Author Topic: Visual acuity, vitamin A, and visual transduction...  (Read 20 times)

Tsathoggua

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Visual acuity, vitamin A, and visual transduction...
« on: June 03, 2013, 07:54:48 PM »
Long story short, i'm still reading, of course (I almost always am if I am neither away from somewhere it isn't uncomfortably long to carry a backpack of journal prints with me, or sleeping)  but input is appreciated, particular from those with experience in either the field of visual aquisition, or in-silico modelling  as I have no comp-chem experience...

If I had..I might well know I'm barking up the wrong kettle of fish entirely, but hey, I don't, I get a license to ask a couple of n00b questions...

Since visual signal transduction depends on the active conformation of the end retinoid pigments (vitamin A usually providing the dietary precursors, and carotenoids as safer precursors, being seemingly rate-limited)

Retinoid is incorporated into visual pigment, such as rhodopsin, and from what I read, the vitamin A portion is the chromophore, (wrong word, strictly, probably, but hey, I'm tired, I'm sleep deprived, I'm down to a bit of friggin codeine until I get my oxy rx tomorrow... and wired off my tits thanks to some synthetic cannabinoid and 5HT/general monoamine releaser/reuptake inhibitor product obtained locally from the fine local purveyer of such (I hope that isn't going to be called sourcing....but...to narrow it down...its to within whatever range, over the size of a city, one can  walk, walk back swearing and cursing...catch some public crap transport to, and fuck off again, half passed out from the searing...bastard..UK...heat...ICK.....no antiseizure meds...other than booze.....I'm not going to look a better one up right now......whilst carrying half one's own body weight in cast off copper pipe, brass machine shop detritus, Pb rad shielding (not hot, of course), car weights, broken windows, and a several gallon plant pot full of random similar shite, in the boiling heat, wearing several layers of heavy leather trenchcoat....

Oops...

(just try taking two loads of that lot over a city on foot, propped on your back...and see how much you need to really not spent fucking time looking that kind of thing up and how long ;D

Anyhow-idea:

The conformation, as dictated by degrees of freedom to move about, rigidity conferred via double bonds of the retinal chain, of the final visual pigment appears to dictate absorption frequency range....

So....taking in mind that the eye itself blocks out a fair bit of the UV range, mechanically, perhaps narrowband near-UV to IR ranges may be most practical, in terms of theoretical stuff, what can you guys contribute (note....currently not the best time or state for toady to be posting...rolling his arse off while sleep deprived and scatter brained....)

So, anyone think it could be done? would such an altered retinoid successfully form a vitamin A or carotene prodrug that would be taken up by the eye and actually used? Plenty of enzymes have some room for movement in terms of substrates they will accept, but there will be limits, I could easily see the wrong conformation of retinoid being forced away from an active site due to steric reasons...
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