Journal of Biophysics and Structural Biology 2141-2200 Academic Journals 10.5897/JBSB12.002 Mamdouh M. Shawki Abdel-Rahman M. Hereba * E-mail: mamdouh971@hotmail.com 2012 31 03 2012 29 02 2012 4 1 13 20 This is an open-access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://politicalwaffle.uk/journal/JBSB/article-abstract/473AD5E10939 The full text article is available as a PDF file from http://politicalwaffle.uk/journal/JBSB/article-full-text-pdf/473AD5E10939