Possible? Vitamin D synthesis using normal light instead of UV

[n_ana]

Hi all,

let me warn you in advance, this is a very speculative question ;-)

For my master course, I am asked to develop a new research proposal in the field of synthetic biology.

The topic I was interested in is the dilemma that Vitamin D synthesis in animal needs high energetic UV radiation which is harmful for DNA and RNA and yields are very sensitive to physiological aspects (melanin pigmentation) and sufficient amount of UV radiation (time exposure,latitude etc.).

So my idea was to create an artificial system, which uses "normal" visible radiation to synthesize Vitamin D:

 

The synthesis of Vitamin D occurs in the our skin tissue, where the molecule 7-dehydrocholesterol is transformed into preVitamin D by using light energy obtained from UV radiation.

The energy amount of a UV photon is high enough to bring electrons from 7HDC into such an excited stage that eventually breaks a binding and let the molecule transform into the preVitaminD structure.

The formation of Vitamin D seems to exclusively work via this UV light photoreaction,where wavelength of 270-300 nm are most effective. It seems that this high energies of UV photons (4,1744 eV) are needed to initiate the electrocyclic reaction in 7DHC.
No VitaminD is formed in animals by exposure to visible "low-energy" light.

 

Plants instead use this low-energy light to build up biomass from anorganic carbon. Inside their sophisticated molecular "photoreactors", pigments of chlorophyll tunnel these photons in order to excite electrons into higher energetic states.
The most efficient absorption happens at wavelength of 665nm/465nm, which correspond with photon energy levels between 1,86 and 2,67 eV . The photon energy needed to break the chemical bond of 7DHC to form preVitaminD3 is about 2-3 times higher than the photon energy used by the photosystems in the chloroplasts.

Q: Could we create an artificial light-harvesting system that uses visible light to break the chemical bond in 7DHC?

 

Q: Can this be accomplished by physical "tunneling" of low energy photons, so that their energy sums up to initiate the reaction in 7DHC?

I was thinking about an engineered membrane system that has several photon-collector molecules through which 7DHC can receive enough photons to transform into preVitaminD. I am not expert in chemistry, so I can't really estimate what is needed to have a specific chemical bond being broken and if you can actually sum up photon energies like that.

Maybe you have any thoughts or ideas on that?

 

[Justin.Frank]

Hello. In my opinion, I don't think the low energy photons can finish the bond breaking, unless you can find a new catalyzst or new enzyme.

 

Could you design a recombinant enzyme using ATP to provide the energy to break the bond? I'm not professional in this field, but hope useful.