Microsoft SecondLight

Microsoft researchers demonstrate SecondLight, a new variation of the company’s Surface technology.

Handedness in Molecules?

Some molecules possess “handedness.”  They call these left and right handed pairs enantiomers, which are mirror images of each other.  There are many examples of handedness.  You may remember thalidomide.  Thalidomide was given in the mid-50s and early 60s as a morning sickness medication.  The form denoted as (S)-thalidomide is teratogenic and causes birth defects, while the other form ((R)-thalidomide) is effective against morning sickness.

My favorite example of enantiomers which everyone can relate to is the chemical which is responsible for the smell of oranges and lemons.  The name of the chemical, limonene, comes from the lemon (obviously) but is present in many citrus fruit rinds.

D-Limonene (Orange) and L-Limonene (Lemon)

By the look of the way that molecular diagram is drawn, there is no difference between the two molecules.  The picture shows the mirror plane but does not illustrate the difference.  This does:

D-Limonene (or (R)-Limonene) (Orange)

L-Limonene (or (S)-Limonene) (Lemon)

The filled in wedge (D-Limonene) compared to the dashed-line wedge (L-Limonene) indicate whether that bond in the chemical comes out of or into the plane (i.e. out of your monitor or into your monitor).

Essentially all of the amino acids, used for proteins, in all organisms are in the L- form.  While virtually all naturally occuring simple sugars, or monosaccharides, are in the D- form.  The wrong form is often toxic if there is not a method to secrete, metabolize or isomerize the molecule.  To isomerize would be switching forms (from L to D or visa versa) and a class of enzymes called isomerases would be an example of a potential role player in the switch.

In 2001 the Nobel Prize in Chemistry was given to three individuals for developing methods for enantiomerically-selective reactions. Before these methods were developed, chemical reactions lead to an equal mixture of both forms of the molecule. Biological reactions are extremely efficient at selecting an enantiomer. Some of the molecules synthesized by these Nobel laureates which interest me are naproxen (Aleve) and L-DOPA. The movie “Awakenings,” with Robin Williams, is a popular movie in which L-DOPA is a major part of the plot. L-DOPA is converted into dopamine in the brain and is used as a treatment for diseases such as Parkinson’s disease.  The following is a link to an article regarding the 2001 Nobel Prize in Chemistry:

2001 Nobel Prize in Chemistry.pdf