Metabolism Of Pipecolic Acid Research Articles

Пероксисомні біогенні порушення в спектрі синдрому Цельвегера: діагностика, моніторинг і лікування відповідно до рекомендацій глобальної фундації пероксисомних захворювань

Стаття присвячена сучасним принципам діагностики та лікування пероксисомних біогенних порушень у спектрі синдрому Цельвегера відповідно до рекомендацій глобальної фундації пероксисомних захворювань 2016 р. Автори представили клінічні особливості захворювань даного спектра. Ураження нервової, кісткової, сечовидільної, ендокринної, сенсорної систем і зубної емалі є характерною ознакою захворювання. Окремо виділено власне клінічне спостереження, пов’язане з порушенням окислення жирних кислот із дуже довгими ланцюгами в дитини раннього віку. Розділ діагностики захворювань спектра синдрому Цельвегера заснований на світових стандартах і включає маркери β-окислення дуже довголанцюжкових жирних кислот, а також α-окислення пристанової і фітанової кислот, метаболізму піпеколінової кислоти й інших пероксисомних дисфункцій. Остаточний діагноз пероксисомних біогенних порушень у спектрі синдрому Цельвегера на сучасному етапі встановлюється методом генетичного тестування, за допомогою методів секвенування нового покоління для генів PEX. Тяжкість неврологічних розладів і прогредієнтний перебіг захворювання, а також можливість лікування Х-зчепленої адренолейкодистрофії відкрили перспективи скринінгу для Х-зчепленої адренолейкодистрофії (X-ALD), заснованого на комбінації рідинної хроматографії і тандемної мас-спектрометрії (LC-MS/MS), для виявлення підвищених рівнів VLCFA у новонароджених у плямах крові. Клінічний моніторинг із моменту встановлення діагнозу включає корекцію стартових порушень і виявлення симптомів захворювання, що з’являються пізніше.

Clinical and genetic characteristics and detection of urinary pipecolic acid in pyridoxine dependent epilepsy

To analyze the clinical and genetic characteristics of patients with pyridoxine dependent epilepsy (PDE), and build a method to detect and analyze the concentration of urinary pipecolic acid in PDE patients receiving pyridoxine treatment. Twelve patients (8 were male, 4 were female) were diagnosed as PDE in Peking University First Hospital between April 2012 and September 2015. The clinical manifestations, diagnosis and treatment process, video-electroencephalogram, magnetic resonance imaging were retrospectively analyzed. ALDH7A1 gene was detected using Sanger sequencing or targeted next-generation sequencing. The concentration of urinary pipecolic acid in PDE patients was detected with gas chromatography-mass spectrometry (GC-MS), as well as in some non-PDE children served as normal control. All controls, 58 cases totally, were neonates born in our hospital or children came to our hospital for reasons such as syncope (without disturbing pipecolic acid metabolism) from November 2015 to January 2016. Of them, 25 were ≤6 months old(14 were male, 11 were female), 33 were >6 months old(14 were male, 19 were female). The Student's t-test or Mann-Whitney U test was used for comparing the pipecolic acid between the two groups. Correlation analysis was conducted using Pearson or Spearman test. Of the 12 patients, seven of them were abnormal at birth. The age of epilepsy onset was from 5 h to 5 months, within 10 d in 8 patients. After a diagnostic delay time of 15 d to 20 months, seizures in all patients were controlled by pyridoxine monotherapy, at a dose of higher than 10.0 mg/(kg·d) in 10 patients, and 8.5 and 2.5 mg/(kg·d) in the other 2 patients respectively. The range of maintenance dose was 2.5-20.0 mg/(kg·d) during the follow up. Interictal electroencephalogram showed nonspecific abnormality in 10, normal in 2. Brain magnetic resonance imaging showed nonspecific abnormality in 7, normal in 5. ALDH7A1 mutations were found in all patients, including 15 different mutation sites, four of which were never reported before. Splicing mutation IVS11+ 1G>A was carried in 6 patients, with a frequency of 25% (6/24). At the last follow-up, eleven patients were in various degree of psychomotor development delay, including the 4 patients with severe delay in whom birth abnormalities presented, and no significant delay was found in one patient. The concentration of urinary pipecolic acid in control: age ≤6 months, median 8.47 (0.46-35.33) mmol/mol creatinine; age >6 months, median 0.66 (0.12-3.52) mmol/mol creatinine. The concentration of urinary pipecolic acid was different between two groups of control (Z=-5.464, P<0.01). Twelve patients were all older than 6 months when they were tested, and the concentration was only mildly elevated in one patient, the range of 12 patients was 0.14-4.08 mmol/mol creatinine. The concentration was not significantly different between the control with age >6 months and our PDE patients (Z=-0.655, P>0.05). There were no significant correlations between the concentration of urinary pipecolic acid and the initial dose or maintenance dose at last follow-up of pyridoxine (r=0.418 and 0.166, P=0.176 and 0.607). Seizures start in early infancy in most PDE patients. The splicing mutation IVS11+ 1G>A is supposed to be a probable"hotspot"mutation with a high frequency in Chinese PDE patients. Most patients have different levels of psychomotor development delay after seizures are controlled, and the patients with birth abnormalities may have worse outcomes. No relationships between the diagnostic delay time and the development outcome are found. The concentration of urinary pipecolic acid can return to normal during treatment with pyridoxine.

