Gabriel439's Quiocho:FA [5 articles]

Abstract

The thermodynamics of the binding of L-arabinose and of D-galactose to the L-arabinose-binding protein of Escherichia coli have been studied by isothermal and scanning calorimetry. The binding reaction with arabinose is characterized by an enthalpy change of -15.3 +/- 0.5 kcal mol-1 at 25 degrees C, and a large decrease in apparent heat capacity, amounting to -0.44 +/- 0.05 kcal K-1 mol-1, which is constant over the temperature range 8 to 30 degrees C. Very similar results were obtained with D-galactose. ...

Abstract

We have determined and refined the X-ray crystal structures of six periplasmic binding proteins that serve as initial receptors for the osmotic-shock sensitive, active transport of L-arabinose, D-galactose/D-glucose, maltose, sulphate, leucine/isoleucine/valine and leucine. The tertiary structures and atomic interactions between proteins and ligands show common features that are important for understanding the function of the binding proteins. All six structures are ellipsoidal, consisting of two similar, globular domains. The ligand-binding site is located deep in the cleft between the two domains. ...

Abstract

High-affinity uptake into bacterial cells is mediated by a large class of periplasmic binding protein-dependent transport systems, members of the ATP-binding cassette superfamily. In the maltose transport system of , the periplasmic maltose-binding protein binds its substrate maltose with high affinity and, in addition, stimulates the ATPase activity of the membrane-associated transporter when maltose is present. Vanadate inhibits maltose transport by trapping ADP in one of the two nucleotide-binding sites of the membrane transporter immediately after ATP hydrolysis, consistent with its ...

Abstract

The L-arabinose-binding protein (ABP) of Escherichia coli consists structurally of two distinct globular domains connected by a hinge of three separate peptide segments. Arabinose is bound and completely sequestered within the deep cleft between the two domains. With reduced affinity, ABP also binds D-galactose (approximately 2-fold reduction) and D-fucose (approximately 40-fold reduction). Experiments have been conducted to explore the role in sugar binding of the hinge connecting the two domains of ABP. To increase the flexibility of the hinge region, a ...