• Racemase;
  • branched-chain fatty acids;
  • peroxisomes;
  • bile acids


  1. Top of page
  2. Abstract
  3. References

A specific racemase for α-methylacyl-CoAs, which had previously been studied in rat liver [W. Schmitz, R. Fingerhut, E. Conzelmann (1994) Eur. J. Biochem. 222, 313–323], has now been demonstrated also in human tissues. The human enzyme cross-reacts with a polyclonal antiserum against the rat liver racemase. The racemase was purified from human liver some 3600-fold. It is a monomer of 47 kDa with an isolectric point of pH 6.1 and is optimally active between pH 7–8. It acts only on coenzyme A thioesters, not on free fatty acids, and accepts as substrates a wide range of α-methylacyl-CoAs, including pristanoyl-CoA and trihydroxycoprostanoyl-CoA (an intermediate in bile acid synthesis), but neither 3-methyl-branched nor linear-chain acyl-CoAs. A clear difference in subcellular localization of the enzyme was found between humans and rats: the rat enzyme co-distributed exclusively with mitochondrial marker enzymes whereas in human cells, only 10–30% of the activity was found in mitochondria, the bulk activity was located in peroxisomes. Cells from patients with general deficiency of peroxisome assembly (Zellweger syndrome) showed strongly reduced racemase activity, with only the mitochondrial share being present while the peroxisomal form was absent.


trihydroxycoprostanoic acid, 5β-(3α,7α,12α-trihydroxy)-26-cholanic acid


Tris-buffered saline (150 mM NaCl, 50 mM Tris/HCl, pH7.5)


