成人无码AV网站在线观看,国产熟女乱子视频正在播放,色老头在线一区二区三区,免费夜色污私人影院在线观看

 概述

Polyphenol oxidase (tyrosinase) is a bifunctional, copper-containing oxidase having catecholase and cresolase activity. It is responsible for browning reactions through the phylogenetic scale. The enzyme has a molecular weight of 128 kDa. It is a tetramer containing four atoms of copper per molecule and two binding sites for aromatic compounds including phenolic substrates. There is a distinct binding site for oxygen. The optimum pH range is 6-7.

• 分子量：約128 KDa 。

• 適宜溫度25℃。

  最佳PH：6.0～7.0。

技術(shù)規(guī)格

來源：Mushrooms (Agaricus bisporus)

性狀：A lyophilized powder.

酶活：≥500 units per mg dry weight

酶活定義：One unit causes an increase in the absorbance at 280 nm of 0.001 per minute at 25°C, pH 6.5, using L-tyrosine as substrate.

儲存條件：-20°C.

用途：生化試劑

 它催化酪氨酸氧化成多巴和多巴進(jìn)一步氧化成能產(chǎn)生黑色素的前體物——多巴醌。

 可催化含酚基化合物(如酪氨酸、酚類化合物等)氧化成醌的酶。此類酶廣泛存在于自然界，植物中分布很廣，如馬鈴薯、茶葉、漆樹乳汁中含量相當(dāng)高。高等動(dòng)物的皮膚、毛發(fā)、角膜中的黑色素也是由于此酶氧化酪氨酸所生成的產(chǎn)物。蘑菇等菌類及其他微生物中也產(chǎn)生此類酶。通常從野蘑菇中提取，系生物催化劑之一，含有銅離子的蛋白質(zhì)。等電點(diǎn)<5.0；含氮量約13.6％。含銅量約0.25％。紫外吸收峰在273nm和330nm處。

其它包裝規(guī)格請按需詢