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  • 1
    Electronic Resource
    Electronic Resource
    Role of the pro-α2(I) COOH-terminal region in assembly of type I collagen: Disruption of two intramolecular disulfide bonds in pro-α2(I) blocks assembly of type I collagen (1998)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 71 (1998), S. 233-242 
    Details
    ISSN: 0730-2312
    Keywords: assembly of type I collagen ; COOH-terminal propeptide ; pesin-resistant heterotrimers ; disulfide bonds ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Collagen biosynthesis is a complex process that begins with the association of three procollagen chains. A series of conserved intra- and interchain disulfide bonds in the carboxyl-terminal region of the procollagen chains, or C-propeptide, has been hypothesized to play an important role in the nucleation and alignment of the chains. We tested this hypothesis by analyzing the ability of normal and cysteine-mutated pro-α2(I) chains to assemble into type I collagen heterotrimers when expressed in a cell line (D2) that produces only endogenous pro-α1(I). Pro-α2(I) chains containing single or double cysteine mutations that disrupted individual intra- or interchain disulfide bonds were able to form pepsin resistant type I collagen with pro-α1(I), indicating that individual disulfide bonds were not critical for assembly of the pro-α2(I) chain with pro-α1(I). Pro-α2(I) chains containing a triple cysteine mutation that disrupted both intrachain disulfide bonds were not able to form pepsin resistant type I collagen with pro-α1(I). Therefore, disruption of both pro-α2(I) intrachain disulfide bonds prevented the production and secretion of type I collagen heterotrimers. Although none of the individual disulfide bonds is essential for assembly of the procollagen chains, the presence of at least one intrachain disulfide bond may be necessary as a structural requirement for chain association or to stabilize the protein to prevent intracellular degradation. J.Cell. Biochem. 71:233-242, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Role of the pro-α2(I) COOH-terminal region in assembly of type I collagen: Truncation of the last 10 amino acid residues of pro-α2(I) chain prevents assembly of type I collagen heterotrimer (1998)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 71 (1998), S. 216-232 
    Details
    ISSN: 0730-2312
    Keywords: assembly of type I collagen ; COOH-terminal propeptide ; pepsin-resistant heterotrimers ; interspecies collagen molecule ; thermal stability ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Procollagen (Type I) contains a noncollagenous COOH-terminal propeptide (C-propeptide) hypothesized to be important in directing chain association and alignment during assembly. We previously expressed human pro-α2(I) cDNA in rat liver epithelial cells, W8, that produce only pro-α1(I) trimer collagen (Lim et al. [1994] MatrixBiol. 14: 21-30). In the resulting cell lines, α2(I) assembled with α1(I) forming heterotrimers. Using this cell system, we investigated the importance of the COOH-terminal propeptide sequence of the pro-α2(I) chain for normal assembly of type I collagen. Full-length human pro-α2(I) cDNA was cloned into expression vectors with a premature stop signal eliminating the final 10 amino acids. No triple-helical molecules containing α2(I) were detected in transfected W8 cells, although pro-α2(I) mRNA was detected. Additional protein analysis demonstrated that these cells synthesize small amounts of truncated pro-α2(I) chains detected by immunoprecipitation with a pro-α2(I) antibody. In addition, since the human-rat collagen was less thermostable than normal intraspecies collagen, wild-type and C-terminal truncated mouse cDNAs were expressed in mouse D2 cells, which produced only type I trimers. Results from both systems were consistent, suggesting that the last 10 amino acid residues of the pro-α2(I) chain are important for formation of stable type I collagen. J. Cell. Biochem. 71:216-232, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Cell-specific expression of the α1(I) collagen promoter-CAT transgene in skin and lung: A response to TGF-β subcutaneous injection and bleomycin endotracheal instillation (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 63 (1996), S. 135-148 
    Details
    ISSN: 0730-2312
    Keywords: skin ; lung ; CAT gene expression ; α1(I) collagen promoter ; TGF-β ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Transgenic mice containing a rat collagen α1(I) promoter (3.6 kilobases) fused to the reporter gene chloramphenicol acetyl transferase (CAT) express the reporter gene parallel to endogenous gene in most connective tissues other than vascular tissue [Pavlin et al. (1992): J Cell Biol 116:227-236; Bedalov et al. (1994): J Biol Chem 269:4903-4909]. We have challenged transgenic mice with subcutaneous injections of transforming growth factor-β (TGF-β) or intratracheal instillation of bleomycin. In situ hybridization studies of skin revealed increased CAT expression in the papillary dermis of TGF-β treated animals. In contrast, α1(I) collagen mRNA was expressed throughout the dermis including granulation tissue and reticular dermis. Therefore, the transgenic promoter responds to TGF-β in a subset of dermal fibroblasts. Endotracheal instillation of bleomycin induces lung fibrosis which is thought to be mediated in part by TGF-β. CAT gene expression in lungs was increased 6-8-fold at 2 weeks post bleomycin treatment. In situ hybridization studies revealed focal areas of cells expressing both CAT and collagen genes in the interstitium. However, most regions, especially around airways, contained a subset of cells expressing the endogenous gene with little or no CAT expression as judged by in situ hybridization. These cells could be myofibroblasts that require additional cis-acting elements to activate α1(I) collagen gene expression similar to smooth muscle cells. © 1996 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Thrombin and albumin adsorption to PVA and heparin-PVA hydrogels. 