Pipecolic acid concentrations in brain tissue of nutritionally pyridoxine‐deficient rats

Elevated concentrations of pipecolic acid have been reported in plasma and CSF of patients with pyridoxine-dependent epilepsy, but its molecular background is unclear. To investigate any further association of pyridoxine and pipecolic acid metabolism, we have performed an animal trial and have measured the concentration of pipecolic acid in brain tissue of rats with nutritional pyridoxine deficiency and in control littermates. Concentrations of pyridoxal phosphate were significantly reduced in brain tissue of pyridoxine-deficient rats (p < 0.001), while concentrations of pipecolic acid were not significantly different from the normally nourished control group (p = 0.3). These data indicate that a direct association of pyridoxine and pipecolic acid metabolism is unlikely. We therefore assume that the characteristic elevation of pipecolic acid in pyridoxine-dependent epilepsy could rather be a secondary phenomenon with the primary defect of pyridoxine-dependent epilepsy being located outside the pipecolic acid pathway.

Quantitative studies of the in vitro production of pipecolic acid by rumen protozoa and its degradation by rumen bacteria

An in vitro study was conducted to quantitatively investigate the metabolism of pipecolic acid (Pip), a neuromodulator, by mixed rumen bacteria (B), mixed rumen protozoa (P), a combination of B and P (BP), species-enriched rumen protozoal suspension (Polyplastron sp., Diploplastron sp., entodinia and Entodinium caudatum) and pure cultures of several isolates of rumen bacteria (Prevetolla bryantii, Prevetolla albensis, Streptococcus bovis, Veillonella parvula, Megasphaera elsdenii and Ruminococcus albus). Only P produced Pip from L-lysine (1.0 mmol/L L-Lys) at a rate of 83.5 ± 1.6 µmol/L/h and even in BP, Pip was produced from L-Lys by P and increased at a rate of 31.2 ± 3.8 µmol/L/h. Pip production by P was highest when the substrate (L-Lys) concentration was 6 mmol/L and then the rate was 580 ± 36 µmol/L/h. Pipecolic acid production by P suspension enriched with different species of protozoa showed that Polyplastron sp. had the highest Pip production rate of 0.907 ± 0.092 µmol/L/mg protozoal protein per h, and Diploplastron sp. had the lowest rate of 0.55 ± 0.13 µmol/L/mg protozoal protein per h. The addition of D-Lys (1.0 mmol/L) as a substrate to the P suspension revealed that P were also able to produce Pip from D-Lys, though at a lower rate (1/3) compared with L-Lys (1.0 mmol/L), suggesting the presence of epimerases in P. It was confirmed that B were unable to produce Pip from L- or D-Lys. Only B degraded Pip (1.0 mmol/L) after a lag phase at a rate of 56.0 ± 1.5 µmol/L/h. The B suspension was able to degrade D-Lys, though the products were not identified. Pip degradation by pure culture of some species of rumen bacteria showed that P. bryantii and R. albus had the highest rate followed by P. albensis, S. bovis and M. elsdenii with a low rate of Pip degradation. Veillonella parvula showed no ability to degrade Pip. The results suggest that a fairly large proportion of rumen-produced Pip is likely to be absorbed by the host animal before degradation by rumen bacteria.

Hepatic peroxisomes in isolated hyperpipecolic acidaemia: evidence supporting its classification as a single peroxisomal enzyme deficiency.

Hyperpipecolic acidaemia is still regarded as a peroxisomal assembly deficiency. The enzyme responsible for the accumulation of pipecolic acid is located in the peroxisomes in man. We studied the appearance and alterations of peroxisomes in liver biopsy material from three unrelated children suffering from isolated hyperpipecolic acidaemia, in which only the metabolism of pipecolic acid is disturbed, using light and electron microscopy after cytochemical staining for visualisation of peroxisomes. Morphometric results showed the presence of normal-sized to small peroxisomes, an increase in number and abnormally shaped organelles, suggesting enhancement of metabolic efficiency. In one case enlarged organelles were observed. Skin fibroblasts were studied in all patients: their peroxisomes appeared to be normal. The obvious presence of peroxisomes in isolated HPA indicates that this disorder should be classified as a single peroxisomal enzyme deficiency.

