The residue-specific contributions to folding in most of the 15 protein molecules are highly non-uniformly

distributed and are typically about 1 piconewton (pN) per interaction. The strongest folding forces often occur in some of the helices and strands of folding nuclei which suggests that folding nucleation-condensation is partially directed by formation of some secondary structure interactions. The correlation of the energy changes of mutants with inter-residue contact maps of the protein molecules provides a higher resolution than assigning the mutant data to certain positions in the polypeptide strand alone. In contrast to previous Phi-value analysis, we now can partially resolve folding motions. Compaction of at least one alpha-helix along its axis mediated HKI-272 purchase by internal hydrogen bonds and stabilized by diffuse

tertiary structure interactions appears to be one important molecular event during early folding in barstar, C12, spectrin R16 domain, Arc ATM inhibitor repressor, alpha-lactalbumin, IM7, IM9, and spectrin R17 domain. A lateral movement of at least two strands neighbored in sequence towards each other appears to be involved in early folding of the SH3 domain, cspB, CTL9, and FKBP12. (C) 2007 Elsevier Ltd. All rights reserved.”
“Iron is required by many microorganisms for growth. Although it is the most abundant transition metal on earth, its solubility is very low and therefore its bioavailability is poor. To overcome this selleck chemicals limitation, many microorganisms have developed iron chelating mechanisms that enable them to bind the metal to organic molecules from which they are later released. In particular, pseudomonads are prominent producers of the chelator pyoverdine

that has a high iron binding capability. We present a mathematical model for pyoverdine production by Pseudomonas fluorescens. It is a nonlinear and non-autonomous system of four ordinary differential equations for the dependent variables size of bacterial population, pyoverdine, dissolved iron and chelated iron. The transient adaptation of the average physiological state of the population to the environmental condition is explicitly included in the model formulation. A complete qualitative description of the model solution is given, based on analytical techniques. The model is quantitatively validated against experimental data of pyoverdine and population size. To this end we conduct and discuss a parameter identification study. It is found that the model, if calibrated using pyoverdine data alone is able to predict the population size and vice versa, with some restrictions. Thus the model can be used as an indirect experimental tool. (C) 2007 Elsevier Ltd. All rights reserved.