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Journal Issue - Volume 9 Issue 9 (2000)

  • Collectin structure: A review

  • Kjell Håkansson, Kenneth B. M. Reid
  • Published in Wiley Interscience on Dec 31, 2008
  • DOI: 10.1110/ps.9.9.1607 (p 1607-1617)

Abstract Colleetins are animal calcium dependent lectins that target the carbohydrate structures on invading pathogens, resulting in the agglutination and enhanced clearance of the microorganism. These proteins form trimers that may assemble into larger oligomers. Each polypeptide chain consists of four regions: a relatively short N‐terminal region, a collagen like region, an α‐helical coiled‐coil, and the lectin domain. Only...

Abstract The cerebroside‐sulfate activator protein (CSAct or Saposin B) is a small water‐soluble glycoprotein that plays an essential role in the metabolism of certain glycosphingolipids, especially sulfatide. Deficiency of CSAct in humans leads to sulfatide accumulation and neurodegenerative disease. CSAct activity can be measured in vitro by assay of its ability to activate sulfatide‐sulfate hydrolysis by arylsulfatase A. CSAct...

Abstract Aspartic proteinases share a conserved network of hydrogen bonds (termed “fireman's grip”), which involves the hydroxyl groups of two threonine residues in the active site Asp‐Thr‐Gly triplets (Thr26 in the case of human immunodeficiency virus type 1 (HIV‐1) PR). In the case of retroviral proteinases (PRs), which are active as symmetrical homodimers, these interactions occur at the dimer interface. For a systematic analysis...

Abstract The potential for engineering stable proteins with multiple amino acid substitutions was explored. Eleven lysine, five methionine, two tryptophan, one glycine, and three threonine substitutions were simultaneously made in barley chymotrypsin inhibitor‐2 (CI‐2) to substantially improve the essential amino acid content of the protein. These substitutions were chosen based on the three‐dimensional structure of CI‐2 and an...

Abstract An important goal of protein design is to understand the forces that stabilize a particular fold in preference to alternative folds. Here, we describe an extension of earlier studies in which we successfully designed a stable, native‐like helical protein that is 50% identical in sequence to a predominantly β‐sheet protein, the B1 domain of Streptococcal IgG‐binding protein G. We report the characteristics of a series of variants of our...

Abstract The rate and extent of hydrogen/deuterium (H/D) exchange into purine nucleoside phosphorylase (PNP) was monitored by electrospray ionization mass spectrometry (ESI‐MS) to probe protein conformational and dynamic changes induced by a substrate analogue, products, and a transition state analogue. The genetic deficiency of PNP in humans is associated with severe T‐cell immunodeficiency, while B‐cell immunity remains...

Abstract Human lysozyme has a structure similar to that of hen lysozyme and differs in amino acid sequence by 51 out of 129 residues with one insertion at the position between 47 and 48 in hen lysozyme. The backbone dynamics of free or (NAG)3‐bound human lysozyme has been determined by measurements of 15N nuclear relaxation. The relaxation data were analyzed using the Lipari‐Szabo formalism and were compared with those of hen lysozyme, which...

Abstract The unrefined fold of Escherichia coli β‐galactosidase based on a monoclinic crystal form with four independent tetramers has been reported previously. Here, we describe a new, orthorhombic form with one tetramer per asymmetric unit that has permitted refinement of the structure at 1.7 Å resolution. This high‐resolution analysis has confirmed the original description of the structure and revealed new details. An essential...

Abstract The activation domain of human procarboxypeptidase A2 (ADA2h) aggregates following thermal or chemical denaturation at acidic pH. The aggregated material contains well‐defined ordered structures with all the characteristics of the fibrils associated with amyloidotic diseases. Variants of ADA2h containing a series of mutations designed to increase the local stability of each of the two helical regions of the protein have...

Abstract The bacterial toxin colicin E9 is secreted by producing Escherichia coli cells with its 9.5 kDa inhibitor protein Im9 bound tightly to its 14.5 kDa C‐terminal DNase domain. Double‐ and triple‐resonance NMR spectra of the 24 kDa complex of uniformly 13C and 15N labeled Im9 bound to the unlabeled DNase domain have provided sufficient constraints for the solution structure of the bound Im9 to be determined. For the final ensemble of 20...

Abstract A molecular dynamics simulation approach has been utilized to understand the unusual fluorescence emission decay observed for β‐glycosidase from the hyperthermophilic bacterium Solfolobus sulfataricus (Sβgly), a tetrameric enzyme containing 17 tryptophanyl residues for each subunit. The tryptophanyl emission decay of (Sβgly) results from a bimodal distribution of fluorescence lifetimes with a short‐lived component centered at 2.5 ns...

Abstract Transcription factor IIB (TFIIB) is an essential component in the formation of the transcription initiation complex in eucaryal and archaeal transcription. TFIIB interacts with a promoter complex containing the TATA‐binding protein (TBP) to facilitate interaction with RNA polymerase II (RNA pol II) and the associated transcription factor IIF (TFIIF). TFIIB contains a zinc‐binding motif near the N‐terminus that is directly...

Abstract Comparative protein structure prediction is limited mostly by the errors in alignment and loop modeling. We describe here a new automated modeling technique that significantly improves the accuracy of loop predictions in protein structures. The positions of all nonhydrogen atoms of the loop are optimized in a fixed environment with respect to a pseudo energy function. The energy is a sum of many spatial restraints that...

Abstract We report here that in vitro exposure of monomeric actin to hydrogen peroxide leads to a conversion of 6 of the 16 methionine residues to methionine sulfoxide residues. Although the initial effect of H2O2 on actin is the oxidation of Cys374, we have found that Met44, Met47, Met176, Met190, Met269, and Met355 are the other sites of the oxidative modification. Met44 and Met47 are the methionyl sites first oxidized. The methionine...

Abstract Bile‐salt activated lipase (BAL) is a páncreatic enzyme that digests a variety of lipids in the small intestine. A distinct property of BAL is its dependency on bile salts in hydrolyzing substrates of long acyl chains or bulky alcoholic motifs. A crystal structure of the catalytic domain of human BAL (residues 1‐538) with two surface mutations (N186D and A298D), which were introduced in attempting to facilitate...

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