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Many of the properties of wasabi myrosinase have been

determined by Ohtsuru and Kawatani (1979). It is one

of the largest myrosinases yet described, having a mole-

cular weight of 580Kd compared to 120-150Kd for

mustard or 90 Kd for Aspergillus niger. It consists of 12

subunits as assessed by sodium dodecyl sulphate-poly-

acrylamide gel electrophoresis (SDS-PAGE). This large

molecular weight may contribute to the poor thermal

stability of this enzyme. Myrosinase is present in the

cells as a particle (insoluble) enzyme which is not readily

extracted by washing with buffer, even with Triton-X,

but requires sonication to release it.

The enzyme has an optimum pH of approximately 7,

at which it is also most stable. It shows maximum

activity at 37℃ over a 20-min period, but rapidly

becomes inactivated at temperatures above 30℃. It is

activated by a number of metal ions including Ca2+,

Co2+, Ni2+, K+, Zn2+ and Mg2+, weakly inhibited by

Fe3+ and strongly inhibited by both Cu2+ and Hg2+. It

is also activated by l-ascorbic acid but not by ascorbic

acid analogs nor by other reducing agents, except in the

presence of ascorbic acid. The optimum concentration

of ascorbic acid was around 2mM (Ohtsuru and

Kawatani, 1979). The fragility of the wasabi myrosinase

means that a wasabi powder containing active enzyme is

difficult to prepare. One solution to this problem is to

blend the wasabi powder with a crude myrosinase pre-

paration, or with powdered mustard, horseradish or

similar myrosinase-containing materials (Ebisawa et al.,

1988). Provided the myrosinase is reasonably pure, the

flavour of the powder should not be a€ected, but any

glucosinolates in the enzyme preparation may impart

additional flavours, such as a mustard, pepper or

horseradish flavour. Work conducted at Lincoln Uni-

versity shows that powdered horseradish may also impart

an unpleasant `turnip' flavour to any final product.

3 Answers

  • 1 decade ago
    Favorite Answer

    WASABI黑芥子酶 許多wasabi黑芥子酶物產是確定Ohtsuru和Kawatani (1979)。 它是一最大的黑芥子酶,描述,有痣cular重量580Kd與120-150Kd比較了為芥末或90黑麴霉的Kd。 包括12個亞單位如鈉十二烷基硫酸鹽多估計它丙烯酰胺膠凝體電泳法(SDS-PAGE)。 大這分子量也許造成恶劣的上升暖流這酵素的穩定。 黑芥子酶是存在細胞作為沒有通过洗滌欣然提取與緩衝,甚而與氚核X的微粒(不能溶解的)酵素,但是要求聲處理發布它。酵素有最宜酸碱度大约7,在哪些它最也是槽櫪。 它顯示最大值在迅速37℃的活動在20分鐘期間,但是变得撤消在30℃之上的溫度。 它是激活由一定數量的金屬離子包括Ca2+, Co2+, Ni2+、,微弱地被禁止的K+、Zn2+和Mg2+ Fe3+和強烈禁止由Cu2+和Hg2+。 它也激活被l抗壞血症的酸,但是不被抗坏血酸類似物亦不被其他脱氧剂,除了在抗坏血酸面前。 最宜的集中抗坏血酸是大约2mM (Ohtsuru和 kawatani 1979)。 wasabi黑芥子酶的脆弱意味着包含活躍酵素的wasabi粉末是难準備。 對這個問題的一種解答將與預備粗暴的黑芥子酶混和wasabi粉末 paration,或者用搽粉的芥末,辣根或相似的黑芥子酶包含的材料(等Ebisawa, 1988)。 假設黑芥子酶是合理地純淨的,粉末的味道不應該是€ ected的,而是其中任一在酶制剂的葡萄糖基芥子油苷也許給予另外調味,例如芥末,胡椒或辣根味道。 工作被舉辦在林肯單 versity表示,搽粉的辣根也許也給予一令人不快的`turnip& #039; 對任何最终产品的味道。

  • Anonymous
    7 years ago



  • 7 years ago



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