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Journal Issue - Volume 8 Issue 1 (1999)

  • Succeeding a Legend

  • Mark Hermodson
  • Published in Wiley Interscience on Dec 31, 2008
  • DOI: 10.1110/ps.8.1.1 (p 1-4)

Abstract The transmembrane glycoprotein gp130 is the common signal transducing receptor subunit of the interleukin‐6‐type cytokines. It is a member of the cytokine‐receptor superfamily predicted to consist of six domains in its extracellular part. The second and third domain constitute the cytokine‐binding module defined by a set of four conserved cysteines and a WSXWS motif, respectively. The three‐dimensional structure of the...

Abstract The complete amino acid sequence of the lectin KM+ from Artocarpus integrifolia (jackfruit), which contains 149 residues/mol, is reported and compared to those of other members of the Moraceae family, particularly that of jacalin, also from jackfruit, with which it shares 52% sequence identity. KM+ presents an acetyl‐blocked N‐terminus and is not posttranslationally modified by proteolytic cleavage as is the case for jacalin. Rather,...

Abstract NMR spectroscopic analysis of the C‐terminal Kunitz domain fragment (α3(VI)) from the human α3‐chain of type VI collagen has revealed that the side chain of Trp21 exists in two unequally populated conformations. The major conformation (M) is identical to the conformation observed in the X‐ray crystallographic structure, while the minor conformation (m) cannot structurally be resolved in detail by NMR due to insufficient NOE data. In the present...

Abstract The refolding of four disulfide lysozyme (at pH 5.2, 20 °C) involves parallel pathways, which have been proposed to merge at a near‐native state. This species contains stable structure in the α‐and β‐domains but lacks a functional active site. Although previous experiments have demonstrated that the near‐native state is populated on the fast refolding pathway, its relevance to slow refolding molecules could not be directly...

Abstract Folding of apomyoglobin is characterized by formation of a compact intermediate that contains substantial helicity. To determine whether this intermediate is obligatory or whether the protein can fold directly into the native state via an alternate parallel pathway, we have combined quench‐flow hydrogen‐exchange pulse labeling techniques with electrospray ionization mass spectrometry. The mass spectra of apomyoglobin...

Abstract Binding of the protein Raf to the active form of Ras promotes activation of the MAP kinase signaling pathway, triggering cell growth and differentiation. Raf/Arg89 in the center of the binding interface plays an important role determining Ras–Raf binding affinity. We have investigated experimentally and computationally the Raf‐R89K mutation, which abolishes signaling in vivo. The binding to [γ‐35S]GTP‐Ras of a fusion...

Abstract The thioredoxin action upon the 2‐oxoacid dehydrogenase complexes is investigated by using different thioredoxins, both wild‐type and mutated. The attacking cysteine residue of thioredoxin is established to be essential for the thioredoxin‐dependent activation of the complexes. Mutation of the buried cysteine residue to serine is not crucial for the activation, but prevents inhibition of the complexes, exhibited by the...

Abstract The structure of the trigonal crystal form of bovine β‐lactoglobulin variant B at pH 7.1 has been determined by X‐ray diffraction methods at a resolution of 2.22 Å and refined to values for R and Rfree of 0.239 and 0.286, respectively. By comparison with the structure of the trigonal crystal form of bovine β‐lactoglobulin variant A at pH 7.1, which was determined previously [Qin BY et al., 1998, Biochemistry 37:14014—14023], the...

Abstract Electrostatic interactions are often critical for determining the specificity of protein‐protein complexes. To study the role of electrostatic interactions for assembly of helical bundles, we previously designed a thermostable, heterotrimeric coiled coil, ABC, in which charged residues were employed to drive preferential association of three distinct, 34‐residue helices. To investigate the basis for heterotrimer...

Abstract The X‐ray crystal structure of the human α‐thrombin‐hirunorm IV complex has been determined at 2.5 Å resolution, and refined to an R‐factor of 0.173. The structure reveals an inhibitor binding mode distinctive of a true hirudin mimetic, which justifies the high inhibitory potency and the selectivity of hirunorm IV. This novel inhibitor, composed of 26 amino acids, interacts through the N‐terminal end with the α‐thrombin...

Abstract In addition to the Cys‐Xaa‐Xaa‐Cys motif at position 30—33, DsbA, the essential catalyst for disulfide bond formation in the bacterial periplasm shares with other oxidoreductases of the thioredoxin family a cis‐proline in proximity of the active site residues. In the variant DsbAP151A, this residue has been changed to an alanine, an almost isosteric residue which is not disposed to adopt the cis conformation. The...

Abstract The mechanism of the disulfide‐bond forming enzyme DsbA depends on the very low pKa of a cysteine residue in its active‐site and on the relative instability of the oxidized enzyme compared to the reduced one. A thermodynamic cycle has been used to correlate its redox properties to the difference in the free energies of folding (ΔΔGred/ox) of the oxidized and reduced forms. However, the relation was proved unsatisfied for a number of DsbA variants....

Abstract Calmodulin (CaM) is a 148‐residue regulatory calcium‐binding protein that activates a wide range of target proteins and enzymes. Calcium‐saturated CaM has a bilobal structure, and each domain has an exposed hydrophobic surface region where target proteins are bound. These two “active sites” of calmodulin are remarkably rich in Met residues. Here we have biosynthetically substituted (up to 90% incorporation) the unnatural...

Abstract β‐Galactosidase (lacZ) from Escherichia coli is a 464 kDa homotetramer. Each subunit consists of five domains, the third being an α/β barrel that contains most of the active site residues. A comparison is made between each of the domains and a large set of proteins representative of all structures from the protein data bank. Many structures include an α/β barrel. Those that are most similar to the α/β barrel of E. coli β‐galactosidase...

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