Utilization of sterol carrier protein-2 by phytanoyl-CoA 2-hydroxylase in the peroxisomal alpha oxidation of phytanic acid.

Since it possesses a 3-methyl group, phytanic acid is degraded by a peroxisomal alpha-oxidation pathway, the first step of which is catalyzed by phytanoyl-CoA 2-hydroxylase (PAHX). Mutations in human PAHX cause phytanic acid accumulations leading to Adult Refsum's Disease (ARD), which is also observed in a sterol carrier protein 2 (SCP-2)-deficient mouse model. Phytanoyl-CoA is efficiently 2-hydroxylated by PAHX in vitro in the presence of mature SCP-2.

Structure-function analysis of phytanoyl-CoA 2-hydroxylase mutations causing Refsum's disease.

Refsum's disease is a neurological syndrome characterized by adult-onset retinitis pigmentosa, anosmia, sensory neuropathy and phytanic acidaemia. Many cases are caused by mutations in peroxisomal oxygenase phytanoyl-CoA 2-hydroxylase (PAHX) which catalyses the initial alpha-oxidation step in the degradation of phytanic acid. Both pro and mature forms of recombinant PAHX were produced in Escherichia coli, highly purified, and shown to have a requirement for iron(II) as a co-factor and 2-oxoglutarate as a co-substrate.

Structural and thermodynamic characterization of the interaction of the SH3 domain from Fyn with the proline-rich binding site on the p85 subunit of PI3-kinase.

The interaction of the Fyn SH3 domain with the p85 subunit of PI3-kinase is investigated using structural detail and thermodynamic data. The solution structure complex of the SH3 domain with a proline-rich peptide mimic of the binding site on the p85 subunit is described. This indicates that the peptide binds as a poly(L-proline) type II helix.

Water-mediated protein-DNA interactions: the relationship of thermodynamics to structural detail.

The elucidation of a relationship between the thermodynamic parameters and the structural changes accompanying biomolecular interactions could lead to predictive algorithms. For example, based on some knowledge of the structure of a target molecule the affinities of ligands could be determined with obvious implications for the pharmaceutical industry. In attempting to relate the thermodynamic and structural changes on formation of a protein-DNA complex, the correlation between change in heat capacity and burial of surface area has proved successful.

Structural studies of synthetic peptides dissected from the voltage-gated sodium channel.

Peptides representing transmembrane regions of the alpha-subunit of the voltage-gated sodium channel were synthesised and their structures analysed, using 1H NMR and CD, in trifluoroethanol and in dodecylphosphocholine micelles. Sequence analysis suggests that the channel has six regions, S1 to S6, predicted to span the membrane in four homologous domains, designated, I, II, III and IV. Presented here are studies of representatives examples of possible single spanning segments (IS2, IS4, IVS4) and a double spanning segment, IS34, composed of segments IS3 and IS4.

Molecular modeling of the GM-CSF and IL-3 receptor complexes.

A model for the structure of the cytokine interleukin-3 (IL-3) is presented based on the structural homology of the hematopoietic cytokines and utilizing the crystal structures of interleukin-5 and granulocyte macrophage colony stimulating factor (GM-CSF). In addition, models of the receptor complexes of GM-CSF and IL-3 are presented based on the structural homology of the hematopoietic receptors to growth hormone. Several key interactions between the ligands and their receptors are discovered, some in agreement with previous mutagenesis studies and others that have not yet been the subject of mutagenesis studies.

The interleukin-2 and interleukin-4 receptors studied by molecular modelling.

Background: Interleukin-2 (IL2) and interleukin-4 (IL4) are members of the four-helix bundle family of cytokines, whose receptors show similarity to each other and to the growth hormone receptor fold. These proteins help to control, among other things, the rate of clonal expansion of lymphocytes, and thus play an important role in the regulation of the immune system. They are therefore of interest as transmembrane signalling proteins, as well as potential pharmaceutical targets.

Predictive modelling of the 3-D structure of interleukin-13.

Several atomic structures are now available for the family of helical cytokines, which includes growth hormone as well as many of the interleukins. Using structural information from five members of this family, two alternative models of interleukin (IL)-13 are proposed. IL-13 has biological properties similar to those of IL-4 and, like the other interleukins, is a potentially important pharmaceutical target.

A computer model of the interleukin-4/receptor complex.

Interleukin-4 is a member of the cytokine family, a group of related messenger proteins which collectively help to moderate and control the immune response. It is believed that the folding topology of the beta-sheets of the interleukin-4 receptor (IL4R) is the same as that seen in the crystal structure of CD4. Although the sequence identity is low, homology modeling techniques have been used to model the IL4R structure from CD4.

Histamine tautomerism and its mode of action.

An established combination of quantum mechanical calculations and molecular dynamics simulations (Worth, C.A., King, P.