Effects of starvation and immobilization on imino acids in mouse brain and peripheral tissues

Effects of starvation and immobilization on the concentration of pipecolic acid and proline in mouse brain regions, liver, heart, kidney and blood plasma were analyzed. Pipecolic acid concentration in mouse brain and liver was increased after 24 or 48 h starvation, while proline concentration was not affected. Significant increases in levels of pipecolic acid were also observed in the rhombencephalon, liver and heart after 3 h immobilization. Proline in the blood plasma and kidney was decreased, while that in liver was increased, by the immobilization. Thus, the effect of such stress on concentration of pipecolic acid differed from that seen with proline. The possible involvement of pipecolic acid in synaptic mechanisms in the central nervous system and/or in pathogenesis of the diseases related to abnormal pipecolic acid metabolism should be given attention.

Localization of pipecolic acid metabolism in rat liver peroxisomes: probable explanation for hyperpipecolataemia in Zellweger syndrome.

The metabolism of [14C]pipecolic acid was studied in peroxisomal fractions of rat liver obtained by density gradient centrifugation in Percoll. The production rate of [14CO2] was used to measure the metabolic activity of the fractions towards [14C]carboxypipecolic acid as a substrate. It was shown that this activity was located in the peroxisomal fractions by comparison with the peroxisomal marker enzyme urate oxidase (EC 1.7.3.3). The process was markedly elevated by the addition of FAD. The apparent Km for DL-pipecolic acid was found to be 1.2 mmol L-1. Addition of ATP (1 mmol L-1) did not influence the decarboxylation rate of pipecolic acid. These results might explain the defective metabolism of pipecolic acid in patients with Zellweger syndrome who are lacking peroxisomes.

Accumulation, elimination, release and metabolism of pipecolic acid in the mouse brain following intraventricular injection.

Following i.c.v. (intracerebral ventricular) injections of D,L-[3H]pipecolic acid (PA), it is reabsorbed from the ventricles and redistributed to various brain regions. The highest accumulation is found in three brain regions ipsilateral to the injection site, hippocampus, neocortex, striatum, and in the diencephalon. Following preloading in vivo, the radioactivity is released from hippocampus slices in the perfusion medium after depolarization induced by high K+. During perfusion with a Ca++ free medium containing EGTA, a significant reduction of release is observed. The radioactivity of D,L-[3H]PA in the brain shows a more rapid phase of decrease from 0 to 2 hours and a slower phase from 2 to 5 hours. At 5 hours, only 28% radioactivity, represented mainly by PA, is left in the brain. Kidney secretion represents the major route of elimination of the injected PA. The presence of alpha-aminoadipic acid both in brain and urine was observed. Probenecid (200 mg/kg) significantly increases the accumulation of i.c.v. injected D,L-[3H]PA in brain and kidney. The presence of a regional accumulation of PA in certain brain regions, its metabolism in brain, its enhanced retention following probenecid administration and its Ca++ dependent release following high K+ stimulation, all constitute indirect evidence for a neuronal localization of this brain endogenous aminoacid.

O-9 - Accumulation, elimination and metabolism of pipecolic acid in mouse brain

O-9 - Accumulation, elimination and metabolism of pipecolic acid in mouse brain

Comparative rates of metabolism of pipecolic acid in several animal species

1. 1. The rate of metabolism of pipecolic acid, measured in liver and kidney, varied 1000 fold among 10 animal species. Degradation of l-pipecolic acid by kidney in rat and mouse was 0.11 and 0.31 pmoles/min/mg protein, respectively; in monkey and human, 3.0 and 6.5; in guinea-pig and rabbit 101 and 106. 2. 2. Activity with d-pipecolic acid was consistently 50–60% higher than the l-isomer except in the rabbit. 3. 3. Degradation of l-lysine, presumably through the saccharopine-α-aminoadipic acid pathway, was effective in all species, contrasting with the variable performance in the pipecolic acid-α-aminoadipic acid pathway.

Accumulation and metabolism of pipecolic acid in the brain and other organs of the mouse.

