Time filter

Source Type

Jus S.,Austrian Center of Industrial Biotechnology | Jus S.,University of Graz | Stachel I.,Research Institute for Leather and Plastic Sheeting | Schloegl W.,Ludwig Maximilians University of Munich | And 7 more authors.
Materials Science and Engineering C | Year: 2011

Oxidation of acid soluble collagen (ASC), collagen suspension and BrCN-peptides (BrCN-P) with tyrosinases from B. obtusa (BoT1, BoT2) and A. bisporus (AbT) and laccases from T. versicolor (TvL) and T. hirsuta (ThL) resulted in UV/VIS peaks at 475 nm and 305 nm indicating formation of reactive o-quinones and cross-linked components. Concomitant oxygen consumption was higher for the low molecular weight enzymes (TvL and BoT2) indicating limited accessibility. SDS-PAGE and SEC bands at higher MW demonstrated the formation of cross-linked material. LC-MS/MS analysis suggested the involvement of tyrosine residues in cross-linking without major changes of sequence similarities to untreated collagen. However, an increase of the SEC α-peak together with a decrease of β-peak and the 1235/1450 cm- 1 ratio (FTIR) indicated partial degradation. Crosslinking was enhanced by phenolic molecules such as catechine which lead to increased denaturation temperature and reduced degradation by microbial collagenase. The tensile strength was increased whereas resistance to compressive forces was not influenced. © 2011 Elsevier B.V. All rights reserved. Source

Schloegl W.,Ludwig Maximilians University of Munich | Klein A.,Ludwig Maximilians University of Munich | Furst R.,Ludwig Maximilians University of Munich | Leicht U.,Ludwig Maximilians University of Munich | And 8 more authors.
European Journal of Pharmaceutics and Biopharmaceutics | Year: 2012

In the present study, we developed an enzyme-linked immunosorbent assay (ELISA) for microbial transglutaminase (mTG) from Streptomyces mobaraensis to overcome the lack of a quantification method for mTG. We further performed a detailed follow-on-analysis of insoluble porcine collagen type I enzymatically modified with mTG primarily focusing on residuals of mTG. Repeated washing (4×) reduced mTG-levels in the washing fluids but did not quantitatively remove mTG from the material (p < 0.000001). Substantial amounts of up to 40% of the enzyme utilized in the crosslinking mixture remained associated with the modified collagen. Binding was non-covalent as could be demonstrated by Western blot analysis. Acidic and alkaline dialysis of mTG treated collagen material enabled complete removal the enzyme. Treatment with guanidinium chloride, urea, or sodium chloride was less effective in reducing the mTG content. © 2011 Elsevier B.V. All rights reserved. Source

Stachel I.,Research Institute for Leather and Plastic Sheeting | Schwarzenbolz U.,TU Dresden | Henle T.,TU Dresden | Meyer M.,Research Institute for Leather and Plastic Sheeting
Biomacromolecules | Year: 2010

Collagen is a popular biomaterial. To deal with its lack of thermal stability and its weak resistance to proteolytic degradation, collagen-based materials are stabilized via different cross-linking procedures. Regarding the potential toxicity of residual cross-linking agents, enzyme-mediated cross-linking would provide an alternative and nontoxic method for collagen stabilization. The results of this study show that type I collagen is a substrate for mTG. However, ε-(γ-glutamyl)lysine cross-links are only incorporated at elevated temperatures when the protein is partially or completely denatured. A maximum number of 5.4 cross-links per collagen monomer were found for heat-denatured collagen. Labeling with the primary amine monodansylcadaverine revealed that at least half of the cross-links are located within the triple helical region of the collagen molecule. Because the triple helix is highly ordered in its native state, this finding might explain why the glutamine residues are inaccessible for mTG under nondenaturing conditions. © 2010 American Chemical Society. Source

Discover hidden collaborations