Wiggly bonds

When we don t show bold and dashed bonds to indicate the three-dimensional structure of the molecule, we mean that we are talking about both enantiomers of the molecule. Another useful way of representing this is with wiggly bonds. Wiggly bonds are in fact slightly ambiguous chemists use them to mean, as they do here, both stereoisomers, but also to mean just one stereoisomer, but unknown stereochemistry. 

The wiggly bonds usually mean that the stereochemistry is unknown or that the compound is a mixture. Here they also mean that it doesn t matterl... 

Schematic representation of two-polymer molecule correlation pathways. The wiggly bonds denote long range chemical bonding pair correlations due to chain connectivity, while the short solid line denotes the spatially local dii correlation function. There are of order a + bN pair contacts between two interpenetrating polymer chains of degree rf pcdymerization N which are embedded in a correlation volume of linear dimension R, oc N . Here dp is the mass fractal dimension of the polymer, 0 = 2 — (D/dp), D is the spatial dimension, and a and b are numerical constants of order unity... 

The sign for a disconnection on a molecule is some sort of wiggly line across the bond being disconnected. You can draw this line in any way you like within reason. The reaction arrow is the implies arrow from logic. The argument is that the existence of any ester implies that it can be made from an acid and an alcohol. 

Substrate Affinity. Enzyme-substrate affinity, as estimated by the Michaelis constant (Km), is affected also by habitat temperature (37). In many cases, the temperature range at which the Michaelis constant is minimal coincides closely with the temperature of the organism s native environment. Wiggs (43) observed that the Km of thyroid protease from burbot is lower for winter fish than for summer fish. Hofer et al. (44) also showed that the Km of trypsin from various species, including fish, correlated with the temperature preferendum of each species. The response of Km to temperature appears to relate to the balance of electrostatic and hydrophobic interactions of the active site with substrate and intramolecular bonds within the enzyme (38,39,45,46,47). 

The way we have represented some of these molecules may be unfamiliarto you we have shown stereochemistry (whether bonds come out of the paper or into it— the wiggly lines indicate a mixture of both) and, for the cyclic glucose, conformation (the actual shape the molecules adopt). These are very important in the sugars we devote Chapter 16 to stereochemistry and Chapter IB to conformation. 

If the compound 26 is a racemate with only the one chiral centre then the bonds are best drawn as ordinary straight lines. This implies a racemate - that there are equal amounts of the two enantiomers (S) -26 and (R)-26. There is no need to draw a wiggly line, for instance. 

Consider a racemate with one chiral centre such as 29. We do not define the stereochemistry since there is only one centre. Note that the bond is not bold or hashed or even wiggly. If we reduce this in a stereoselective reaction so that anti-21 results then we draw in the relative stereochemistry. Even though the product is a racemate, and we ve added the symbol to avoid any confusion, we must define the relative stereochemistry. Of course, we could equally have drawn the other enantiomer 27a. 

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