temporary banners

 



 

Journal Issue - Volume 2 Issue 8 (August 1993)

Abstract Adrenergic receptors for adrenaline and noradrenaline belong to the large multigenic family of receptors coupled to GTP‐binding proteins. Three pharmacologic types have been identified: α1‐, α2‐, and β‐adrenergic receptors. Each of these has three subtypes, characterized by both structural and functional differences. The α2 and β receptors are coupled negatively and positively, respectively, to adenylyl cyclase via Gi or Gs regulatory...

Abstract A series of six chimeric proteins, composed of fragments corresponding to either one or the other of the growth factor‐associated mouse glandular kallikreins–epidermal growth factor binding protein (EGF‐BP) and the γ‐subunit of nerve growth factor (γ‐NGF)–were expressed in Escherichia coli and isolated, and their kinetic properties were characterized. The assembly of these synthetic proteases involved the substitution of...

Abstract Six chimeric constructs of the sequentially similar growth factor‐associated kallikreins–epidermal growth factor binding protein (EGF‐BP) and the γ‐subunit of nerve growth factor (γ‐NGF)–have been expressed, and their ability to generate complexes with epidermal growth factor (EGF) and β‐NGF, analogous to the high molecular weight forms (7S NGF and HMW‐EGF) found in the mouse submaxillary gland, evaluated. The chimeras are...

Abstract We have predicted the three‐dimensional structures of the serine protease subunits (γ‐NGF, α‐NGF, and EGF‐BP) of the high molecular weight complexes of nerve growth factor (7S NGF) and epidermal growth factor (HMW‐EGF) from the mouse submandibular gland (from the X‐ray crystal structures of two related glandular kallikreins). The conformations of three of the six loops surrounding the active site are relatively well defined...

Abstract We recently developed a rapid loop closure algorithm in which bond lengths are scaled to constrain the ends of a segment to match a known distance and then gradually relaxed to their standard values, with boundary constraints maintained. Although the algorithm predicted the Zif286 zinc‐finger loop to within approximately 2 Å, it had a serious limitation that made its more general use tentative: it omitted the atomic...

Abstract Libraries of random sequence polypeptides are useful as sources of unevolved proteins, novel ligands, and potential lead compounds for the development of vaccines and therapeutics. The expression of small random peptides has been achieved previously using DNA synthesized with equimolar mixtures of nucleotides. For many potential uses of random polypeptide libraries, concerns such as avoiding termination codons and matching...

Abstract The form of succinyl‐CoA synthetase found in mammalian mitochondria is known to be an αβ dimer. Both GTP‐and ATP‐specific isozymes are present in various tissues. We have isolated essentially identical complementary DNA clones encoding the β subunit of pig heart succinyl‐CoA synthetase from both newborn and adult tissues. These cDNAs include a 1.4‐kb sequence encoding the cytoplasmic precursor to the β subunit comprised of...

Abstract Circular dichroism was used to study the folding of αα‐tropomyosin and AcTM43, a 43‐residue peptide designed to serve as a model for the N‐terminal domain of tropomyosin. The sequence of the peptide is AcMDAIKKKMQMLKLDVENLLDRLEQLEADLKALEDRYKQLEGGC. The peptide appeared to form a coiled coil at low temperatures (<25 °C) in buffers with physiological ionic strength and pH. The folding and unfolding of the peptide, however,...

Abstract The three‐dimensional structure of human basic fibroblast growth factor has been refined to a crystallographic residual of 16.1% at 1.6 Å resolution. The structure has a Kunitz‐type fold and is composed of 12 antiparallel β‐strands, 6 of which form a β‐barrel. One bound sulfate ion has been identified in the model, hydrogen bonded to the side chains of Asn 27, Arg 120, and Lys 125. The side chain of Arg 120 has two...

Abstract The T4 lysozyme mutant Ser 117 → Phe was isolated fortuitously and found to be more thermostable than wild‐type by 1.1–1.4 kcal/mol. In the wild‐type structure, the side chain of Ser 117 is in a sterically restricted region near the protein surface and forms a short hydrogen bond with Asn 132. The crystal structure of the S117F mutant shows that the introduced Phe side chain rotates by about 150° about the Cα–Cβ bond...

Abstract The conformation and stability of a recombinant mouse interleukin‐6 (mIL‐6) has been investigated by analytical ultracentrifugation, fluorescence spectroscopy, urea‐gradient gel electrophoresis, and near‐ and far‐ultraviolet circular dichroism. On decreasing the pH from 8.0 to 4.0, the tryptophan fluorescence of mIL‐6 was quenched 40%, the midpoint of the transition occurring at pH 6.9. The change in fluorescence quantum...

Abstract Defensins, a family of cationic peptides isolated from mammalian granulocytes and believed to permeabilize membranes, were tested for their ability to cause fusion and lysis of liposomes. Unlike α‐helical peptides whose lytic effects have been extensively studied, the defensins consist primarily of β‐sheet. Defensins fuse and lyse negatively charged liposomes but display reduced activity with neutral liposomes. These and...

Abstract Most Cys2His2 zinc finger proteins contain tandem arrays of metal binding domains. The tandem nature of these arrays suggests that metal binding by these domains may not be independent but rather that metal binding may occur in a cooperative manner. This is especially true in light of the crystal structure of a three zinc finger array bound to DNA that revealed several types of interactions between domains. To address this...

Abstract A seminal difference exists between the two types of chains that constitute the tetrameric hemoglobin in vertebrates. While α chains associate weakly into dimers, β chains self‐associate into tightly assembled tetramers. While heterotetramers bind ligands cooperatively with moderate affinity, homotetramers bind ligands with high affinity and without cooperativity. These characteristics lead to the conclusion that the β4...

Page:   1 2 Next