Saturday, March 15, 2008

Why we are made of only left-handed amino acids? A molecular concept of Life.

Most biomolecules are "chiral", that is to say they exist in two left and right -handed mirror image forms. But biology only uses one hand, i.e. it is "homochiral". Life on Earth is made of left handed amino acids, almost exlusively. One of the greatest puzzles in biophysics is the question of why life on Earth is based on left-handed (L) amino acids?

Recently Prof. Pedro Chintas (Angew. Chem. Int. Ed. 2008. 47. 2-5.) described that fractional sublimation of enantiomeric excess(ee) compounds may improve substantially a small ee.
This results a useful protocol for resolving racemate, and suggest that the improvement of optical activity attained by such thermal process could be more efficient than or at least an alternative to, spontaneous crystallization of suitable compounds

He conclude that sublimation should be regarded as a reasonable mechanism for the formation of optically active crystals. These optically enriched crystals of enantiopure compounds easily conducted by natural agents might have generated highly enantiopure niches in the prebiotic world.
Molecular evolution might lead to life but it is not scientifically valid because life is a non- physical, non-chemical entity.

Saturday, March 8, 2008

The Histamine H4 Receptor : Drug Discovery in the Post-genomic Era.

The Histamine H4R receptor is the most recently identified G-protein couple receptor, with little homology to the classical pro inflammatory histamine H1 or the histamine H2 receptor, and some 35% homology with H3 receptor.

The high expression of the histamine H4 receptor in cells of hemopoietic lineage and immune cells suggests that this new histamine receptor plays a role in inflammatory and immune responses. Activation of the Histamine receptor can mediate calcium mobilisation and chemotaxis in mast cells.
Preliminary studies on the H4R and specific antagonist (JNJ 7777120 - Johnson & Johnson, VUF6002-Janssen Pharma.) suggests that another rich vein of histamine receptor therapeutics, likely to generate more blockbusters and medical break throughs, could be on the horizon.
Nature Reviews Drug Discover,7, 41-53, 2008, Trends Pharmacol. Sci. 26, 462-469, 2005