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  • Cell & Developmental Biology  (1)
  • Enzymes  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Isolation of cDNA clones from an osteosarcoma-ROS17/2.8 library by differential hybridization (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 54 (1994), S. 273-280 
    Details
    ISSN: 0730-2312
    Keywords: differential hybridization ; osteoblastic cDNA ; ROS17/2.8 ; chondrocytes ; calvaria ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have used differential hybridization to isolate and characterize two novel cDNAs expressed in chondrocytes and some osteoblastic cells. A rat osteosarcoma ROS17/2.8 cDNA library was screened and cDNA clones hybridizing strongly to radiolabeled porcine calvaria cDNA but weakly to a control radiolabeled cDNA were isolated. Two clones were obtained - p.6.1 and p.10.15. A radiolabeled probe of p10.15 was shown to hybridize specifically to a 2.3 Kb message RNA from a chondrogenic clonal cell population from rat calvaria-RCJ 3.1C5.18, and the mRNA was downregulated by 1,25 (OH)2D3, which inhibits chondrogenesis in these cells. The other clone, p6.1, was found to hybridize to a 0.95 Kb message that is expressed in rat liver, kidney, lung, muscle, and brain, but not expressed in spleen and expressed only in low levels in thymus.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240540303
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of Enzyme Structure and Activity by Protein EngineeringThe review article is based on a lecture presented at The Third European Symposium on Organic Chemistry (ESOC III) in September, 1983. This work was supported by the Medical Research Council of the UK. (1984)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 23 (1984), S. 467-473 
    Details
    ISSN: 0570-0833
    Keywords: Analytical methods ; Enzymes ; Protein engineering ; Enzyme activity ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure-activity relationships of enzymes can now be analyzed for the first time by the systematic alteration of protein structure. Recent developments in the chemical synthesis of DNA fragments and recombinant DNA technology enable the facile modification of proteins by highly specific mutagenesis of their genes. Kinetic analysis of the mutant enzymes combined with high-resolution structural data from protein X-ray crystallography allow direct measurements on the relationships between structure and function. In particular, the strength and nature of enzyme-substrate interactions and their detailed roles in catalysis and specificity can now be studied. We have developed such analysis of enzyme structure-function by site-directed mutagenesis of the tyrosyl-tRNA synthetase from Bacillus stearothermophilus, concentrating so far on the subtle role of hydrogen bonding in both substrate specificity and catalysis. We find that the energetics of tyrosine and ATP binding must be analyzed in terms of an exchange reaction with solvent water. Based on this idea and structural data, we have engineered an enzyme of improved enzyme-substrate affinity, and there thus appear to be real prospects of engineering proteins of new specificities, activities, and structural properties. We are also using protein engineering to gather direct information on the nature of enzyme catalysis. For example, we find the catalysis of formation of Tyr-AMP from Tyr and ATP is due largely to electrostatic and hydrogen bonding interactions that are stronger in the transition state than in the ground state - a “strain” mechanism rather than acid-base or covalent catalysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198404673
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    Paper (German National Licenses)
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