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In experiments in vivo it was shown that upon low-intensity infrared irradiation changes in the activity of main enzymes of glutamic acid metabolism are a function of time of exposure and flux density.
Protein TT0402 from Thermus thermophilus HB8 exhibits about 30-35% sequence identity with proteins belonging to subgroup IV in the aminotransferase family of the fold-type I pyridoxal 5'-phosphate (PLP)-dependent enzymes. In this study, we determined the crystal structure of TT0402 at 2.3 A resolution (R(factor) = 19.9%, R(free) = 23.6%). The overall structure of TT0402 exhibits the fold conserved in aminotransferases, and is most similar to that of the Escherichia coli phosphoserine aminotransferase, which belongs to subgroup IV but shares as little as 13% sequence identity with TT0402. Kinetic assays confirmed that TT0402 has higher transamination activities with the amino group donor, L-glutamate, and somewhat lower activities with L-aspartate. These results indicate that TT0402 is a subgroup IV aminotransferase for the synthesis/degradation of either L-aspartate or a similar compound.
We report a case of unexplained and persistently elevated ASAT activity in serum. This appeared to be due to a macro-enzyme of ASAT, as was demonstrated by protein-A-Sepharose treatment of the serum sample. Although macro-ASAT seems to be clinically irrelevant, unexplained raised ASAT activity without acknowledgement of its macroenzyme nature may lead to unnecessary diagnostic procedures.
Scheme of apricot AAT control by Aat-1, Aat-2, Aat-3 loci on the base of formal genetic analysis was created. Determination by three active (a, b, c) and null (n) alleles Aat-1 of interspecies polymorphism of fast migrating components was revealed. Alleles frequencies and heterozygosity of Aat-1 locus were determined in ecologic-geographical groups of apricot as well as varieties of hybrid origin.
Pulse-modulated microwaves (frequency 2375 MHz, intensity: 2 microW/cm2 and 8 microW/cm2, pulse modulation from 50 to 390 Hz with step of 20 Hz; exposure time 5 min) changed the activity of aspartataminotranspherase of the donor blood. Aspartataminotranspherase activity was strongly dependent both on modulation frequency and microwave intensity. Maximum activity was found at 390 Hz and 8 microW/cm2. Maximum observed activity was about six times greater than control level of activity.
It is important that recommendations of expert bodies for the estimation of enzymes are not undermined by laboratories at District General Hospital level adopting manufacturers' procedures. Three enzyme assay methods are presented which enable adaptation of SCE kinetic methods to the end point type of determination performed on the Vickers SP120 continuous flow analyser. Despite the differences in analytical principle, good precision and correlation was obtained.
In order to obtain an enriched fraction of mRNA for mAAT we applied the following method: preparation of cytoplasmic polysomes; isolation of total RNA; isolation of mRNA by chromatography on oligo(dT)-cellulose column; polyacrylamide gel electrophoresis; extraction of mRNA from the gel. The procedure seems to allow isolation of mRNA enriched fraction for mAAT. An enriched fraction of mRNAs can be useful for the preparation of corresponding cDNAs.
Immunocytochemical and histoenzymological were used to determine the localization and activity of AATase respectively at light and electron microscopic levels. Ths histoenzymological method revealed AATase activity in synaptic vesicles and in mitochondria. Both methods detected AATase presence and activity in pre and post-synaptic sites. No simultaneous positive reaction was observed at pre and post-synaptic zones of a given synapses. The significance of these results are discussed in the present paper.
The theoretical conformational analysis of the pyridoxal-5'-phosphate aldimine complex with a substrate analogue--threo-alpha-cycloglutamic acid has been carried out. The calculation method used takes into account the possibility of hydrogen bonding between a carboxyl group of the substrate and the phosphate moiety of the cofactor. The conformational properties and geometrical parameters of the lowest energy structures are discussed. It is shown that of the three conformations permitted for the productive enzyme--substrate complex formations only one is electrostatically favourable.
Hydrocortisone and ACTH administration induced AlT- and AsT-activity changes in the brain hemispheres, liver, spleen, muscles and blood plasm of rabbits. The direction and rate of changes of the studied enzymes activity in the tissues was not the same after hydrocortisone and ACTH injections and depended on duration of the hormones administration. The changes in the AlT-activity were more essential than those in the AsT-activity for all tissues.
