Poly enzymatic degradation

Spyros A, Kimmich R, Briese BH, Jendrossek D (1997) H NMR imaging study of enzymatic degradation in poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hy-droxyvderate). Macromolecdes 30 8218-8225... 

Akagi T, Higashi M, Kaneko T et al (2005) In vitro enzymatic degradation of nanoparticles prepared from hydrophobically-modified poly (y-glutamic acid). Macromol Biosci 5 598-602... 

Both the cap and the poly-A tail play a vital part in initiating eukaryotic translation (see p. 250). They help position the ribosome correctly on the mRNA near to the starting codon. The protection which the additional nucleotides provide against premature enzymatic degradation appears to be of lesser importance. 

Muller RJ, Schrader H, Profe J et al (2005) Enzymatic degradation of poly(ethylene terephthalate) Rapid hydrolyse using a hydrolase from T. fusca. Macromol Rapid Commun 26 1400-1405... 

Some of recent papers by Ratner et al. [63, 64] revealed that there are significant differences in the surface chemistry of Biomer lots. The surface of some lots was dominated by poly(diisopropylaminoethyl methacrylate) (DPAEMA or DIPAM), a high molecular weight UV stabilizer, which was absent from some older lots [65]. Ratner et al. carried out comparative studies on in vitro enzymatic and oxidative degradation of two lots of Biomer, BSU 001 and BSP 067. Lot BSU 001 contains both DPAEMA and an antioxidant, Santowhite powder, while BSP 067 contains only the antioxidant. It was found that DPAEMA retarded the enzymatic degradation process, but accelerated oxidative degradation. 

Brus, C., et al. 2004. Efficiency of polyethylenimines and polyethylenimine-graft-poly(ethylene glycol) block copolymers to protect oligonucleotides against enzymatic degradation. Eur J Pharm Biopharm 57 427. 

Luessen, H.L., et al. 1996. Mucoadhesive polymers in peroral peptide drug delivery. V. Effect of poly(acrylates) on the enzymatic degradation of peptide drugs by intestinal brush border membrane vesicles. Int J Pharm 141 39. 

Bemkop-Schnurch, A., and K. Dundalek. 1996. Novel bioadhesive drug delivery system protecting (poly)peptides from gastric enzymatic degradation. Ini J Pharm 138 75. 

Ren KF, li 1, Shen 1C (2006) Construction and enzymatic degradation of multilayered poly-L-lysine/DNA films. Biomaterials 27 1152-1159... 

Ishiaku, U.S. Pang, K.W. Lee, W.S. Mohd-Ishak, Z.A. Mechanical properties and enzymatic degradation of thermoplastic and granular sogo starch filled poly(epsilon-caprolactone). Eur. Polym. J. 2002, 38, 393-401. 

In the former case, a bacterial or fungal colony on the surface of the material releases an extracellular degrading enzyme which breaks down the polymer chains into smaller units (dimers and ohgomers), which then are absorbed through the microorganisms ceU membrane and metabolised as a source of nutrient (carbon). It has been proposed that this mechanism first hydrolyses the chains of the amorphous phase of poly-(3-hydroxybutyrate) (PHB) and then proceeds to attack the chains in the crystalline state. The enzymatic degradation rate decreases as the crystallinity increases [15, 16]. 

Figure 2. Enzymatic degradation of poly(ADP-ribose).The arrows indicate the covalent bonds that are cleaved by poly(ADP-ribose) glycohydrolase ( ), ADP-ribosyl protein lyase (-- ), and phosphodiesterase (Jl). The reader can work out what the respective reaction products would be in each case (refer also to Figure 1).

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