Lobster colour change mystery solved

 Lobster colour change mystery solved

龙虾变色之谜已解开

For the first time scientists have come up with a precise explanation for why lobsters change colour from blue/black to red when cooked.

And the findings could have uses in the food industry and even in the delivery of some anti-cancer drugs.

When alive and living in the sea, lobsters are naturally a dark-blue/black colour. It is thought that natural selection led to this as it makes them harder to spot for predators. But put them in a pan of boiling water and they soon turn the familiar orange-red that is the colour that most people think for lobsters, ie on their dinner plates.

Now scientists from the School of Chemistry at The University of Manchester with their international collaborators have come up with a precise explanation for why, after years of academic discussion. In a paper published in one of the journals of the Royal Society of Chemistry the team describe their findings.

The key is a chemical called astaxanthin, which has the orange-red colour of a cooked lobster, and how it interacts with a complex of proteins called crustacyanin which lobsters produce. The reaction of astaxanthin with the protein complex gives the creature its dark blue colour. But crucially, when the lobster is cooked the protein is denatured and the astaxanthin is released and reverts to its orange-red state. This much was known from the X-ray crystal structure published by members of the same team in 2002.

The remaining scientific issue was the mechanism underlying the colour shift of free to bound astaxanthin. This is a much more complicated question! The clue is that astaxanthin can behave as an acid, a property that has emerged as important when it reacts with the lobster’s crustacyanin proteins. It is this that the new publication has discovered to create the blue colour.

Professor John Helliwell of The University of Manchester, who led the team which carried out the research, said: “Over the last thirteen years since our X-ray crystal structure there have been competing groups studying this coloration mechanism, but hopefully now the issue is solved. It is a scientific curiosity, but it may also have important applications in the real world.”

“The coloration is quite a complex process to do with the 3 dimensional structure of the proteins in complex with the astaxanthins it binds, and the implications could be very useful.”

“For example astaxanthin is an antioxidant, so it has many health properties. But because it is insoluble in water the problem is how to deliver it to a target. But our findings suggest that mixing it with crustacyanin could do that and allow the astaxanthin to get to a target such as via the stomach.”

“It could also be used as food dye, for example to help create blue coloured ice cream. Or it could be used in food stuffs to help people know when food has been cooked properly; a dot on the food that changes colour when it reaches a certain temperature could be used.”

“Most fundamental of all is arousing the curiosity of children and the public in basic science and our marine environment. In the era of climate change it is important for all to think about the delicate nature of life and the sustainability of life on the planet. How and why has lobster evolved this elaborate and delicate coloration mechanism? It is a beautiful and yet intriguing phenomenon.”

龙虾变色之谜已解开

 科学家首次对龙虾煮熟后颜色从蓝色/黑色变为红色的原因提出了精确的解释。

 这些发现可能适用于食品工业，甚至可用于某些抗癌药物的输送。

 当龙虾活着并生活在海中时，龙虾的颜色自然是深蓝色/黑色。 人们认为自然选择导致了这种情况，因为这使得它们更难被掠食者发现。 但是，将它们放入一锅沸水中，它们很快就会变成熟悉的橙红色，这是大多数人认为龙虾的颜色，即餐盘上的颜色。

 现在，经过多年的学术讨论，曼彻斯特大学化学学院的科学家和他们的国际合作者已经给出了一个精确的解释。 在英国皇家化学学会一本期刊上发表的一篇论文中，该团队描述了他们的发现。

 关键是一种叫做虾青素的化学物质，它具有熟龙虾的橙红色，以及它如何与龙虾产生的一种叫做甲壳青素的蛋白质复合物相互作用。 虾青素与蛋白质复合物的反应使该生物呈现深蓝色。 但至关重要的是，当龙虾煮熟时，蛋白质会变性，虾青素会释放出来并恢复到橙红色状态。 从该团队成员 2002 年发表的 X 射线晶体结构中可以了解到这一点。

 剩下的科学问题是游离虾青素向结合虾青素颜色转变的机制。 这是一个更复杂的问题！ 线索是虾青素可以起到酸的作用，当它与龙虾的甲壳青蛋白发生反应时，这种特性变得非常重要。 新出版物发现，正是这种物质创造了蓝色。

 领导该研究团队的曼彻斯特大学教授约翰·海利威尔 (John Helliwell) 表示：“自从 X 射线晶体结构出现以来，过去 13 年里一直有不同的研究小组在研究这种着色机制，但希望现在的问题是 解决了。 这是一种科学好奇心，但它在现实世界中也可能有重要的应用。”

 “着色是一个相当复杂的过程，涉及到与其结合的虾青素复合的蛋白质的 3 维结构，其含义可能非常有用。”

 “例如虾青素是一种抗氧化剂，因此它具有许多健康特性。 但由于它不溶于水，问题是如何将其输送到目标。 但我们的研究结果表明，将其与甲壳青素混合可以做到这一点，并使虾青素能够到达目标，例如通过胃。”

 “它也可以用作食品染料，例如帮助制作蓝色冰淇淋。 或者它可以用在食品中，帮助人们知道食物何时煮熟； 可以使用食物上的一个点，当达到一定温度时会变色。”

 “最根本的是激发儿童和公众对基础科学和海洋环境的好奇心。 在气候变化时代，所有人都必须思考地球上生命的微妙本质和生命的可持续性。 龙虾是如何以及为何进化出这种复杂而微妙的着色机制的？ 这是一个美丽而又有趣的现象。”