Nonchemical Approach for Reducing Antinutritional Factors in Rapeseed (Brassica campestrisVar. Toria) and Characterization of Enzyme Phytase

Abstract

Antinutritional factors, viz. glucosinolates, phenols, and phytic acid, decreased with germination of rapeseed. Protein content declined during the first 24 h after imbibition and thereafter increased. Phytase activity increased with germination with a parallel decrease in phytic acid content. Two phytase fractions were separated during elution on DEAE-cellulose column, showing purifications of 26.75- and 19.96-fold, respectively. Optimum pH and temperature for both fractions were 5.2 and 50 °C, respectively. Enzyme stability decreased considerably after 50 °C, and phytase 2 was stable for a longer time. Mn, Co, Ca, and EDTA promoted the enzyme activity, whereas ions of Zn, Fe, Cu, fluoride, molybdate, and arsenate were inhibitory. Keywords: Antinutritional factors; characterization; germination; phytase

The rational design of semisynthetic peroxidases

“…As shown in Fig. 2, both vanadate and molybdate are strong inhibitors, as reported for phosphatases and related enzymes (Lindqvist et al, 1994;Mahajan and Dua, 1997;Stankiewicz and Gresser, 1988;Vescina et al, 1996), whereas tungstate has little influence on the hydrolysis reaction and selenate is not an inhibitor. Inhibition constants (K i ) were calculated at 3.9 and 9.4 M, respectively, for vanadate and molybdate.…”

“…Recently, it was established (Hemrika et al, 1997;Neuwald, 1997) that vanadium chloroperoxidases are structurally closely related to the (membranebound) acid phosphatases, and the apoenzyme of vanadium chloroperoxidase was shown to exhibit phosphatase-like activity. Moreover, vanadate and other transition metal oxoanions are known to be potent inhibitors of acid phosphatases (Lindqvist et al, 1994;Vescina et al, 1996) and the related phytases (Greiner et al, 1997;Mahajan and Dua, 1997) and sulfatases (Stankiewicz and Gresser, 1988). Hence, we reasoned that incorporation of vanadate ion into the active site of these enzymes should produce novel, semisynthetic peroxidases.…”

Phytate in pig and poultry nutrition

“…It is suggested that Ca may inhibit phytase activity (Applegate et al, 2003), while some studies have shown that the Ca-to P-ratio (Ca/P) of the diet affects the response to phytase application (Qian et al, 1996a;Liu et al, 2000). However, there is little tangible evidence that Ca directly inhibits exogenous phytase activity, but data on this aspect are conflicting (Mahajan and Dua, 1997). Nevertheless, to improve phytase activity, it is generally recommended to keep Ca levels to a minimum in phytase-supplemented pig and poultry diets, yet without compromising skeletal integrity or growth performance (Selle et al, 2009).…”

Consequences of calcium interactions with phytate and phytase for poultry and pigs

“…Citing Greiner et al (1993), they attributed this to the inhibition of phytase activity by inorganic P, the end-product of phytate hydrolysis. In an in vitro system, Mahajan and Dua (1997) reported that inorganic P (Na 2 HPO 4 ) inhibited rapeseed phytase activity by up to 80.2%. While there is the possibility that inorganic P may inhibit phytase activity presumably, in vivo, this capacity would be diminished by the absorption of phytaseliberated P from the gastrointestinal tract in vivo.…”