sodium/potassium phosphate buffer


  1. Top of page
  2. Abstract
  3. References
  • Ackman, R. G. & Hansen, R. P. (1967) The occurrence of diastereomers of phytanic and pristanic acids and their determination by gas-liquid chromatography, Lipids 2, 357362.
  • Avigan, J., Steinberg, D., Gutman, A., Mize, C. E. & Milne, G. W. A. (1966) α-Decarboxylation, an important pathway for degradation of phytanic acid in animals, Biochem. Biophys. Res. Commun. 24, 838844.
  • Banerjee, A., Burg, J., Conzelmann, E., Carroll, M. & Sandhoff, K. (1984) Enzyme-linked immunosorbent assay for the ganglioside GM2 activator protein – Screening of normal human tissues and body fluids, of tissues of GM2 gangliosidosis, and for its subcellular localization, Hoppe-Seyler's Z. Physiol. Chem. 365, 347356.
  • Bradford, M. M. (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding, Anal. Biochem. 72, 248254.
  • Danpure, C. J., Guttridge, K. M., Fryer, P., Jennings, P. R., Allsop, J. & Purdue, E. (1990) Subcellular distribution of hepatic alanine:glyoxylate aminotransferase in various mammalian species, J. Cell Sci. 97, 669678.
  • Fingerhut, R., Schmitz, W. & Conzelmann, E. (1993) Accumulation of phytanic acid α-oxidation intermediates in Zellweger fibroblasts, J. Inher. Metab. Dis. 16, 591594.
  • Hansen, R. P. & Morrison, J. D. (1964) The isolation and identification of 2,6,10,14-tetramethylpentadecanoic acid from butterfat, Biochem. J. 93, 225229.
  • Hübl, P. & Bretschneider, R. (1964) Titanyl sulfate method for the detection of catalase in blood, serum and urine, Hoppe-Seyler's Z. Physiol. Chem. 335, 146155.
  • Kase, B. F. (1989) Role of liver peroxisomes in bile acid formation: Inborn error of C27-steroid side chain cleavage in peroxisome deficiency (Zellweger syndrome), Scand. J. Clin. Lab. Invest. 49, 110.
  • Laemmli, U. K. (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4, Nature 227, 680685.
  • Noguchi, T. & Takada, Y. (1979) Peroxisomal localization of alanine: glyoxylate aminotransferase in human liver, Arch. Biochem. Biophys. 196, 645647.
  • Noguchi, T., Minatogawa, Y., Takada, Y., Okuno, E. & Kido, R. (1978) Subcellular distribution of pyruvate (glyoxylate) aminotransferases in rat liver, Biochem. J. 170, 173175.
  • Oda, T., Funai, T. & Ichiyama, A. (1990) Generation from a single gene of two mRNAs that encode the mitochondrial and peroxisomal serine:pyruvate aminotransferase of rat liver, J. Biol. Chem. 265, 75137519.
  • Okuno, E., Minatogawa, Y., Nakanishi, J., Nakamura, M., Kamoda, N., Makino, M. & Kido, R. (1979) The subcellular distribution of alanine-glyoxylate aminotransferase and serine-pyruvate aminotransferase in dog liver, Biochem. J. 182, 877879.
  • Poulos, A., Sharp, P. & Whiting, M. (1984) Infantile Refsum's disease (phytanic acid storage disease): a variant of Zellweger's syndrome Clin. Genet. 25, 579586.
  • Poulos, A., Sharp, P., Fellenberg, A. J. & Johnson, D. W. (1988) Accumulation of pristanic acid (2,6,10,14-tetramethylpentadecanoic acid) in the plasma of patients with generalized peroxisomal dysfunction, Eur. J. Pediatr. 147, 143147.
  • Purdue, P. E., Lumb, M. J. & Danpure, C. J. (1992) Molecular evolution of alanine/glyoxylate aminotransferase 1 intracellular targeting. Analysis of the marmosel- and rabbit genes, Eur. J. Biochem 207, 757766.
  • Rhead, W. J., Hall, C. L. & Tanaka, K. (1981) Novel tritium release assays for isovaleryl-CoA and butyryl-CoA dehydrogenases, J. Biol. Chem. 256, 16161624.
  • Schmitz, W., Fingerhut, R. & Conzelmann, E. (1994) Purification and properties of an α-methylacyl-CoA racemase from rat liver, Eur. J. Biochem. 222, 313323.
  • Shefer, S., Cheng, F. W., Batta, A. K., Dayal, B., Tint, G. S., Salen, G. & Mosbach, E. H. (1978) Stereospecific side-chain hydroxylations in the biosynthesis of chenodeoxycholic acid, J. Biol. Chem. 253, 63866392.
  • Singh, H., Usher, S., Johnson, D. & Poulos, A. (1990) A comparative study of straight chain and branched chain fatty acid oxidation in skin fibroblasts from patients with peroxisomal disorders, J. Lipid Res. 31, 217225.
  • Steinberg, D. (1989) Refsum disease, in The metabolic basis of inherited disease, 6th edn (Scriver, C. R., Beaudet, A. L., Sly, W. S. & Valle, D., eds) pp. 15331550, McGraw-Hill, New York .
  • Suzuki, T., Yoshida, T. & Tuboi, S. (1992) Evidence that rat liver mitochondrial and cytosolic fumarases are synthesized from one species of mRNA by alternative translational initiation at two in-phase AUG codons, Eur. J. Biochem. 207, 767772.
  • Swell, L., Gustafsson, J., Danielsson, H., Schwartz, C. C. & Vlahcevic, Z. R. (1981) Biosynthesis of bile acids in man, J. Biol. Chem. 256, 912916.
  • Takada, Y. & Noguchi, T. (1982) Subcellular distribution and physical and immunological properties of hepatic alanine:glyoxylate aminotransferase isoenzymes in different mammalian species, Comp. Biochem. Physiol. 72B, 597604.
  • Takada, Y., Kaneko, N., Esumi, H., Purdue, P. E. & Danpure, C. J. (1990) Human peroxisomal L-alanine:glyoxylate aminotransferase. Evolutionary loss of a mitochondrial targeting signal by point mutation of the initiation codon, Biochem. J. 268, 517520.
  • Une, M., Tazawa, Y., Tada, K. & Hoshita, T. (1987) Occurrence of both (25R)- and (25S)-3α,7α,12α-trihydroxy-5β-cholestanoic acids in urine from an infant with Zellweger's syndrome, J. Biochem. (Tokyo) 102, 15251530.
  • Watkins, P. A., Chen, W. W., Harris, C. J., Hoefler, G., Hoefler, S., Blake, D. C. Jr, Balfe, A., Kelley, R. I., Moser, A. B., Beard, M. E. & Moser, H. W. (1989) Peroxisomal bifunctional enzyme deficiency, J. Clin. Invest. 83, 771777.
  • Yokota, S., Oda, T. & Ichiyama, A. (1987) Immunocytochemical localization of serine: pyruvate aminotransferase in peroxisomes of the human liver parenchymal cells, Histochemistry 87, 601606.