma copper concentration, and CP and DAO activities (P=.001,.0001, and.02, respectively) among the 4 groups of cats. No age differences were identified. Male cats had significantly greater mean ( /- SEM) plasma copper (15.4 /- 0.9 micromol/L versus 11.3 /- 0.6 micromol/L; P =.001) concentrations, and CP (66.8 /- 2.9 U/L versus 39.7 /- 2.1 U/L; P=.0001) and DAO (6.68 /- 0.16 U/L versus 6.15 /- 0.1 U/L; P =.03) activities compared with female cats. Males had significantly greater whole blood copper concentrations (16.16 /- 0.55 micromol/L versus 13.36 /- 0.52 micromol/L; P =.002) than female cats. Differences exist between male and female cats with respect to blood copper concentrations, and CP and DAO activities.
MeSH Terms
- Aging
- Amine Oxidase (Copper-Containing)
- Animals
- Cats
- Ceruloplasmin
- Copper
- Erythrocytes
- Female
- Male
- Sex Factors
- Specific Pathogen-Free Organisms
- Superoxide Dismutase
The daf-2 insulin-like receptor pathway regulates development and life-span in Caenorhabditis elegans. Reduced DAF-2 signaling leads to changes in downstream targets via the daf-16 gene, a fork-head transcription factor which is regulated by DAF-2, and results in extended life-span. Here, we describe the first identification of genes whose expression is controlled by the DAF-2 signaling cascade. dao-1, dao-2, dao-3, dao-4, dao-8 and dao-9 are down-regulated in daf-2 mutant adults compared to wild-type adults, whereas dao-5, dao-6 and dao-7 are up-regulated. The latter genes are negatively regulated by DAF-2 signaling and positively regulated by DAF-16. Positive regulation by DAF-2 on dao-1, dao-4 and dao-8 was mediated by DAF-16, whereas daf-16 mediates only part of DAF-2 signaling for dao-2 and dao-9. Regulation by DAF-2 is most likely DAF-16 independent for dao-3 and hsp-90. RNA levels of dao-5 and dao-6 showed elevated expression in daf-2 adults, as well as being strongly expressed in dauer larvae. In contrast, hsp-90 transcript levels are low in daf-2 mutant adults though they are enriched in dauer larvae, indicating overlapping but not identical mechanisms of efficient life maintenance in stress-resistant dauer larvae and long-lived daf-2 mutant adults. dao-1, dao-8 and dao-9 are homologs of the FK506 binding proteins that interact with the mammalian insulin pathway. dao-3 encodes a putative methylenetetrahydrofolate dehydrogenase. DAO-5 shows 33 % identity with human nucleolar phosphoprotein P130. dao-7 is similar to the mammalian ZFP36 protein. Distinct regulatory patterns of dao genes implicate their diverse positions within the signaling network of DAF-2 pathway, and suggest they have unique contributions to development, metabolism and longevity.
MeSH Terms
- Aging
- Amino Acid Sequence
- Animals
- Base Sequence
- Caenorhabditis elegans
- Caenorhabditis elegans Proteins
- Cloning, Molecular
- Forkhead Transcription Factors
- Gene Expression Profiling
- Gene Expression Regulation
- Genes, Helminth
- Larva
- Molecular Sequence Data
- Multigene Family
- Mutation
- RNA, Double-Stranded
- RNA, Messenger
- Receptor, Insulin
- Reproducibility of Results
- Signal Transduction
- Tacrolimus Binding Proteins
- Transcription Factors
Diamine oxidase (DAO) is an enzyme synthesized primarily in the gastrointestinal mucosal cells. Serum levels of DAO have been used as an indicator of the integrity and/or functional mass of the intestinal mucosa. The enzyme is also produced by the placenta and is elevated in newborn serum. Previous radiometric methods for DAO used tritiated putrescine or cadaverine as substrate. A simple and rapid spectrophotometric procedure for DAO with use of histamine as substrate was developed, and this assay was utilized to evaluate the developmental pattern of activity of DAO in umbilical cord blood of newborn full-term and premature infants, in sequential samples from premature infants, and in samples from infants with necrotizing enterocolitis. The spectrophotometric assay was linear to 200 U per L and was also precise with total imprecision (CV) of 11.9 percent and 3.7 percent at DAO activities of 25.6 U per 1 and 126.1 U per L, respectively. Triglycerides above 275 mg per dL caused a significant reduction in measured activity of DAO; however, this effect could be eliminated by use of ultracentrifugation to remove lipemia. Plasma samples with heparin or ethylenediamine tetraacetic acid (EDTA) as anticoagulant were unsuitable for analysis since DAO activity showed a 24 percent and 32 percent decrease in activity at concentrations of 20 U per mL (heparin) and two mg per mL (EDTA), respectively. Serum samples are the specimen of choice. In infants it was found that the serum activity declined to adult levels by day 12 of life and that this decline is not affected by necrotizing arterocolitis.
MeSH Terms
- Aging
- Amine Oxidase (Copper-Containing)
- Autoanalysis
- Edetic Acid
- Enterocolitis, Pseudomembranous
- Evaluation Studies as Topic
- Female
- Fetal Blood
- Heparin
- Histamine
- Humans
- Infant, Newborn
- Infant, Premature
- Intestinal Mucosa
- Male
- Quality Control
- Reference Values
- Spectrophotometry
- Triglycerides