This is fascinating. It seems that a very minor change in one of our photoreceptors could give us near-infrared vision. I'm very intrigued by this. I think colour totally rocks and the more, the merrier. I wanna mutate now.
How to see a redder redWhen Bob Marley sang, “I am redder than red,” he probably did not imagine that chemists would one day capture this imagined hue. But researchers have taken a step in that direction, by tweaking a colour-sensing pigment from the human eye to absorb reds of longer wavelengths than those that we can see.
“We didn’t expect to get redder than red,” says Babak Borhan, a chemist at Michigan State University in East Lansing, who led the study published today in Science.
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A rhodopsin molecule is made of proteins called opsins and a chromophore — the part of the molecule responsible for absorbing different wavelengths of light . Together, the two parts translate light into signals for various colours, which are then interpreted by the brain. In the eye, a chromophore called retinal responds to wavelengths ranging from red, at about 560 nanometres, to blue, at about 420 nm.
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Life in the red
Borhan’s team tinkered with the amino acids in a construct made of retinal and an engineered protein surrogate for opsin, to help reveal which interactions pushed the chromophore furthest in its ability to absorb different wavelengths of light.
And this engineered pigment absorbed far ‘redder’ wavelengths — 644 nm — than a natural red-sensing rhodopsin would 'see'.
“What’s interesting is they didn’t cause the chromophore to twist [change shape] at all — they showed you could get a red shift by neutralizing a positive charge,” Sakmar says. “I think people will now want to engineer new pigments on the basis of this work. To me, that’s the definition of a cool paper — people will use it.”
For Borhan, one tantalizing detail remains elusive: a glimpse into what life looks like with photoreceptors that absorb 644-nm wavelengths of light. “I guess we’d see far into red, but not so red that we’d see heat signatures,” he says. “We’d see reds in greater definition, but really, I can’t know for sure.”
Topic: How to see a redder red