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Microbial Transglutaminase Modifies Gel Properties of Porcine Collagen
Erwanto, Y.,Kawahara, S.,Katayama, K.,Takenoyama, S.,Fujino, H.,Yamauchi, K.,Morishita, T.,Kai, Y.,Watanabe, S.,Muguruma, M. Asian Australasian Association of Animal Productio 2003 Animal Bioscience Vol.16 No.2
We studied the gel properties of porcine collagen with microbial transglutaminase (MTGase) as a catalyst. A creep meter was used to measure the mechanical properties of gel. The results showed samples with high concentration of MTGase gelled faster than those with a low concentration of MTGase. The gel strength increased with incubation time and the peaks of breaking strength for 0.1, 0.2 and 0.5% MTGase were obtained at 40, 20 and 10 min incubation time, respectively. According to SDS-PAGE, the MTGase was successfully created a collagen polymer with an increase in molecular weight, whereas no change in formation was shown without MTGase. The sample with 0.5% MTGase began to polymerize after 10 or 20 min incubation at $50^{\circ}C$, and complete polymerization occurred after 40-60 min incubation. Scanning electron microscopic analysis revealed that the gel of porcine collagen in the presence of MTGase produced an extremely well cross-linked network. The differential scanning calorimetric analysis showed the peak thermal transition of porcine collagen gel was at $36^{\circ}C$, and that with MTGase no peak was detected during heating from 20 to $120^{\circ}C$. The melting point of porcine collagen gel could be controlled by MTGase concentration, incubation temperature and protein concentration. Knowledge of the structural and physicochemical properties of porcine collagen gel catalyzed with MTGase could facilitate their use in food products.
Kim, Y D,Park, K-G,Morishita, R,Kaneda, Y,Kim, S-Y,Song, D-K,Kim, H-S,Nam, C-W,Lee, H C,Lee, K-U,Park, J-Y,Kim, B-W,Kim, J-G,Lee, I-K Nature Publishing Group 2006 Gene Therapy Vol.13 No.3
Insulin gene therapy in clinical medicine is currently hampered by the inability to regulate insulin secretion in a physiological manner, the inefficiency with which the gene is delivered, and the short duration of gene expression. To address these issues, we injected the liver of streptozotocin-induced diabetic rats with hemagglutinating virus of Japan-envelope (HVJ-E) vectors containing Epstein–Barr virus (EBV) plasmids encoding the genes for insulin and the GLUT 2 transporter. Efficient delivery of the genes was achieved with the HVJ-E vector, and the use of the EBV replicon vector led to prolonged hepatic gene expression. Blood glucose levels were normalized for at least 3 weeks as a result of the gene therapy. Cotransfection of GLUT 2 with insulin permitted the diabetic rats to regulate their blood glucose levels upon exogenous glucose loading in a physiologically appropriate manner and improved postprandial glucose levels. Moreover, cotransfection with insulin and GLUT 2 genes led to in vitro glucose-stimulated insulin secretion that involved the closure of K<SUB>ATP</SUB> channels. The present study represents a new way to efficiently deliver insulin gene in vivo that is regulated by ambient glucose level with prolonged gene expression. This may provide a basis to overcome limitations of insulin gene therapy in humans.Gene Therapy (2006) 13, 216–224. doi:10.1038/sj.gt.3302644; published online 22 September 2005