DISTRIBUTION OF ASCORBATE OXIDASE ACTIVITIES IN THE FRUITS OF FAMILY CUCURBITACEAE AND SOME OF THEIR PROPERTIES

✍ Scribed by NAZAMID BIN SAARI; SHUJI FUJITA; RYUICHI MIYAZOE; MASAHIKO OKUGAWA

• Book ID: 111337038
• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 362 KB
• Volume: 19
• Category: Article
• ISSN: 0145-8884
• DOI: 10.1111/j.1745-4514.1995.tb00537.x

✦ Synopsis

Activities and some other properties of ascorbate oxidases (AA 0) from the @its of family Cucurbitaceae were investigated. l'he peel and the flesh of seven varieties had activities ranging between 35-563W units/mg protein and 14-1250 unitdmg protein, respectively. AAO from different varieties had a similar pH optimum of around 6 6 . 5 and a broad pH stability ranging from pH 5 or 6 to pH 10 or 11. l'hese properties appear to be conserved in the M O S from the family of Cucurbitaceae. 'lhe AAOs of melon cv. andes, kinsho and papaya were more susceptible to heat denaturation than AAO from pumpkin.

INTRODUCTlON

Ascorbate oxidase (AAO, EC 1.10.3.3) is a copper-containing enzyme which catalyzes the oxidation of ascorbic acid (AsA) in the presence of molecular oxygen. There has been much interest in this enzyme among food scientists especially with respect to determination of AsA in food samples. In this regard, several enzymatic methods using the enzyme have been developed (Marchesini et al. 1970(Marchesini et al. , 1972;;Matsumoto et al. 1981; Esaka et at. 1985). However, the use of such methods is still regarded as expensive because of high costs of commercial AAO.