2: Competition and displacement (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 89-95 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Thrombin adsorption to polyvinyl alcohol (PVA) was different from its adsorption to polyethylene (PE) - not so much in amount, but in its affinity. Thrombin was more easily displaced from polyethylene and its adsorption was more readily prevented by prior or simultaneous exposure to albumin. From PVA (or heparin-PVA), only ∼ 30% of the adsorbed protein could be removed by a series of eluents, including even harsh ones such as 2.5M NaOH and 6M guanidine;〉85% could be removed from PE. Thrombin adsorption to PVA was not affected by the presence of BSA in solution or at the surface, but was virtually prevented on PE by preexposure to or adsorption with BSA. Heparin-PVA was not much different than PVA in most of these experiments, but did exhibit a “Vroman effect”. In the absence of fibringen or antithrombin III, there was a maximum in thrombin adsorption from plasma at a plasma concentration of 1%. The behavior on this surface was dependent on both exposure time and protein concentration. These studies highlight the complexity of the interaction between plasma proteins and polymer surfaces (particularly hydrogel surfaces) and the difficulty of obtaining a clear picture of what happens when a single protein interacts with a polymer in the presence of other proteins. © 1993 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820270112
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  • 5
    Electronic Resource
    Electronic Resource
    Permeability of a heparin-polyvinyl alcohol hydrogel to thrombin and antithrombin III (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 673-685 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The diffusivities of thrombin and antithrombin III in a heparin-polyvinyl alcohol hydrogel were estimated and used to demonstrate that diffusion limits the effectiveness of the immobilized heparin in the interior of such hydrogels. Diffusivities were calculated from permeabilities and partition coefficients measured with films in a diffusion chamber apparatus. The diffusion coefficients were estimated to be 6 ± 4 × 10-8 cm2/s for thrombin and 4 ± 2 × 10-8 cm2/s for antithormbin III in 10% gel membranes with or without immobilized heparin. Using the diffusivity of thrombin and a Thiele-type modulus, the effectiveness factor of a spherical heparin-PVA bead used to accelerate the inactivation of thrombin by antithrombin III was found to be 4-9% (diameter range 250-105 μm). While indicating that diffusion of thrombin limited the full utilization of the immobilized heparin, these values for the effectiveness factor could not completely account for the low apparent heparin activity (0.2%) in a thrombin time test of heparin-PVA “beads” (J. Biomed. Mater. Res., 17, 359 (1983)). Other factors such as the immobilization chemistry or the diffusion of thrombin-antithrombin III complex must be considered for a full explanation of the thrombin time results.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820220802
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  • 6
    Electronic Resource
    Electronic Resource
    Thrombin and albumin adsorption to PVA and heparin-PVA hydrogels. I. Single protein isotherms (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 947-958 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: More radiolabeled thrombin was adsorbed to heparin-polyvinyl alcohol (PVA) than to PVA, consistent with a specific interaction with the immobilized heparin. The maximum surface concentration on heparin-PVA was estimated to be ∼450 nmol/m2 with an apparent affinity constant (Ka,) of 2.5μM-1; on PVA, the plateau concentration was 10 nmol/m2 with a Ka 〈 1 nM-1. There was little difference in bovine serum albumin (BSA) adsorption between PVA and heparin PVA. Interestingly, thrombin adsorption to polyethylene was indistinguishable from that to PVA despite the large difference in surface chemistry. BSA adsorbed to polyethylene with higher affinity than to the hydrogels, although the plateau concentrations were comparable. The adsorbed thrombin was biologically inactive at least towards chromogenic substrate, with the residual activity on PVA unaffected by subsequent incubations with antithrombin 111. PVA and heparin-PVA presented a heterogeneous and complex substrate for interaction with proteins. The adsorbed protein was likely present in multiple states depending on the groups with which it interacted.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260709
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