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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 51 (1992), S. 213-217 
    ISSN: 1432-0827
    Keywords: Porcine secretory enamel ; Degradation of amelogenin ; Proteinases ; 25kDa amelogenin ; Enzymography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In the outermost layer of porcine-developing enamel adjacent to the ameloblasts in the secretory stage, the activities of two proteinases having molecular masses of 76 and 78kDa were detected by enzymography using gelatin as a substrate. On the other hand, high activities of known 30 and 34kDa proteinases were localized in the inner layer of the enamel. The 76kDa proteinase cleaved the carboxylterminal peptide of porcine 25kDa amelogenin to convert it to 20kDa amelogenin. The 78kDa proteinase also acted on the 25kDa amelogenin similarly, but its activity was weak. The results indicate that the 25kDa amelogenin synthesized and secreted by ameloblasts is converted to 20kDa amelogenin by the action of proteinase localized in the outermost layer of the secretory enamel, and then further degraded by the proteinases in the inner layer of the enamel associated with the increase of mineralization.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 55 (1994), S. 426-435 
    ISSN: 1432-0827
    Keywords: Dentin mineralization ; Enzymography ; Geatinases ; Proteoglycanases ; Protoglycans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Samples containing predentin and mineralized dentin involving the mineralized front (newly formed dentin) were prepared by scraping developing porcine teeth after odontoblastic cell debris had been removed from the predentin surfaces. An extract was obtained separately from the matrices of predentin and of the newly formed dentin with a 4 M guanidine solution before and after demineralization with acetic acid solution. Enzymography detected 56 and 61 kDa gelatinases and 25 kDa proteoglycanase as neutral metalloproteinases in both extracts and proved them to be in an active form. Approximately half of the 56 and 61 kDa gelaunases binds to collagen fibers in predentin matrix. Three high molecular weight proteoglycans (70–85 kDa, 130–180 kDa, and 290 kDa) were found in the predentin matrix, but not in the newly formed dentin. The proteoglycanases in predentin degraded 290 kDa proteoglycan, if incubated together with calcium (Ca) ions. The results of this investigation indicate that active proteoglycanases with existed in the predentin perform no substantial work in proteoglycan degradation because the Ca ions are masked in the predentin matrix by coexisting proteoglycans. When mineralization occurs, however, they can degrade the proteoglycan at the mineralization front because excess Ca ions may be supplied via odontoblastic processes.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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