Abstract
Two isozymes of aspartate aminotransferase have been demonstrated biochemically. One isozyme is found in the mitochondrial fraction of the cytoplasm, the other ("soluble") in the supernatant. Both isozymes can be demonstrated by the cytochemical technique of Lee and Torack, as reported in the preceding report. Aldehyde fixation rapidly inactivates both isozymes, especially the soluble one. Inactivation can be delayed by addition of ketoglutarate to the fixative. The ketoglutarate probably competes with the fixative for the active site of the enzyme, thus protecting that region of the molecule. This enables adequate tissue preservation with enough remaining enzymatic activity to be demonstrated by the precipitation of oxaloacetate as the lead salt from a medium containing α-ketoglutaric acid aspartic acid, and lead nitrate. Electron-opaque material was found not only in mitochondria but, as the result of substrate protection, on the plasma membranes of many cells including erythrocytes and bacteria, the limiting membrane of peroxisomes, and the transverse tubular system of striated muscle. Occasional centrioles, neurotubules, tubules in the tails of spermatozoa, the A-I band junction in myofibrils of striated muscle, and the ground substance between cisternae of endoplasmic reticulum in intestinal goblet cells also showed precipitate. In all cases, replacement of L-aspartic acid by D-aspartic acid in the medium resulted in unstained sections. The sensitivity of extramitochondrial sites to fixation, the need of ketoglutarate as an agent for protecting the enzymatic activity during the fixation process, and the known presence of only soluble isozyme in erythrocytes indicate that enzymatic activity at these sites can be attributed to the soluble isozyme. Localization of the soluble isozyme on the plasma membrane may be related to possible involvement in depolarization phenomena, amino acid transport, or synthesis of plasma membrane-bound mucopolysaccharides.
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- BORST P., PEETERS E. M. The intracellular localization of glutamate-oxaloacetate transaminases in heart. Biochim Biophys Acta. 1961 Nov 25;54:188–189. doi: 10.1016/0006-3002(61)90953-2. [DOI] [PubMed] [Google Scholar]
- Baudhuin P., Beaufay H., Rahman-Li Y., Sellinger O. Z., Wattiaux R., Jacques P., De Duve C. Tissue fractionation studies. 17. Intracellular distribution of monoamine oxidase, aspartate aminotransferase, alanine aminotransferase, D-amino acid oxidase and catalase in rat-liver tissue. Biochem J. 1964 Jul;92(1):179–184. doi: 10.1042/bj0920179. [DOI] [PMC free article] [PubMed] [Google Scholar]
- CURTIS D. R. ACTIONS OF DRUGS ON SINGLE NEURONES IN THE SPINAL CORD AND THALAMUS. Br Med Bull. 1965 Jan;21:5–9. doi: 10.1093/oxfordjournals.bmb.a070356. [DOI] [PubMed] [Google Scholar]
- EICHEL H. J., BUKOVSKY J. Intracellular distribution pattern of rat liver glutamic-oxalacetic transaminase. Nature. 1961 Jul 15;191:243–245. doi: 10.1038/191243a0. [DOI] [PubMed] [Google Scholar]
- FLEISHER G. A., POTTER C. S., WAKIM K. G. Separation of 2 glutamic-oxalacetic transaminases by paper electrophoresis. Proc Soc Exp Biol Med. 1960 Jan;103:229–231. doi: 10.3181/00379727-103-25469. [DOI] [PubMed] [Google Scholar]
- FLEISHER G. A., WAKIM K. G. Presence of two glutamic-oxalacetic transaminases in serum of dogs following acute injury of the liver. Proc Soc Exp Biol Med. 1961 Feb;106:283–286. doi: 10.3181/00379727-106-26310. [DOI] [PubMed] [Google Scholar]
- Fonnum F. The distribution of glutamate decarboxylase and aspartate transaminase in subcellular fractions of rat and guinea-pig brain. Biochem J. 1968 Jan;106(2):401–412. doi: 10.1042/bj1060401. [DOI] [PMC free article] [PubMed] [Google Scholar]
- GAULL G., VILLEE C. A. Effects of some dicarboxylic acids on succinate oxidation in vitro. Biochim Biophys Acta. 1960 Apr 22;39:560–563. doi: 10.1016/0006-3002(60)90220-1. [DOI] [PubMed] [Google Scholar]
- GIBSON I. M., MCILWAIN H. CONTINUOUS RECORDINGS OF CHANGES IN MEMBRANE POTENTIAL IN MAMMALIAN CEREBRAL TISSUES IN VITRO; RECOVERY AFTER DEPOLARIZATION BY ADDED SUBSTANCES. J Physiol. 1965 Jan;176:261–283. doi: 10.1113/jphysiol.1965.sp007549. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HILLMAN H. H., McILWAIN H. Membrane potentials in mammalian cerebral tissues in vitro: dependence on ionic environment. J Physiol. 1961 Jul;157:263–278. doi: 10.1113/jphysiol.1961.sp006720. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HOLT S. J., O'SULLIVAN D. G. Studies in enzyme cytochemistry I. Principles of cytochemical staining methods. Proc R Soc Lond B Biol Sci. 1958 Apr 8;148(933):465–480. doi: 10.1098/rspb.1958.0039. [DOI] [PubMed] [Google Scholar]
