Abstract
L-Methionine decarboxylase (MetDC) from Streptomyces sp. 590 depends on pyridoxal 5′-phosphate and catalyzes the non-oxidative decarboxylation of L-methionine to produce 3-methylthiopropylamine and carbon dioxide. MetDC gene (mdc) was determined to consist of 1,674 bp encoding 557 amino acids, and the amino acid sequence is similar to that of L-histidine decarboxylases and L-valine decarboxylases from Streptomyces sp. strains. The mdc gene was cloned and recombinant MetDC was heterologously expressed by Escherichia coli. The purification of recombinant MetDC was carried out by DEAE-Toyopearl and Ni-NTA agarose column chromatography. The recombinant enzyme was homodimeric with a molecular mass of 61,000 Da and showed optimal activity between 45 to 55 °C and at pH 6.6, and the stability below 30 °C and between pH 4.6 to 7.0. L-Methionine and L-norleucine were good substrates for MetDC. The Michaelis constants for L-methionine and L-norleucine were 30 and 73mM, respectively. The recombinant MetDC (0.50 U/ml) severely inhibited growth of human tumour cells A431 (epidermoid ovarian carcinoma cell line) and MDA-MB-231 (breast cancer cell line), however showed relatively low cytotoxicity for human normal cell NHDF-Neo (dermal fibroblast cell line from neonatal foreskin). This study revealed the properties of the gene and the protein sequence of MetDC for the first time.
Original language | English |
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Pages (from-to) | 389-398 |
Number of pages | 10 |
Journal | Journal of biochemistry |
Volume | 161 |
Issue number | 4 |
DOIs | |
Publication status | Published - Apr 1 2017 |
Keywords
- L-methionine decarboxylase
- antitumour enzyme
- gene cloning
- pyridoxal 50-phosphate
- recombinant expression
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology