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Cockburn RA Siegmann R Payne KA Beuermann S McKenna TF Hutchinson RA 《Biomacromolecules》2011,12(6):2319-2326
The propagation kinetics and copolymerization behavior of the biorenewable monomer γ-methyl-α-methylene-γ-butyrolactone (MeMBL) are studied using the pulsed laser polymerization (PLP)/size exclusion chromatography (SEC) technique. The propagation rate coefficient for MeMBL is 15% higher than that of its structural analogue, methyl methacrylate (MMA), with a similar activation energy of 21.8 kJ·mol(-1). When compared to MMA, MeMBL is preferentially incorporated into copolymers when reacted with styrene (ST), MMA, and n-butyl acrylate (BA); the monomer reactivity ratios fit from bulk MeMBL/ST, MeMBL/MMA, and MeMBL/BA copolymerizations are r(MeMBL) = 0.80 ± 0.04 and r(ST) = 0.34 ± 0.04, r(MeMBL) = 3.0 ± 0.3 and r(MMA) = 0.33 ± 0.01, and r(MeMBL) = 7.0 ± 2.0 and r(BA) = 0.16 ± 0.03, respectively. In all cases, no significant variation with temperature was found between 50 and 90 °C. The implicit penultimate unit effect (IPUE) model was found to adequately fit the composition-averaged copolymerization propagation rate coefficient, k(p,cop), for the three systems. 相似文献
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Prions represent a new class of infectious agents. The pathogenic prion protein (PrPSc) is known as the trigger of bovine transmissible spongiform encephalopathy (TSE). By contrast, an oral transmission of PrPSc and an ensuing infection seems to be blocked in non-ruminants such as pigs. Several investigations postulate that the ribosomal protein SA (RPSA) previously named 37-kDa laminin receptor precursor (LRP)/67-kDa laminin receptor (LR) is the candidate for binding and internalization of externally added cellular prion protein in the gut. We isolated a porcine ribosomal protein SA cDNA that consists of 1064 bp with an open reading frame of 885 bp encoding a 295 aa protein. The alignment of vertebrate ribosomal protein SA sequences displayed interspecies differences between cattle and pigs at positions 241 and 272 in the putative indirect PrP interaction site (aa 180-285) on RPSA. A PAC library screen revealed the existence of two processed ribosomal protein SA pseudogenes (RPSAP1 and RPSAP3) and of one non-processed pseudogene (RPSAP2). The pseudogenes have been assigned to SSC6 and SSC1 by hybrid panel analyses and FISH. Compared with the porcine cDNA 3, 7, and 13 insdels, 36, 25, and 57 single nucleotide exchanges and 6, 10, and 8 premature stop codons have been deciphered for RPSAP1, RPSAP2, and RPSAP3. In the 5', 3', and intron like regions, 2 (RPSAP1), 10 (RPSAP2), and 4 (RPSAP3) repeats have been detected. Basically, the repeats belong to one of the class/family LINE/L1, SINE/tRNA-Glu and DNA/MER1_type. We conclude that the pig genome contains multiple copies of the RPSA sequence probably as a consequence to maintain the multifunctionality of the mature protein. 相似文献
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Schalk Robert Braun Frank Frank Rudolf Rädle Matthias Gretz Norbert Methner Frank-Jürgen Beuermann Thomas 《Bioprocess and biosystems engineering》2017,40(10):1519-1527
Bioprocess and Biosystems Engineering - The monitoring of microbiological processes using Raman spectroscopy has gained in importance over the past few years. Commercial Raman spectroscopic... 相似文献
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