Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phase structures and enzymatic degradation of poly(l-lactide) (PLLA)/atactic poly(3-hydroxybutyrate) (ata-PHB) blends with different compositions were characterized by using atomic force microscopy (AFM). Differential scanning calorimetry (DSC) thermograms of PLLA/ata-PHB blends with different compositions showed two glass transition temperatures, indicating that the PLLA/ata-PHB blends are immiscible in the melt. Surface morphologies of the thin films for PLLA/ata-PHB blends were determined by AFM. Phase separated morphology was recognized from the AFM topography and phase images. The domain size of the components was dependent on the blend ratio. Enzymatic degradation of the PLLA/ata-PHB blends was performed by using both PHB depolymerase and proteinase K. Either PLLA or ata-PHB domains were eroded depending on the kinds of enzyme. Surface morphologies after enzymatic degradation have revealed the phase structure along the depth direction. Enzymatic adsorption of PHB depolymerase was examined on the surface of PLLA/ata-PHB blends. The enzyme molecules were found on both domains of the binary blends. The larger number of enzyme molecules was found on the PLLA domains relative to those on the ata-PHB domains, suggesting the higher affinity of the enzyme against PLLA domain.
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PMID:Phase structure and enzymatic degradation of poly(L-lactide)/atactic poly(3-hydroxybutyrate) blends: an atomic force microscopy study. 1676 15

Thin films of poly(L-lactide) (PLLA)/atactic poly(3-hydroxybutyrate) (ataPHB) blends with different miscibility were prepared and characterized by using differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The DSC analysis suggested that the blend thin films exhibited different phase structures, such as miscible, partially miscible, and immiscible depending on the blending ratio as well as molecular weight of ataPHB component. The different miscibility was further confirmed by the surface morphological observation by AFM. Both the immiscible and partially miscible blends of PLLA/ataPHB revealed the formation of phase-separated morphology of PLLA and ataPHB components, whereas the homogeneous surface morphology was observed for the miscible blend. On the basis of the changes in the depth profile from the surface level of the thin films, the enzymatic degradation rates of the PLLA and ataPHB domains were determined in the presence of either PHB depolymerase or proteinase K, respectively. The erosion rate of PLLA/ataPHB blends was strongly dependent on the blend composition and the degree of dispersion of the two components. The enzymatic degradation behaviors were discussed in terms of phase structure, molecular mobility, and retardation effect of the components in the blends.
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PMID:Effect of phase structure on enzymatic degradation in poly(L-lactide)/atactic poly(3-hydroxybutyrate) blends with different miscibility. 1929 77