Modulation of alkaline phosphatase activity from Saccharomyces Cerevisiae grown in low or high phosphate medium

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Fernandes J (Author) Other; Amorim R (Author) Other; Azevedo I (Author) FMUP; Martins MJ (Author) FMUP

Journal

Title: Brazilian Journal of Medical and Biological Research

Vol. 41 No. 1

Pages: 41-46

ISSN: 0100-879X

Publisher: Associacao Brasileira de Divulgacao Cientifica

Indexing

ISI Web of Science

Scopus

Pubmed / Medline

Scientific classification

CORDIS: Health sciences

Other information

Abstract (EN): Our objective was to characterize the modulation of the activity of Saccharomyces cerevisiae alkaline phosphatases (ALPs) by classic inhibitors of ALP activity, cholesterol and steroid hormones, in order to identify catalytic similarities between yeast and mammalian ALPs. S. cerevisiae expresses two ALPs, coded for by the PHO8 and PHO13 genes. The product of the PHO8 gene is repressible by Pi in the medium. ALP activity from yeast (grown in low or high phosphate medium) homogenates was determined with p-nitrophenylphosphate as substrate, pH 10.4 (lPiALP or hPiALP, respectively). Activation of hPiALP was observed with 5 mM L-amino acids (L-homoarginine - 186%, L-leucine - 155% and L-phenylalanine - 168%) and with 1 mM levamisole (122%; percentage values, in comparison to control, of recovered activity). EDTA (5 mM) and vanadate (1 mM) distinctly inhibited hPiALP (2 and 20%, respectively). L-homoarginine (5 mM) had a lower activating effect on lPiALP (166%) and was the strongest hPiALP activator. Corticosterone (5 mM) inhibited hPiALP to 90%, but no effect was observed in low phosphate medium. Cholesterol, beta-estradiol and progesterone also had different effects on lPiALP and hPiALP. A concentration-dependent activation of lPiALP minus hPiALP was evident with all three compounds, most especially with beta-estradiol and cholesterol. These results do not allow us to identify similarities of the behavior of S. cerevisiae ALPs and any of the mammalian ALPs but allow us to raise the hypothesis of differential regulation of S. cerevisiae ALPs by L-homoarginine, beta-estradiol and cholesterol and of using these compounds to discriminate between S. cerevisiae lPiALP and hPiALP.

Language: Portuguese

Type (Professor's evaluation): Scientific