Catalase from Candida boidinii 2201.
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Biomedical subjects
Publications and source records attributed to S Mozaffar.
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A clone harbouring the genomic DNA sequence for the peroxisomal catalase of an n-alkane-utilizable yeast, Candida tropicalis, has been isolated by the hybrid-selection method and confirmed with a probe of catalase partial cDNA. Nucleotide sequence analysis of the cloned DNA disclosed that the gene fragment coding for catalase had a length of 1455 base pairs (corresponding to 485 amino acids; m = 54937 Da), and that the size of this enzyme was the smallest among all catalases reported hitherto. No intervening sequence was found in this coding region and some portions coincided with the amino acid sequences obtained from the analysis of the purified catalase. The comparison with three peroxisomal catalases from rat liver, bovine liver and human kidney, and one cytosolic catalase from Saccharomyces cerevisiae has revealed that catalase from C. tropicalis was more homologous to the peroxisomal enzymes than to the cytosolic one. C. tropicalis used the codons of the high-expression type. Amino acid residues were all conserved at the active and heme-binding sites. In the N and C-terminal regions there was no characteristic signal sequence or consensus sequence. However, a noticeable region, which can be discriminated between peroxisomal and cytosolic catalases, was proposed.
Catalase, a marker enzyme of peroxisomes, was purified to homogeneity from whole cells of Kloeckera sp. 2201 (a strain of Candida boidinii) grown on methanol by means of ammonium sulfate fractionation followed by hydroxyapatite, Sephacryl S-300 and DEAE-Sepharose column chromatographies. Crystallized catalase was brown-coloured and needle-like. The molecular mass of the enzyme was about 240 000 daltons consisting of four identical subunits of 62 000 daltons. The minimum size of catalase molecule was estimated to be about 6 X 10 nm from an electron micrograph. Judging from the absorption spectrum, the enzyme seemed to belong to a group of T-type catalase. The Km value of the enzyme for hydrogen peroxide (catalatic activity) was 25 mM, while that for methanol (peroxidatic activity) was 83 mM. Catalase from Kloeckera sp. cells showed a certain degree of similarity to the enzyme purified from alkane-grown Candida tropicalis [T. Yamada et al. (1982) Eur. J. Biochem. 125, 517-521 and 129, 251-255] in its immunochemical properties.