4 replies to this topic

[afRNA]

Hi!!!
I,m doing a research in a protein extraction!! I just going to expose UV light to medium for the sterilization purposes.Will it work? and Is protein degrade by UV?

[hobglobin]

Surely depends on protein type, duration, intensity and wavelength, i.e. easily damageable proteins, long durations and lower wavelengths increase the risk. And proteins absorb UV between 280 and 200 nm (e.g. protein concentration assays).
Not sure about the UV absorption of water itself, but I guess in laboratory scale (a few cm) it's negligible.
and forgot to mention that UV is used to disinfecting water...i.e. bacteria, protozoans and viruses are killed/deactivated by protein degradation. Not sure if it's good as autoclaving, i.e. if also spores are killed.
Perhaps you should sterilise your medium before proteins are added.

Edited by hobglobin, 31 August 2012 - 08:13 AM.

[ascacioc]

I do not think UV damages proteins, otherwise CD (circular dichroism) measurements wouldn't work. In CD you expose the protein sample to 190 nm to 320 nm for quite long (a spectrum is 30 min; but a melting curve is a few hours). Moreover, the wavelengths that would produce heating by bond vibrations are higher than UV: more towards IR and microwaves.

Definitely, UV would help in sterilizing. We all use UV to sterilize hoods overnight (UV destroys the DNA by making T dimers).

[hobglobin]

As I wrote it depends on the protein type and intensity (W/m²). In such measurements you don't use the power of a fluorescent lamp...
Anyway for disinfecting it's surely also DNA damage, but as it seems to work also in organisms that shield their DNA with pigmentations or form spores or cysts, so my idea was protein damage (perhaps indirectly via oxidative stress?)

[afRNA]

Thank you for the replay!!!
I've read some article, they use UV for sterilization of milk, but we know milk have various types of proteins. so my question is , Is there range of UV for tolerating certain protein but it kills microbes (specially bacteria)??