Peroxidase from peach fruit: thermal Stability

Abstract

Peroxidase from peach fruit was purified 28.9-fold by

Ionically Bound Peroxidase from Peach Fruit

“…The optimum temperature was 40°C and 40% of the maximum activity was registered at 55°C indicating a heat labile enzyme. The apparent activation energy (Ea) value for product formation was found to be 10.04 kcal/mol, in contrast the temperature coeficient (Q 10 ) calculated from this Ea value was 1.78 in the range of 20-30°C, a similar value found for other peroxidases (Bruemmer et al, 1976, Joffe & Ball, 1962, Neves & Lourenço, 1998, Lourenço et al, 1995. Figure 4 shows the time course inactivation of purified peach ionically bound POD from 60 to 75°C.…”

“…Enzyme assay: Soluble and ionically bound peroxidase activities were determined by change in absorbance at 460 nm due to o -dianisidine oxidation in the presence of hydrogen peroxide and the enzyme (Neves & Lourenço, 1998). The reaction mixture consisted of 0.2 ml 15 mM Odianisidine; 0.2 ml 10 mM hydrogen peroxide, 0.1 M potassium phosphate-citrate buffer, pH 5.0 in a total volume of 3.0 ml.…”

“…Peroxidase activity has been investigated in a range of fruits including grape , mangoes (Khan & Robinson, 1993-a), papaya (Silva et al, 1990), pears (Moulding et al, 1989), oranges (Clemente, 1996), peaches (Lourenço & Neves, 1997, Neves & Lourenço, 1998 and apples (Moulding et al, 1987). The enzyme occurs in multiple molecular forms and is present in most fruits and vegetables in a soluble and bound (ionically and covalently) forms (Moulding et al, 1987, Silva et al, 1990, Thomaz et al, 1981, Wang & Lu, 1983, whose catalytic properties are influenced by variety or/and cultivar, growth and physiological stages.…”

“…The activity of the ionically bound peroxidase form from papaya was greatly increased with ripening but gradually fell as the fruit turned from ripe to over-ripe stage (Silva et al, 1990). It is generally accepted that peroxidase is the most heat-stable enzyme in vegetables and that under conditions of limited treatment, it can regain its activity during storage of processed foods (Burnette, 1977, Chang et al, 1988, Khan & Robinson, 1993b, Clemente, 1996, Neves & Lourenço, 1998. Polyhydric alcohols and sugars have been utilized as anti-denaturant agents against freeze and heat-induced denaturation in proteins (Arakawa & Timashef, 1982, Lee & Timashef, 1981, Chang et al, 1988 and in the fruit processing most of these compounds could be used.…”

Biochemical characterization of Santalum album (Chandan) leaf peroxidase

“…Similarly highest activities were shown in case of tobacco leaf at 70°C, (Silva et al, 1990), in Ricinus at 60°C (Ryan et al 1994), in lima bean (Phaseolus limensis) seed at 55°C (Wang et al 2008), in sunflower at 50°C (Hager et al 2008) and in peach fruit at 40°C (Neves 2002;Neves and Lourenço 1998) and a ranges of 40-70°C…”