Sun, 27 Jul 2008 07:57:38 BST CiteULike: dchen's protein http://www.citeulike.org/user/dchen/tag/protein CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2911590 <i>Soft Matter, 2007, 3, 155 - 167, DOI: 10.1039/b611137h</i><br /><br />This review discusses the structure and phase behaviour of mixtures of colloidal particles and non-adsorbing polymers in the protein limit of large polymers and small colloids. The vast majority of work on colloid–polymer mixtures has been concerned with the colloid limit of large colloidal particles and small polymer chains. In this regime, the diameter of the colloidal particles, , is larger than the characteristic size of the polymer—taken as twice their radius of gyration, Rg. The opposite limit, of size ratios , is called the protein limit due to the common practice of adding polymer to protein solutions in order to aid protein crystallisation. Theoretical predictions for systems in the protein limit are considered briefly and then the main focus is on recent experimental studies of mixtures in the protein limit. Colloid–polymer mixtures in the protein limit Kevin Mutch Jeroen van Duijneveldt Julian Eastoe Soft Matter, 2007, 3, 155 - 167, DOI: 10.1039/b611137h 2008-06-20T22:36:36-00:00 Soft Matter, 2007, 3, 155 - 167, DOI: 10.1039/b611137h 2007 colloids polymer protein review http://www.citeulike.org/user/dchen/article/2910646 <i>Soft Matter, 2006, 2, 377 - 385, DOI: 10.1039/b600098n</i><br /><br />We present an overview of the physical properties of spider silks, and introduce a model designed to study the energy absorbed by the material as it stretches before breaking. Of particular interest are the inter- and intramolecular hydrogen bonds as well as the role of water in modifying the material properties of silk. A solid understanding of this interaction is of paramount importance for any deeper insights into the mechanical properties of any biomaterial. Here we note that the typical biological material has evolved to function in the fully hydrated i.e. elastomeric state. We conclude that silk after its transformation from the hydrated feedstock to the dehydrated fibre state can in fact be analysed in great detail and interpreted as representative of a wide range of elastomeric proteins covering, inter alia, bone, keratins, elastin and collagen. Spider silk as archetypal protein elastomer Fritz Vollrath David Porter Soft Matter, 2006, 2, 377 - 385, DOI: 10.1039/b600098n 2008-06-20T14:58:06-00:00 Soft Matter, 2006, 2, 377 - 385, DOI: 10.1039/b600098n 2008 biology polymer protein http://www.citeulike.org/user/dchen/article/2870176 <i>Physical Review Letters, Vol. 100, No. 20. (2008)</i><br /><br />We introduce an equation for protein native topology based on recent analysis of data from the Protein Data Bank and on a generalization of the Landau-Peierls instability criterion for fractals. The equation relates the protein fractal dimension df, the spectral dimension ds, and the number of amino acids N. Deviations from the equation may render a protein unfolded. The fractal nature of proteins is shown to bridge their seemingly conflicting properties of stability and flexibility. Over 500 proteins have been analyzed (df, ds, and N) and found to obey this equation of state. Proteins: Coexistence of Stability and Flexibility Shlomi Reuveni Rony Granek Joseph Klafter doi:10.1103/PhysRevLett.100.208101 Physical Review Letters, Vol. 100, No. 20. (2008) 2008-06-06T18:12:26-00:00 2008 Physical Review Letters 100 20 APS 2008 biology modulus protein shear theory http://www.citeulike.org/user/dchen/article/2759228 <i>Physical Review Letters, Vol. 100, No. 16. (2008)</i><br /><br />With a model that incorporates hydrodynamics directly, we show that flow experiments can be used for detecting some characteristics of the DNA elasticity which manifest themselves clearly at large length scales but cannot be observed by mechanical forcing experiments even at very small length scales. By systematic analysis, the conclusiveness of different experimental methods is evaluated. For the wormlike chain, confirmed as the correct model for DNA, we find an underlying scaling relation between its extension and flow velocity of the form Lp~v0.155, which emphasizes the significance of hydrodynamics. Analysis of DNA Elasticity RP Linna K Kaski doi:10.1103/PhysRevLett.100.168104 Physical Review Letters, Vol. 100, No. 16. (2008) 2008-05-05T21:17:56-00:00 2008 Physical Review Letters 100 16 APS 2008 biology elasticity flow protein http://www.citeulike.org/user/dchen/article/2759188 <i>Physical Review Letters, Vol. 100, No. 16. (2008)</i><br /><br />Fluorescence spectroscopy of single proteins at liquid-helium temperatures reveals a relation between structural dynamics and biological functions of the proteins. The technical difficulties in detecting visible fluorescence are chromatic aberration and optical background. They were overcome by a new optical design using reflective optics and employing two-photon excitation. The fluorescence spectrum of single green-fluorescent proteins taken at a temperature of 1.5 K makes a distinction between different metastable conformations that last for tens of seconds. Visible Fluorescence Spectroscopy of Single Proteins at Liquid-Helium Temperature Satoru Fujiyoshi Masanori Fujiwara Michio Matsushita doi:10.1103/PhysRevLett.100.168101 Physical Review Letters, Vol. 100, No. 16. (2008) 2008-05-05T20:53:11-00:00 2008 Physical Review Letters 100 16 APS 2008 biology microscope protein structure technique