In Science Daily of yesterday  I note a paper  “Atomic-resolution Views Suggest Function Of Enzyme That Regulates Light-detecting Signals In Eye” authored  a team of University of Washington and Rutgers investigators.

Quoting from the release:

“The enzyme, phosphodiesterase 6 (PDE6), is central to the way light entering the retina is converted into a cascade of signals to the brain”

I would propose that this enzyme may be “central” in the vision process but not in the biochemical sense that the authors believe.(see below).

A further quote from the release:

“This particular form of the enzyme comes from the cone photoreceptors of the retina and has not been well-researched, in contrast to its rod form. Rods are involved in night vision and motion sensation; the cones are responsible for color sensitivity, visual acuity, daylight vision, and adjustment to bright light.”.

It simply amazes me that this belief is still held and that it forms the basis for thrust of research!

For the record – it is the interreceptor spacing of rods ( importantly exactly forming the short wavelength limit of vision) and the totality of rod area of the peripheral retina acting in concert (there has long been experimental evidence of this) that controls  pupillary constriction and thus entrance of light into the eye. Thus rods, in a sense, do control low light level (or night) vision but not in the way usually and erroneously thought!

It is my contention that the role of protein must be viewed in a structural physics sense controlling the spatial dimensionality of receptors – at the inner segment. It is the inner segment diameter, and the proteins that code for and form this structure, that sets the wavelength determining separation of the light interactive outer segments.

There are obviously other enzymes and uses for same, but the role of the inner and outer segments of receptors can be defined as follows:

THE INNER SEGMENT: In addition to providing the structural spatial separation of outer segments, forms the “factory” for constantly producing thylakoid disks for use in the outer segments.

THE OUTER SEGMENT: A physics based region where the fundamental light interaction process occurs. This is via a classical wave / quantum particle mechanism that I have proposed. The retina can be considered in essence as a logically spaced, wavelength- determinative array of generic quantum confined electron centers. The isomerization of the retinal molecule is the femtosecond time domain, electronic signal producing, center of all receptors both cone and rod.  It is the role of the rhodopsin protein to form the spatially-determinative structure to constrain the retinal molecule to quantum confinement dimension.

Back to the paper, the authors attempt to relate this particular enzyme to the extreme (quantum event sensitive) of the eye is not persuasive – or evenin evidence!

There is certainly a role for biochemistry downstream in an understanding  of the fate of the electronic signal from the outer segment but this region seems a concern of physics.

And I would add that “color” and “pigments” have been taken out of the picture in my explanation!

GCH

10.08.08

This entry was posted on Wednesday, October 8th, 2008 at 8:33 am and is filed under Running Commentary . You can follow any responses to this entry through the RSS 2.0 feed. You can leave a comment, or trackback from your own site.