Terminal moieties chain length

In the PCH polymer, the enthalpy change due to the smectic to isotropic phase increases with an increase of the terminal alkyl chain length. This means that the liquid crystal state is more stabilized by lengthening the alkyl chain as a terminal moiety of the liquid crystalline group. 

This enzyme [EC 2.4.2.30] (also referred to as NAD+ ADP-ribosyltransferase, poly(ADP) polymerase, poly-(adenosine diphosphate ribose) polymerase, and ADP-ribosyltransferase (polymerizing)) catalyzes the reaction of NAD+ with [ADP-D-ribosyl] to produce nicotinamide and [ADP-D-ribosyl]( + i). The ADP-d-ribosyl group of NAD+ is transferred to an acceptor carboxyl group on a histone or on the enzyme itself, and further ADP-ribosyl groups are transferred to the 2 -position of the terminal adenosine moiety, building up a polymer with an average chain length of twenty to thirty units. 

Sex pheromones in the Lepidoptera are multi-component mixtures consisting mostly of olefinic compounds possessing a terminal aldehyde, alcohol, or acetate moiety. Besides functional group differences, the constituents of lepidopteran sex pheromones vary in hydrocarbon chain length and in the specific number, location, and geometry of double bonds. These chemical structures are formed in biosynthetic pathways involving a limited number of enzymatic steps believed to use fatty-acyl thioesters of coenzyme A (acyl-CoA) as substrates. Key reactions are desaturation, limited [3-oxidation, and a small number of terminal functional group modifications (reviewed in Chapter 3). 

The eukaryotic FASs synthesize predominantly the 16-carbon saturated product with smaller amounts of 14- and 18-carbon products. The enzymatic basis of product specificity of the animal FAS has been studied in some detail in G. Hammes and S. Smith s laboratories. The KS has a relatively broad chain-length specificity and is able to transfer efficiently saturated acyl moieties with 2-14 carbon atoms from the phosphopantetheine thiol to the active-site cysteine thiol. However, longer chain-length acyl moieties are transferred between thiols with increasing difficulty [17], In contrast, the chain-terminating thioesterase has very limited ability to remove acyl moieties with less than 16 carbon atoms from the phosphopantetheine thiol (S. Smith, 1978, 1991). Thus the specificities of... 

The ATRP of the methacrylate monomers was performed at 60°C in ethanol solutions and in the presence of the catalyst copper(I) chloride/2,2 bipyridyl (Bipy) (Table 1, Entries 1-4). Copolymers P(ME02MA-co-OEGMA) of various chain-lengths and comonomer compositions were prepared and isolated in high yields. After purification, H NMR analysis confirmed that the formed polymers exhibit a terminal cholesterol moiety. Additionally, as previously demonstrated, the molar fraction of OEGMA in the copolymers was found, in all cases, to be almost equal to the fraction of OEGMA in the initial comonomer feed. Furthermore, SEC measurements in THF indicated that all the copolymers are rather well-defined (Table 1, Entries 1-4). 

The stearoyl-ACP desaturase-oleoyl-ACP hydrolase system has been examined recently in terms of the possibility that these two enzymes are directly involved in chain termination at the Cig level in plants (Ohlrogge et al., 1978b). The requirement for chain termination, namely, a high specificity for the chain length acyl moiety which is to be terminated, is met twice by... 

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