Carboxylated polyethyleneglycol

Carboxylated polyethyleneglycol, 45 178 Carboxylates, see also specific compounds binuclear, structure of, 20 293-299 bridge, 20 292, 293... 

Figure 5 Starting from natural mRNA, a cDNA library (A blue) is produced and like ribosomal display, the cDNA is transcribed into mRNA (B) with no stop codons. The 3 -end of each mRNA molecule is ligated to a short synthetic DNA linker (C) and sometimes a polyethyleneglycol spacer, which terminates with a puramycin molecule (small red sphere). The ligation is stabilized by the addition of psoralen (green clamp), which is photoactivated to covalently join both strands. Addition of crude polysomes or purified ribosomes (D) results in translation of the mRNA into protein, but the ribosome stalls at the mRNA-DNA junction. Since there are no stop codons, release factors cannot function and instead the puromycin enters the A-site of the ribosome (A). Because puramycin is an analog of tyrosyl-tRNA, the peptidyl transferase subunit catalyzes amide bond formation between the puromycin amine and the peptide carboxyl terminus, but is unable to hydrolyze the amide link (which should be an ester in tyrosyl-tRNA) to release the dimethyladenosine. The ribosome is dissociated to release the mRNA-protein fusion (E), which is protected with complementary cDNA using RT-PCR (F). The mRNA library can then be selected against an immobilized natural product probe (G), nonbinding library members washed away and the bound mRNA (H) released with SDS. PCR amplification of the cDNA provides a sublibrary (A) for another round of selection or for analysis/ sequencing.

Fig. 7. Polyethyleneglycol glycosides with terminal functional group of (A) cyclic acetal group [86] (B) amino group [31] (C) carboxyl group [87].

Aqueous carbodiimide chemistry is widely used to couple carboxylic groups on alginate with molecules containing primary or secondary amines (d Ayala et al., 2008). Several examples are reported in which alginate is nsed in combination with polyethyleneglycol (PEG). Chanical modification of alginate with acrylic acids through... 

AM-BIO membranes (Asahi Medical, Japan), a hydrogel layer made of hydrophilic leashes protruding into the blood is formed at the surface of RC membranes by esterification of polyethyleneglycol acid through its carboxyl moiety with the hydroxyl groups in the cellulosic backbone. These membranes are available with different surface roughness in low- and high-flux devices and exhibit low platelet adhesion and complement activation (Fukuda et al., 1999). 

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