英语听力文摘 English Digest 191、变性蛋白

　　The Denatured Egg White
煮鸡蛋还有那么多学问哪?在煮鸡蛋过程，鸡蛋会发生哪些变化呢?
蛋白质变性（protein denaturation）是指蛋白质在某些物理和化学因素作用下其特定的空间构象被改变，从而导致其理化性质的改变和生物活性的丧失，这种现象称为蛋白质变性。
Have you ever wondered how heating an egg white turns that uncooked clear goo into an opaque¹ gel?

　　Well, that transparent² goo is made of mostly water and proteins. Each protein is a long strand³ of amino acids that you can think of as a string of green and red Christmas lights. The green lights are hydrophilic amino acids, which attract water, and the red lights are hydrophobic amino acids, which hate water.
Each protein is coiled up in a big clump⁴ so that most of the water-loving green lights point outwards⁵ from the mass while most of the water-hating red lights point towards the inside to keep dry.
These coiled up proteins float around in small clumps⁶ allowing light to easily pass through the goo and provide little structure, so the goo is clear and liquidy.
Heating the goo causes the coiled up proteins to unwind, or “denature”, exposing the water-hating red lights to water.
To keep dry red lights from neighboring proteins glue together forming small nets of denatured proteins.
Heat continuously applied⁷ to the goo produces a snowball effect as more proteins are denatured and aggregate⁸ together producing many additional small protein nets, which in turn glue together into bigger and bigger nets; giving structure to the goo and blocking light from passing through it.
Eventually via this process the egg white is transformed from a once clear and gooey substance into an opaque gel.

1 opaque   

adj.不透光的；不反光的，不传导的；晦涩的

参考例句：

• The windows are of opaque glass.这些窗户装着不透明玻璃。
• Their intentions remained opaque.他们的意图仍然令人费解。

2 transparent   

adj.明显的，无疑的；透明的

参考例句：

• The water is so transparent that we can see the fishes swimming.水清澈透明，可以看到鱼儿游来游去。
• The window glass is transparent.窗玻璃是透明的。

3 strand   

vt.使（船）搁浅，使（某人）困于（某地）

参考例句：

• She tucked a loose strand of hair behind her ears.她把一缕散发夹到了耳后。
• The climbers had been stranded by a storm.登山者被暴风雨困住了。

4 clump   

n.树丛，草丛；vi.用沉重的脚步行走

参考例句：

• A stream meandered gently through a clump of trees.一条小溪从树丛中蜿蜒穿过。
• It was as if he had hacked with his thick boots at a clump of bluebells.仿佛他用自己的厚靴子无情地践踏了一丛野风信子。

5 outwards   

adj.外面的，公开的，向外的；adv.向外；n.外形

参考例句：

• Does this door open inwards or outwards?这门朝里开还是朝外开？
• In lapping up a fur,they always put the inner side outwards.卷毛皮时，他们总是让内层朝外。

6 clumps   

n.（树、灌木、植物等的）丛、簇( clump的名词复数 )；（土、泥等）团；块；笨重的脚步声v.（树、灌木、植物等的）丛、簇( clump的第三人称单数 )；（土、泥等）团；块；笨重的脚步声

参考例句：

• These plants quickly form dense clumps. 这些植物很快形成了浓密的树丛。 来自《简明英汉词典》
• The bulbs were over. All that remained of them were clumps of brown leaves. 这些鳞茎死了，剩下的只是一丛丛的黃叶子。 来自《简明英汉词典》

7 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

8 aggregate   

adj.总计的，集合的；n.总数；v.合计；集合

参考例句：

• The football team had a low goal aggregate last season.这支足球队上个赛季的进球总数很少。
• The money collected will aggregate a thousand dollars.进帐总额将达一千美元。