On the basis of examinations of altogether 197 patients the results of the changes of GOT and GPT were compared with the old and new colour tests of the AWD Dresden in normal histology, virus hepatitis, fatty liver, liver cirrhosis and posthepatic occlusion. Though the new colour test reveals a higher sensitivity, the differential diagnosis between selected liver diseases, especially virus hepatitis and posthepatic occlusion syndrome have become more difficult. The cause for this is the less significant separability between the individual regions of reference.
The localization of both cAATase activity, by histoenzymological method, and the immunoreactivity against cAATase, were investigated in the cochlear nucleus of rats. The immunohistochemical determination of cAATase was carried out using the PAP method, with an antiserum obtained from rabbits immunized with porcine cAATase. It was also studied both the immunolocalization of GABA-like and GAD-like substances. Our observations, with light microscope, revealed weak cAATase activity in the small neurons, and a more intense one in the fibers surrounding neuronal bodies. The large neurons presented a very weakly activity within their neuronal bodies and dendrites, but it was strongly found in granulations that surround the perikaryon and dendrites. cAATase immunoreactivity presents the same distribution as the enzymological activity. In the same way, we have investigated the pattern of distribution of both GABA- and GAD-like substances. Immunolocalization of these substances was similar to that found for cAATase. In the control sections incubated with Gostatin (0.05 mM), cAATase activity was absent. The immunoreactivity was also negative in every immunohistochemical control sections. These facts suggest that aspartate could intervene as a co-neurotransmitter or neuromodulator in the rat cochlear nucleus, and that axonic endings could contain cAATase, GABA and GAD. It was also found immunoreactivity against cAATase, GABA and GAD, in neuronal bodies, dendrites and glial processes, in close association with capillary wall. These observations have led us to suggest the possible co-localization and co-release of both GABA and aspartate from synaptic and non-synaptic sites in the cochlear nucleus.
With regard to adding Pyridoxal Phosphate (PALP), which combines with the active sites of AST and ALT, JSCC recommends measuring holoenzymes without adding PALP, reflecting the biological reaction. On the other hand, IFCC recommends the measurement of both holoenzymes and apoenzymes when PALP is added, reflecting the total diverted from the internal organs. It is important which recommendation to follow from a clinical point of view and from the viewpoint of reducing gaps in clinical facilities. Further, it is necessary to consider each isozyme as well as the time difference between apoenzyme and holoenzyme diversion from blood to accurately grasp the pathology and understand the measurement.
The site of synthesis of the higher molecular weight precursor of mAAT has been determined by separation of free and membrane-bound polysomes. Free and bound polysomes were isolated from rat liver and the polyA+RNA was extracted. Protein synthesis was carried out for two hours by using a reticulocyte lysate system in the presence of 35S-methionine. The samples were subjected to immunoprecipitation with specific antiserum. The precipitates were analyzed by Na-DodSO4/polyacrylamide gel electrophoresis and fluorography. The results clearly demonstrate that the enzyme is synthesized by free polysomes.
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AST levels from 11 untreated children with T-ALL were found to be significantly higher than those from 74 children with non-T disease. The enzyme was not related to haemoglobin or bilirubin levels nor to the presence of hepatosplenomegaly in any of the patients. It was correlated with the white cell count, but only in the T-cell group and not the remainder. It was also correlated with a parallel (but lesser) rise in ALT, but again only in the T-cell group. The blast cells themselves contained little or no transaminase activity, so it is probable that T-ALL produces more extramedullary tissue damage than non-T disease.
The study sought to establish a relationship between the AST isoenzyme levels in serum and degree of hepatic damage, by using a new and simple immunochemical method for the differential determination of the isoenzymes. Sixty-nine patients with various hepatic diseases were studied. During hepatic damage, cytoplasmic isoenzyme (s-AST) is found in greater quantities than mitochondrial isoenzyme (m-AST), but the m-AST level increases to a greater extent in acute liver diseases. However, m-AST in alcoholic hepatitis is higher than expected from the total AST (t-AST) values. The ratio of m-AST to t-AST seems to discriminate alcoholic hepatitis from other liver diseases.
The Authors have studied AST and ALT enzymatic activities in the workers of two firms, the former of which (tannery) with a high and the latter (boot and shoe factory) with a low level of hepatic-toxic risk. The influence of various trouble factors such as age, sex and seniority was eliminated through appropriate statistical techniques. A significant difference was evidenced between AST and ALT levels in two firms, chiefly attributable to the quantity and quality of the substances utilized in the two technological cycles: trichloroethylene, chromium, sulphuric acid, mineral oils, ammonia, N-hexane, pentanes acetone, ciclo hexane, methanol, ethyl acetate, isopropyl acetate, toluene, methylene chloride.