A polypeptide of 100 residues will have 99 peptide bonds, and therefore 198 different phi and psi bond angles. If each of these bond angles can be in one of three stable conformations, the protein may misfold into a maximum of 3198 different conformations (including any possible folding redundancy). Therefore if a protein were to attain its correctly folded configuration by sequentially sampling all the possible conformations, it would require a time longer than the age of the universe to arrive at its correct native conformation. This is true even if conformations are sampled at rapid (nanosecond or picosecond) rates.
"Secretome City" - Illustration based on a 2-D DIGE image
Fluorescence 2-D difference gel electrophoresis (2-D DIGE) with two different CyDye fluors can be used for direct differential protein expression analysis. Here, the cellular proteome was compared to the “secretome”, both derived from the same colon cancer cells in vitro. Green spots represent proteins exlusively present in the cell lysate and red spots show proteins highly enriched in the secretome. The image was produced by Martin W. Volmer, a PhD student in the group of Irmgard Schwarte-Waldhoff at the University of Bochum, Germany, and illustrates part of a project investigating the role of the tumor suppressor gene Smad4 in colorectal carcinogenesis and its impact on the tumor cells’ microenvironment. Further information can be found in Volmer et al (2004), Proteomics, in press.
The original image is printed with kind permission of Proteomics (Wiley-VCH).
A Lanzarote (Isole Canarie) per proteggere le piantine di vite dall’incessante vento, queste vengono allevate senza sostegno e attorno ad ogni piantina è costruito un muretto. In alcuni casi nelle zone più aride e ventose la vite viene piantata in buche a imbuto per raccogliere anche le piccole rugiade e preservare la vite dalla siccità dovuta all’eccessiva traspirazione.
Oggi ho visto una sciarpa di Gucci e la prima cosa che ho pensato appena notato il marchio con le due G è stata: “ma la guanina si appaia con la citosina non con un’altra guanina”
Cose normali insomma. :)