Purification and characterization of a phytase (myo-inositol-hexakisphosphate phosphohydrolase) accumulated in maize (Zea mays) seedlings during germination

Abstract

Phytase (myo-inositol-hexakisphosphate phosphohydrolase, EC 3.1.3.8) has been purified from 5-7-day-old maize (Zea mays) seedlings, using a four-step purification procedure. The native protein has a molecular mass of about 76 kDa and is built up from two 38 kDa subunits. The pH and temperature optima of the purified enzyme were respectively 4.8 and 55 degrees C. The apparent Km for phytate was estimated to be 117 microM. Like other acidic phytases, the maize seedling enzyme exhibited a broad affinity for various phosphorylated substrates and especially for penta- and tri-phosphate esters of myo-inositol. The amino acid composition of the h.p.l.c.-purified protein indicated a high hydrophobicity (44% non-polar amino acids). Rabbit antibodies were produced in response to maize seedling phytase. Western-blot analyses clearly demonstrate that the increase of phytase activity observed during the first 7 days of germination corresponded to an accumulation of the protein in maize seedlings. Phytase accumulated essentially in the shoots (mesocotyl plus coleoptiles.

An Arabidopsis Purple Acid Phosphatase with Phytase Activity Increases Foliar Ascorbate

“…Under our assay conditions, the optimum hydrolysis of phytate was recorded at pH 4.5, in accordance with phytase activity data previously reported for soybean and maize (Fig. 5;Laboure et al, 1993;Hegeman and Grabau, 2001). …”

Digestibility and metabolic utilization of diets containing whole-ear corn silage and their effects on growth and slaughter traits of heavy pigs1

“…Phytic P and phytase are not accumulated in the corn ear and cob (Laboure et al, 1993). Phytic P accumulates in the grain during the ripening stage (Maga, 1982); hence, WECS, which is harvested before the grain completely ripens, is characterized by a lower phytic P content than corn grain.…”

Caracterização parcial e utilização da fitase extraída de sementes germinadas de girassol

“…Chang (1967) e Lolas & Markakis (1977) observaram que a fitase de milho e feijões-navy apresentou maior atividade a 50ºC, enquanto Sutardi & Buckle (1985) observaram que a fitase de soja apresentou atividade máxima a 60ºC. Peers (1953), Laboure et al (1993) e Greiner et al (2000) relataram que a fitase de trigo, milho e cevada apresentaram temperatura ótima de atividade a 55°C.…”

“…O material foi centrifugado por dez minutos a 2.000 rpm e o sobrenadante filtrado em papel-filtro. O teor de fitato foi quantificado segundo Latta & Eskin (1980), com modificação da resina para Dowex-AGX-4, conforme descrição de Ellis & Morris (1986). A leitura foi realizada em espectrofotômetro a 500 nm e os resultados foram expressos em gramas de fitato por 100 gramas de farinha de girassol, em base seca.…”