Isolation, properties, and regulation of a mitochondrial acyl coenzyme A thioesterase from pig heart.
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Biomedical subjects
Publications and source records attributed to H Schulz.
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A 66-year-old patient with 48-hour unipolar-depressive cycles was studied in the hospital for one month and in an isolation unit for two weeks. At 3-hour intervals during the day and once at night the mood state was assessed by two self-rating scales and urine was collected for the determination of urinary free cortisol (UFC). In the hospital there was a regular alternation between 'good' and 'bad' days. Without exception the switch from normal to depressive mood occurred between 22:00 and 2:30, when the patient was sleeping. The switch from depressive to good mood was variable and occurred in the late morning or in the afternoon. On a 24-hour basis a highly significant correlation was seen between the mood state and the UFC excretion: r = 0.73, P less than 0.001 (hospital); r = 0.82, P less than 0.01 (isolation unit). The shape of the 24-hour profile for the UFC excretion was similar on good and bad days, with a maximum between 2:30 and 7:00 and a minimum between 19:00 and 2:30. However, on bad days UFC was elevated at all clock times. A decrease in adrenal cortical activity preceded or was parallel to substantial improvement in the mood state. Internal desynchronization occurred in the isolation unit but not in the hospital, with a rest-activity period of 18.6 h and a period close to 24 h for UFC excretion. Changes in mood were associated with both cycles, and a very close link between the switch from normal to depressive mood and the sleep state could be demonstrated.
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The purified multienzyme complex of fatty acid oxidation from Escherichia coli was found to possess 3-hydroxyacyl-coenzyme A (CoA) epimerase and cis-delta3-trans-delta2-enoyl-CoA isomerase activities in addition to the previously identified enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and 3-ketoactyl-CoA thiolase activities. Evidence is presented in support of the proposed association of all five enzyme activities with one protein which apparently is composed of two types of subunits and which can exist in several aggregated forms. The five component enzymes of the complex were rapidly inactivated by tris(hydroxymethyl)aminomethane, whereas they remained active in the presence of potassium phosphate.
The REM sleep latency of endogenously depressed patients was investigated by analyzing 90 polysomnograms of six patients during depression and 58 polysomnograms of four of these patients after remission. During depression the REM sleep latencies are distributed bimodally with peaks at sleep onset (sleep onset REM phases, SOREMPs) and 60 min later. During the follow-up examinations some time after remission, the occurrence of SOREMPs is very rare. A model is proposed according to which the occurrence of SOREMPs in the sleep of these patients is caused by a reduced amplitude of the circadian rhythm of the arousal system.
Sleep-wake cycles are closely tied with the circadian period of other bodily functions. Optimal synchronization is essential for troublefree alterations of sleep and wake periods. The neurophysiologic control areas are in various of the brain are far apart from each other for which reason a great variety of possible causes for sleep difficulties do exist. It has been shown recently that spezific mono-aminergic and cholinergic systems in the brain stem do control sleep. A case study will show that it is possible to improve sleeping difficulties with the serotonin precursor L-Troyptophan.
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Sleep disturbances, which are a prominent symptom of depressive illness, were analyzed in endogenously depressed patients during depression and during full remission. These disturbances may be described at the level of sleep stages, at the level of the sleep profile, and at the level of consecutive sleep records. The scoring of sleep stages in sleep records of depressive patients provides difficulties, because the temporal coherence of different electrophysiological descriptors of sleep is weakened during depression. The sleep profile of depressed patients is characterized by alterations in the normal sequence of sleep stages and frequent stage changes. The disturbances in the sleep profile are unstable in that they show marked day to day fluctuations. It could be shown in some patients that there is a correlation between parameters of the first REM sleep and urinary free cortisol excretion in corresponding nights.
A thiolase (acetyl CoA acyltransferase, EC 2.3-1.16) which acts on substrates of various chain lengths (thiolase I) has been purified from pig heart muscle 366-fold to near homogeneity as judged by gel electrophoresis. Its molecular weight was estimated to be 200,000 in the absence and 46,000 in the presence of sodium dodecyl sulfate. Kinetic measurements with acetoacetyl coenzyme A, 3-ketohexanoyl-CoA, 3-ketooctanoyl-CoA, and 3-ketodecanoyl-CoA yielded apparent Km values of 16, 8.3, 2.4, and 1.8 micron, respectively, whereas apparent Vmax values of 65 to 69 mumol/min/mg were obtained with all substrates except for acetoacetyl-CoA, with which a value of 26.5 mumol/min/mg was observed. Antibodies prepared against this thiolase were used to demonstrate that thiolase I and acetoacetyl-CoA thilase (thiolase II) from pig heart mitochondria are immunologically unrelated. The antibodies cross-reacted, however, with thiolase I from beef heart. Kinetic constants (Km, Vmax) were also determined for thiolases I and II from Escherichia coli, as were the native and subunit molecular weights of E. coli thiolase II. Although the E. coli thiolases were found to be immunologically distinct from the pig heart enzymes, their physical and kinetic properties are strikingly similar to those of the heart thiolases. In view of this finding and in view of the known physiological functions of the E. coli thiolases, it is proposed that thiolase I from pig heart is only involved in fatty acid metabolism, whereas thiolase II functions solely in ketone body degradation.
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The influence of 500 microunits oxytocin as well as 50 micrunits lysine-vasopressin on hypothalamic self-stimulation rate after intraventricular application was studied. Oxytocin caused an increase and vasopressin a decrease in the self-stimulation rate.
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A short chain enoyl-CoA hydratase (crotonase) from pig heart has been purified to apparent homogeneity. The enzyme has an estimated native molecular weight of 155,000 and appears to be composed of six subunits of molecular weight 27,300. A study of the kinetic properties of the enzyme revealed that the maximal velocity decreases nearly linearly with increasing chain length of the substrates from 1,670 units/mg with crotonyl-CoA to 40 units/mg with hexadecenoyl-CoA. However, the same Km values of 30 muM were obtained for all substrates except for crotonyl-CoA for which a value of 13 muM was determined. Since the presence of both crotonase and long chain enoyl-CoA hydratase in pig heart has been reported earlier, the presence of the same two enoyl-CoA hydratases in various tissues of several animals was investigated by sequential extraction and chromatography on hydroxylapatite of tissue homogenates. The simultaneous occurrence of both types of enoyl-CoA hydratase in tissues of pig and guinea pig has thus been established. It is proposed that the complementary actions of the two enoyl-CoA hydratases assures a high rate of hydration of enoyl-CoA intermediates of all chain lengths in fatty acid oxidation.
Polygraphic examinations were made during the day on 6 normal subjects. Simultaneous evaluation of EEG, EOG and EMG was carried out over 30 sec epochs. The data thus obtained were correlated with the various types of behaviour and activities during the day and then interpreted. Six conditions could be defined corresponding to different waking stages. The analysis of the material obtained shows that the existence of these waking stages is of interindividual validity.
A multi-enzyme complex of fatty acid oxidation has been isolated from E. coli B cells and has been purified to near homogeneity by a simple two-step procedure. The complex exhibits thiolase (EC 2.3.1.9), enoyl-CoA hydratase (EC 4.2.1.17), and 3-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35) activities towards short-, medium-, and long-chain substrates. The complex has been estimated to have a molecular weight of approximately 300,000 and is apparently composed of two types of subunits with molecular weights of 78,000 and 42,000.
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