Linkages during

Sprung and Gladstone were the first to show the formation of dibenzyl ether linkages during the condensation of hydroxymethyl phenols, as depicted in Scheme 4c [152], These results have been corroborated by a number of researchers since [128,144,147,148], This condensation was reportedly second-order and takes place at pH conditions near neutral and at temperatures less than 130°C [128,147,153], At temperatures of 160°C the dibenzyl ethers are converted to something else, most likely to methylene linkages and formaldehyde [132],... 

Figure 3.12 Cleavage of ether linkages during sulfite pulping.

Scheme 4 Formation of ether linkages during the copolymerization of epoxides and CO2...

The carbon atom of the C02 formed in this reaction is the same carbon originally introduced into malonyl-CoA from HCO3 by the acetyl-CoA carboxylase reaction (Fig. 21-1). Thus C02 is only transiently in covalent linkage during fatty acid biosynthesis it is removed as each two-carbon unit is added. 

Draw the chemical reaction mechanism for the formation of a phosphodiester linkage during DNA synthesis. Discuss the significance of the pyrophosphate product that is formed. What is the significance of the Mg2+ requirement ... 

This overall reaction is reversible but is driven to completion by the subsequent hydrolysis of PP, to two equivalents of P through the action of ubiquitous pyrophosphatases. Thus, the formation of aminoacyl-tRNA consumes two equivalents of ATP. The energy that ultimately drives the formation of the peptide linkage during protein synthesis is derived from the ester linkage that joins amino acids to tRNA. 

Engel, U., Pertz, O., Fauser, C., Engel, J., David, C. N., and Holstein, T. W. (2001). A switch in disulfide linkage during mini-collagen assembly in hydra nematocyst. EMBOJ. 20, 3063-3073. 

It is conceivable that the natural receptor binding structure for Sendai virus has only one terminal NeuAc residue, but it is also possible that some of the oligosaccharide moieties received a disialosyl linkage during the incubation with the specific sialyltransferase. 

Polyurethanes are named because of the presence of the urethane linkage, which is illustrated in Figure 2.1. Intensive research discovered that there were many modifications that could be made to the chemistry surrounding the urethane linkage. During the 1940s and early 1950s, DuPont and ICI developed castable polyurethanes. 

Head-to-Head and Head-to-Tail Linkages. Errors in the linkages between successive monomeric units of the poljrmers are possible (and always statistically present). The effect of head-to-head (HH) and head-to-tail (HT) bonds in the XPS core levels spectra of substituted polymers have been computed and found at the limit of the sensitivity of the technique (e.g. ). The control of these linkages during the synthesis is difficult and the number of polymers that can be prepared with 100% of HH or HT linkages is small (43). 

Yamaji S, Suzuki A, Kanamori H, Mishima W, Takabayashi M, Fujimaki K, Tomita N, Fujisawa S, Ohno S, Ishigatsubo Y. Possible role of ILK-affixin complex in integrin-c)4oskeleton linkage during platelet aggregation. Biochem. Biophys. Res. Commun. 2002 297 1324-1331. 

F. Dasgupta and P. J. Garegg, Alkyl sulfenyl triflate as activator in the thioglycoside-mediated formation of p-glycosidic linkages during oligosaccharide synthesis, Carbohydr. Res. 777 cl3 (1988). Also see Carbohydr. Res. 202 225 (1990). 

The effect of possible mechanical disruption of covalent linkages during high-shear solubilization of p.g.m. mucins from the gel state (and especially without the presence of 6 Af Gu HQ) was also demonstrated by C lstedt and Sheehan for p.g.m. It has been pointed out, however, that this is not a problem for other laige glycoconjugates, such as proteoglycans. 

---