The long-term accumulation of pipecolic acid, as well as its disappearance following exogenous administration was studied in brain and other organs of the mouse. Mice were pulse-injected intraperitoneally or intravenously with 1μCi[3H]D,l-pipecolic acid (6.9 nmol/mouse=2.9 μg/kg). The total radioactivity retained in tissues was measured in brain, liver, and kidney, as well as in plasma during the period 1 min to 24 hr. TLC separation of DNP-derivatives was performed. Three features of the pattern of retention of pipecolic acid are most salient; first the rapid accumulation in brain, second the rapid secretion of this compound in the urine, and third the long-lasting steady levels of radioactivity maintained in brain.

Lysine and pipecolic acid metabolism in the rumen. IV. Catabolism of lysine by mixed rumen bacteria.

Metabolites arising from the catabolism of lysine by the mixed rumen bacteria were chromatographically examined by using radioactive lysine. After 6 hr incubation, 241 nmole/ ml of lysine was decomposed to give ether-soluble substances and CO2 by the bacteria and 90 nmole/ml of lysine was incorporated unchanged into the bacteria. δ-Aminovalerate, cadaverine or pipecolate did not seem to be produced from lysine even after incubation of the bacteria with addition of those three amino compounds to trap besides lysine and radioactive lysine. Most of the ether-soluble substances produced from radioactive lysine was volatile fatty acids (VFAs). Fractionation of VFAs revealed that the peaks of butyric and acetic acids coincided with the strong radioactive peaks. Small amounts of radioactivities were detected in propionic acid peak and a peak assumed to be caproic acid. The rumen bacteria appeared to decompose much larger amounts of lysine than the rumen ciliate protozoa did.

Lysine and Pipecolic Acid Metabolism in the Domestic Fowl

SummaryExperiments were conducted with colostomized adult Leghorn pullets to determine the urinary excretion products produced from the metabolism of d- and l-lysine and l–pipecolic acid. The results indicate that the fowl, unlike the rat, excretes very little free pipecolic acid after an intraperitoneal dose of either d-lysine or l-pipecolate. The urine was analyzed for an ornithine conjugate of pipecolic acid or a degradation product of lysine metabolism. None was detected. It was concluded that the increase in the chicken's requirement for arginine when surfeit lysine is consumed is not due to a need for ornithine to detoxify a lysine metabolite.

Metabolism of pipecolic acid in a Pseudomonas species. V. Pipecolate oxidase and dehydrogenase.

Oxidation of pipecolate to Delta(1)-piperideine-6-carboxylate is catalyzed by pipecolate oxidase, an inducible, membrane-bound dehydrogenase associated with the electron transport components of Pseudomonas putida P2. From the oxidase, we obtained a smaller particle containing flavine adenine dinucleotide (FAD) and cytochrome b, but no longer able to catalyze electron transfer to oxygen or to cytochrome c. Certain properties of this l-pipecolate dehydrogenase, an FAD-flavoprotein, are reported.

Metabolism of Pipecolic Acid in a Pseudomonas Species IV. Electron Transport Particle of Pseudomonas putida

Baginsky, Marietta L. (University of California, San Francisco Medical Center, San Francisco), and Victor W. Rodwell. Metabolism of pipecolic acid in a Pseudomonas species. IV. Electron transport particle of Pseudomonas putida. J. Bacteriol. 92:424-432. 1966.-Enzymes of Pseudomonas putida P2 catalyzing oxidation of pipecolate to Delta(1)-piperideine-6-carboxylate are located in a subcellular fraction sedimenting at 105,000 x g. Since this fraction resembles the mammalian electron transport particle in both chemical composition and enzymatic activities, it was termed Pseudomonas P2 electron transport particle (P2-ETP). P2-ETP contains flavin adenine dinucleotide, flavin mononucleotide, iron, copper, and both b- and c-type cytochromes. The reduced type b cytochrome has absorption maxima at 558 to 559, 530, and 427 mmu. Its oxidized pyridine hemochromogen has an absorption maximum at 406 mmu, with a shoulder at 564 mmu. On dithionite reduction, absorption bands with maxima at 556, 522, and 418 mmu are obtained. The reduced type c cytochrome has absorption maxima at 552, 520, and 422 mmu; its reduced pyridine hemochromogen has maxima at 551, 516 to 519, and 418 mmu. No type a cytochrome was detected. P2-ETP catalyzes oxidation of pipecolate and of reduced nicotinamide adenine dinucleotide (NADH(2)) by oxygen. It can also oxidize these compounds, as well as succinate and reduced nicotinamide adenine dinucleotide phosphate, with 2,6-dichlorophenol-indophenol as electron acceptor. Mammalian cytochrome c can be used as an alternate artificial electron acceptor for the oxidation of pipecolate and succinate, but not for oxidation of NADH(2).