symmetry versus asymmetry in the molecules of life homomeric protein assemblies对称与不对称的分子生命homomeric蛋白质组装.pdf

Symmetry 2010, 2, 884-906: doi:10.3390/sym2020884 OPEN ACCESS symmetry ISSN 2073-8994 /journal/symmetry Article Symmetry versus Asymmetry in the Molecules of Life: Homomeric Protein Assemblies Biserka Kojić-Prodić * and Zoran Štefanić Rudjer Bošković Institute, P.O. Box 180, HR-10002-Zagreb, Croatia; E-Mail: zoran.stefanic@irb.hr * Author to whom correspondence should be addressed; E-Mail: kojic@irb.hr. Received: 27 February 2010; in revised form: 7 April 2010 / Accepted: 12 April 2010 / Published: 19 April 2010 Abstract: The essay is dedicated to the relation of symmetry and asymmetry-chirality in Nature. The Introduction defines symmetry and its impact on basic definitions in science and human activities. The following section Chirality of molecules reveals breifly development of notion of chirality and its significance in living organisms and science. Homochirality is a characteristic hallmark of life and its significance is presented in the section Homochirality of Life . Proteins, important constituents of living cells performing versatile functions are chiral macromolecules composed of L-amino acids. In particular, the protein assemblies are of a great importance in functions of a cell. Therefore, they have attracted researches to examine them from different points of view. Among proteins of known three-dimensional structures about 50–80% of them exist as homomeric