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Journal Issue - Volume 6 Issue 5 (May 1997)

Abstract Interleukin‐6 (IL‐6) is a multifunctional cytokine that plays a central role in host defense due to its wide range of immune and hematopoietic activities and its potent ability to induce the acute phase response. Overexpression of IL‐6 has been implicated in the pathology of a number of diseases including multiple myeloma, rheumatoid arthritis, Castleman's disease, psoriasis, and post‐menopausal osteoporosis. Hence,...

Abstract We have developed an automatic approach for homology modeling using restrained molecular dynamics and simulated annealing procedures, together with conformational search algorithms available in the molecular mechanics program CONGEN (Bruccoleri RE, Karplus M, 1987, Biopolymers 26:137–168). The accuracy of the method is validated by “predicting” structures of two homeodomain proteins with known three‐dimensional structures,...

Abstract The structures of three complexes of human fructose‐1,6‐bisphosphatase (FB) with the allosteric inhibitor AMP and two AMP analogues have been determined and all fully refined. The data used for structure determination were collected at cryogenic temperature (110 K), and with the use of synchrotron radiation. The structures reveal a common mode of binding for AMP and formycine monophosphate (FMP)....

Abstract Fast synaptic neurotransmission is mediated by ligand‐gated ion‐channel (LGIC) receptors, which include receptors for acetylcholine, serotonin, GABA, glycine, and glutamate. LGICs are pentamers with extracellular ligand‐binding domains and form integral membrane ion channels that are selective for cations (acetylcholine and serotonin 5HT3 receptors) or anions (GABAA and glycine receptors and the invertebrate glutamate‐binding chloride...

Abstract A conserved proline‐rich motif (PRM) in the cytoplasmic domain of cytokine receptors has been suggested to be a signaling switch regulated by the action of the FK506 binding protein (FKBP) family of peptidylprolyl isomerases (O'Neal KD, Yu‐Lee LY, Shearer WT, 1995, Ann NY Acad Sci 766:282–284). We have docked the prolactin receptor PRM (Ile1‐Phe2‐Pro3‐Pro4‐Val5‐Pro6‐Gly7‐Pro8) to the ligand binding site of FKBP12. The procedure...

Abstract A key step in plant photorespiration, the oxidation of glycolate to glyoxylate, is carried out by the peroxisomal flavoprotein glycolate oxidase (EC 1.1.3.15). The three‐dimensional structure of this α/β barrel protein has been refined to 2 Å resolution (Lindqvist Y. 1989. J Mol Biol 209:151‐166). FMN dependent glycolate oxidase is a member of the family of α‐hydroxy acid oxidases. Here we describe the crystallization and...

Abstract A bond between the Nδ of the imidazole ring of His 392 and the Cβ of the essential Tyr 415 has been found in the refined crystal structure at 1.9 Å resolution of catalase HPII of Escherichia coli. This novel type of covalent linkage is clearly defined in the electron density map of HPII and is confirmed by matrix‐assisted laser desorption/ionization mass spectrometry analysis of tryptic digest mixtures. The geometry of the bond is compatible ...

Abstract The formulation of HIV‐1 PR inhibitors as anti‐viral drugs has been hindered by the appearance of protease strains that present drug resistance to these compounds. The mechanism by which the HIV‐1 PR mutants lower their affinity for the inhibitor is not yet fully understood. We have applied a modified Poisson‐Boltzmann method to the evaluation of the molecular interactions that contribute to the lowering of the inhibitor...

Abstract For murine adenosine deaminase, we have determined that a single zinc or cobalt cofactor bound in a high affinity site is required for catalytic function while metal ions bound at an additional site(s) inhibit the enzyme. A catalytically inactive apoenzyme of murine adenosine deaminase was produced by dialysis in the presence of specific zinc chelators in an acidic buffer. This represents the first production of the...

Abstract The cytoplasmic regions of the mouse low‐affinity FcγRII isoforms, mFcγRIIb1, and mFcγRIIb2, play a key role in signal transduction by mediating different cellular functions. mFcγRIIb1 has a 94‐residue cytoplasmic region, whereas mFcγRIIb2 has a 47‐residue cytoplasmic region. Genes encoding the cytoplasmic regions of mFcγRIIb1 (b1‐94) and mFcγRIIb2 (b2‐47) were designed, synthesized, and expressed as fusion proteins in...

Abstract The hscA and hscB genes of Escherichia coli encode novel chaperone and co‐chaperone proteins, designated Hsc66 and Hsc20, respectively. We have overproduced and purified Hsc66 and Hsc20 in high yield in E. coli and describe their initial characterization including absorbance, fluorescence, and circular dichroism spectra. Immunoblot analyses of E. coli cultures using antisera to Hsc66 and Hsc20 raised in rabbits establish that Hsc66 and...

Abstract We report a new free energy decomposition that includes structure‐derived atomic contact energies for the desolvation component, and show that it applies equally well to the analysis of single‐domain protein folding and to the binding of flexible peptides to proteins. Specifically, we selected the 17 single‐domain proteins for which the three‐dimensional structures and thermodynamic unfolding free energies are available. By...

Abstract A molten globule‐like state of hen egg‐white lysozyme has been characterized in 25% aqueous hexafluoroacetone hydrate (HFA) by CD, fluorescence, NMR, and H/D exchange experiments. The far UV CD spectra of lysozyme in 25% HFA supports retention of native‐like secondary structure while the loss of near UV CD bands are indicative of the overall collapse of the tertiary structure. The intermediate state in 25% HFA exhibits an...

Abstract The free cysteine residues in the extremely thermophilic Thermoanaerobacter brockii alcohol dehydrogenase (TBADH) were characterized using selective chemical modification with the stable nitroxyl biradical bis(1‐oxy‐2,2,5,5‐tetramethyl‐3‐imidazoline‐4‐yl)disulfide, via a thiol‐disulfide exchange reaction and with 2[14C]iodoacetic acid, via S‐alkylation. The respective reactions were monitored by electron paramagnetic resonance (EPR) and ...

Abstract The crystal structure of the maltodextrin‐specific porin from Salmonella typhimurium ligated with a maltotrioside at the pore eyelet is known at 2.4 Å resolution. The three glucose units assume a conformation close to the natural amylose helix. The pore eyelet fits exactly the cross‐section of a maltooligosaccharide chain and thus functions as a constraining orifice. The oligomer permeates the membrane by screwing along the amylose...

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