| First Author | Walker T | Year | 1996 |
| Journal | Mouse Genome | Volume | 94 |
| Issue | 1 | Pages | 149-51 |
| Mgi Jnum | J:32142 | Mgi Id | MGI:79646 |
| Citation | Walker T, et al. (1996) Methylglyoxal dehydrogenase (EC 1.2.1.23): No enzyme detection in mouse inbred strains. Mouse Genome 94(1):149-51 |
| abstractText | Full text of Mouse Genome contribution: METHYLGLYOXAL DEHYDROGENASE (EC 1.2.1.23): NO ENZYME DETECTION IN MOUSE INBRED STRAINS. T. Walker1, K. Bender1 and H. Mossmann2; 1Institut fur Humangenetik und Anthropologie der Universitat Freiburg Breisacher Str. 33, D - 79106 Freiburg, FRG; 2Max-Planck-Institut fur Immunbiologie Freiburg, Stubeweg 51, D - 79108 Freiburg, FRG Methylglyoxal is a noxious but unavoidable by-product of glycolysis and of a number of other metabolic pathways (4, 5). It is effectively eliminated by the glyoxalase system, with D-lactate as the major end product. D-lactate is poorly utilized by higher organisms and mostly excreted in the urine. Monder (3) detected an alpha-ketoaldehyde dehydrogenase in sheep and rat liver which directly oxidizes methylglyoxal into the physiologically important pyruvic acid. The enzyme was later called methylglyoxal dehydrogenase (Mgd; EC 1.2.1.23). Bender et al. (1) reported on a biochemical Mgd polymorphism in the laboratory rat which showed that rat inbred strains have fixed either allele Mgdla (expressing a fast anodal enzyme band) or allele Mgdlb (expressing a slow anodal band). Fl animals showed a five-banded enzyme pattern, indicating a tetrameric enzyme structure. The Mgdl gene was mapped in close linkage with Pep3 (peptidase 3) and Fhl (fumarate hydratase 1) to rat chromosome 13 within a synteny group homologous with mouse chromosome 1 (2). We have now analyzed a number of additional mammalian species, amongst them the seven mouse inbred strains AKR/N, BALB/cNHan, CBA/J, C3H/fTif, C57BL/6Han, DBA/2JHan, SJL/J, the outbred strain NMRI/Han and the Fl (BALB/c x C57BL/6) hybrid line, all maintained at the Max-Planck-Institut fur Immunbiologie Freiburg, Germany. Homogenates of liver, kidney, lung and heart were tested for their Mgd1 phenotypes after starch gel electrophoresis using a Tris/citric acid buffer system, pH 7.2, and an enzyme detection assay consisting of 500 ul methylglyoxal, 15 mg NAD, 10 mg MTT, 1 mg PMS, dissolved in 15ml phosphate buffer, pH 6.8 (1). The results are shown in Figures 1a/1b, where liver zymograms of various mammalian species (humans, cattle, pigs, mice and rats) are compared side-by-side, using a methylglyoxal-free (Fig. la) and in parallel, a methylglyoxal-containing staining assay (Fig. lb). At first sight the patterns seem rather complex. However, the gel buffer included citric acid; thus the typical isocitrate dehydrogenase isozymes were also detectable, with the cytoplasmic Idh 1 bands at the anode and the mitochondrial Idh2 bands predominantly at the cathode (both marked by rectangular bands in the diagrams of Figures la and lb). The well-known murine IDH1 phenotypes (IDH1 B in BALB/c, lane 8; IDH1 A in AKR, lane 9) can also be differentiated. Whereas the methylglyoxal-free staining assay only allowed the detection of the isocitrate dehydrogenases (Fig. la), the full-staining assay with methylglyoxal resulted in a drastic reduction in the Idh zone intensities. In an addition, a prominent anodal enzyme fraction (marked by oval bands in Figure lb) was observed in humans, bovines, pigs and (at even two different electrophoretic positions) rats, representing the methylglyoxal dehydrogenase, Mgdl . No Mgdl activity zone, however, was detectable in all the mouse lines under study. Fig. 1: (Legend). Diagrammatic presentation of liver zymograms from three human (lane 1-3), two cattle (4-5), two pig (6-7), mouse BALB/cHan (8), mouse AKR/N (9), and three inbred rat strain (10-12) samples, separated by starch gel electrophoresis in a citric acid-containing gel buffer. a) Gel stained with a methylglyoxal-free detection assay: only the isocitrate dehydrogenase (Idh) zones are visible; Idh-1 at the anode, Idh-2 predominantly at the cathode (both Idh zones marked by rectangular bands). b) Same as a) gel, but stained with a methylglyoxal-containing assay: besides a drastic reduction in the rectangularly marked Idh bands, an additional anodal zone is visible (marked by oval-shaped bands) in humans, cattle, pigs, and rats, which represents the methylglyoxal dehydrogenase (Mgdl). No Mgdl activity was detected in the mouse strains. The physiological significance of methylglyoxal dehydrogenase, which in contrast to the ubiquitous glyoxalase system is restricted only to liver and kidney, has not yet been explored. Its apparent absence from the mouse might be helpful for the further explanation. References 1. Bender, K., Seibert, R.T., Wienker, T.F., Kren, V., Pravenec, M., and Bissbort, S. (1994). Biochem. Genet. 32:147. 2. Levan, G., Szpirer, J., Szpirer, C., Klinga, K., Hanson, C., and Islam, M.Q. (1991) Genomics 10:699. 3. Monder, C. (1967) J. Biol. Chem. 242:4653. 4. Richard, J.P. (1993) Biochem. Soc. Trans. 21:549. 5. Phillips, S.A. and Thornalley, P.J. (1993) Eur. J. Biochem. 212:101. |