- KORNFELD S., KORNFELD R., NEUFELD E. F., O'BRIEN P. J. THE FEEDBACK CONTROL OF SUGAR NUCLEOTIDE BIOSYNTHESIS IN LIVER. Proc Natl Acad Sci U S A. 1964 Aug;52:371–379. doi: 10.1073/pnas.52.2.371. [DOI] [PMC free article] [PubMed] [Google Scholar]
- KRNJEVIC K., PHILLIS J. W. Iontophoretic studies of neurones in the mammalian cerebral cortex. J Physiol. 1963 Feb;165:274–304. doi: 10.1113/jphysiol.1963.sp007057. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LANG N., MASSARRAT S. IMMUNOLOGIE UND ENZYMKINETIK DER GLUTAMAT-OXALACETAT-TRANSAMINASE (GOT) UND DER GLUTAMAT-PYRUVAT-TRANSAMINASE (GPT) II. UNTERSUCHUNGEN ZUR ISOENZYM-, ORGAN- UND SPECIESSPEZIFITAET. Klin Wochenschr. 1965 Jun 1;43:597–602. doi: 10.1007/BF01879180. [DOI] [PubMed] [Google Scholar]
- Lee S. H. Histochemical demonstration of glutamic oxalacetic transaminase. Am J Clin Pathol. 1968 Apr;49(4):568–572. doi: 10.1093/ajcp/49.4.568. [DOI] [PubMed] [Google Scholar]
- Lee S. H., Torack R. M. A biochemical and histochemical study of glutamic oxalacetic transaminase activity of rat hepatic mitochondria fixed in situ and in vitro. J Cell Biol. 1968 Dec;39(3):725–732. doi: 10.1083/jcb.39.3.725. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lee S. H., Torack R. M. Electron microscope studies of glutamic oxalacetic transaminase in rat liver cell. J Cell Biol. 1968 Dec;39(3):716–724. doi: 10.1083/jcb.39.3.716. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lee S. H. Ultrastructural localization of glutamic oxalacetic transaminase activity in cardiac muscle fiber and cardiac mitochondrial fraction of the rat. Histochemie. 1969;19(2):99–109. doi: 10.1007/BF00281089. [DOI] [PubMed] [Google Scholar]
- Moscona A. A. Cell aggregation: properties of specific cell-ligands and their role in the formation of multicellular systems. Dev Biol. 1968 Sep;18(3):250–277. doi: 10.1016/0012-1606(68)90035-3. [DOI] [PubMed] [Google Scholar]
- Nisselbaum J. S., Bodansky O. Glutamic-Oxaloacetic Transaminases in Reticulocytes and Erythrocytes. Science. 1965 Jul 9;149(3680):195–197. doi: 10.1126/science.149.3680.195. [DOI] [PubMed] [Google Scholar]
- Oppenheimer S. B., Edidin M., Orr C. W., Roseman S. An L-glutamine requirement for intercellular adhesion. Proc Natl Acad Sci U S A. 1969 Aug;63(4):1395–1402. doi: 10.1073/pnas.63.4.1395. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Papadimitriou J. M., van Duijn P. Effects of fixation and substrate protection on the isoenzymes of aspartate aminotransferase studied in a quantitative cytochemical model system. J Cell Biol. 1970 Oct;47(1):71–83. doi: 10.1083/jcb.47.1.71. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schnaitman C., Greenawalt J. W. Enzymatic properties of the inner and outer membranes of rat liver mitochondria. J Cell Biol. 1968 Jul;38(1):158–175. doi: 10.1083/jcb.38.1.158. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stern J. R., Eggleston L. V., Hems R., Krebs H. A. Accumulation of glutamic acid in isolated brain tissue. Biochem J. 1949;44(4):410–418. [PMC free article] [PubMed] [Google Scholar]
- Swick R. W., Stange J. L., Nance S. L., Thomson J. F. The heterogeneous distribution of mitochondrial enzymes in normal rat liver. Biochemistry. 1967 Mar;6(3):737–744. doi: 10.1021/bi00855a013. [DOI] [PubMed] [Google Scholar]
- TAKEUCHI A., TAKEUCHI N. THE EFFECT ON CRAYFISH MUSCLE OF IONTOPHORETICALLY APPLIED GLUTAMATE. J Physiol. 1964 Mar;170:296–317. doi: 10.1113/jphysiol.1964.sp007332. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Teräväinen H. Distribution of acetylcholinesterase in extraocular muscle fibres of the rat. Histochemie. 1969;18(2):174–176. doi: 10.1007/BF00280999. [DOI] [PubMed] [Google Scholar]
- USHERWOOD P. N., GRUNDFEST H. PERIPHERAL INHIBITION IN SKELETAL MUSCLE OF INSECTS. J Neurophysiol. 1965 May;28:497–518. doi: 10.1152/jn.1965.28.3.497. [DOI] [PubMed] [Google Scholar]
- Usherwood P. N., Machili P. Chemical transmission at the insect excitatory neuromuscular synapse. Nature. 1966 May 7;210(5036):634–636. doi: 10.1038/210634a0. [DOI] [PubMed] [Google Scholar]