Amides Circle

Fig. 8. Rephcation. The amino adenosine X and the pentafluorophenyl ester Y form a hydrogen-bonded dimer XY, prior to reaction between the amine and the activated ester groups (shown in the circle). The reaction product is a <7 -amide conformer cis-Z that isomeri2es to the more stable trans- acnide Z. The rephcative process is cataly2ed by the reaction product Z (also referred to as the template). First, a termolecular complex XYZ is formed from X, Y, and Z.

The amide formation reaction (highlighted by the circle) leads to the production of a hydrogen-bonded dimer (ZZ) of the reaction product Z with the template Z. The dimer is in thermodynamic equilibrium with free template in the reaction medium. 

Rgure 6.12 Penicillin G contains two amide linkages (circled in a). The amide linkage to the side chain is secondary and exists in two forms (shown in b). 

Fig. 5 Excess acidity plots according to equation (17) for three amides in aqueous perchloric acid at 45°C (upper lines) and 15°C (lower lines). Open circles, 4-methoxy-benzamide closed circles, 3,4,5-trimethoxybenzamide open triangles, 3-nitrobenzamide. Data from ref. 64 numbers to the right of the dashed lines are log/values.

Figure 5.66 Bond-order-bond-length correlations for amide CO (circles) and CN (squares) bonds in the acetamide X complexes of Fig. 5.64 (see Table 5.27).

Q O Draw the product of each polymerization reaction, and classify the reaction. Then circle and identify any amide or ester bonds in the product. 

The lethal activity of the isobutylamides on C. pipiens is shown in Table II. The amides were dissolved in 0.1% acetone in distilled water to give concentrations of 1-20 ppm. Third-instar C. pipiens were transferred (5 larvae/10 ml test solution) into 1 oz. plastic cups using a 1 x 1-inch circle of ordinary window screen. Each treatment was replicated 4 times and the minimum concentration of each compound which caused 100% mortality (LDioo) within 48 h at 25 C and 16L/8D photoperiod was determined. In a result similar to that found with the artificial diet bioassay with lepidopterous larvae, pellitorine proved to be the most toxic of the assayed amides (LDjqq = 5 ppm). 

Polyacrylamide gels of the two cross-linking levels mentioned above were prepared and cut by the same procedure. The circles were placed in a IN sodium hydroxide solution. Conversion of the amide groups to the carbonyl was evidenced by the... 

In order to test whether our CIRcle cell spectra were dominated by adsorbed protein or protein in solution, we ran spectra of a series of lysozyme solutions ranging in concentration from 0.12 to 102. The IR response of the amide I and II bands at 1653 and 1543 cm-1 is nearly linear with concentration between 5 and 102 lysozyme. However, the IR intensities change very little between 0.1 and 12, strongly suggesting that most of the signal we observe at 0.12 concentration is due to adsorbed lysozyme. Since our study of subtilisin BPN was done at 0.012, we are almost certainly observing only adsorbed species in our ATR spectra. 

Theobromine has one acidic hydrogen for the amide unit (shown above, circled), and theophylline has a much less acidic imidazole N-H bond (also circled above). 

Figure 4.5. Left side. Temperature dependence of the bimodal lifetime distribution parameters of Sulfolobus solfataricus (3-glycosidase. Long-lifetime component (squares) short lifetime component (circles). Right upper side W3/4H dependence on temperature thermal denaturation of Sulfolobus solfataricus p-glycosidase at pD 7.4 (continuous line) and pD 10.0 (dashed line). The lines were obtained by monitoring the amide l width calculated at 3A of the amide height (W3/4H) as a function of the temperature. Right bottom side dependence on temperature for Sulfolobus solfataricus p-glycosidase. (Likhtenshtein et al., 2000). Reproduced with permission.

Figure 9 Conformational energy contour map of N-acetyl-N -methylalanine amide, for x1 = 60°. Locations of minima are indicated by the filled circles. The contour lines are labeled with energy in kcal/mol above the minimum-energy point at (4>,

Fig. 9 Kinetic study of transformation from aldehyde 37C (filled squares), to nitroaldol adduct 39C (open circles) and amide product 40 (open triangles), respectively, followed by NMR spectroscopy. Modified from [57], Reproduced by permission of the Royal Society of Chemistry...

Fig. 4,—Depiction of an N,N-Dialkylamide. [Magnetic action of the amide group on N-alkyl protons. Circles are the possible positions of the a-protons. a = equatorial proton (cis to the amide carbonyl) in the deshielding domain c or e = axial proton (cis to the amide carbonyl) in the shielding domain, o = equatorial proton (trans to the amide carbonyl), c or e = axial proton (trans to the amide carbonyl), for the trans positions of low action. ]...

Fig. 3.7 Adsorption of fibrinogen on an EG2/EG6 gradient at pH 7.4. The incremental changes in ellipsometric thickness (filled circles) and the integrated area of the amide I peak obtained by FTIR-spectroscopy (open circles) are displayed...

Fig.16.3 Subgroups of solvents (a) Squares show monofunctional ethers, circles show amides (b) Squares show halocarbons, circles show alcohols.

Fig. 22.5. Relative peak intensity of and C=0 amide and ester carbons in the R-helix, o)L-helix and -sheet forms as deconvoluted computer fitting (closed circle) Cp, aR-helix, (open square) C=0, aR-helix, (open triangle) C=0, WL-helix (closed triangle) C, /3-sheet and (open circle) C=0, 8-sheet.

Fig. 22.8. Plots of the observed chemical shift tensor components for (a) 6u (b) 822, and (c) 533for the amide carbonyl carbons in the Gly (solid circle), Ala (solid square), Val (open diamond), Leu (open triangle) and Asp (open circle) residues in peptides against the Rw o-The experimental errors of 5n and 633 are indicated by error bars.

Figure 14.5. HX reveals a temperature-dependent transition in mobility, (a) Arrhenius plot for the oxidation of protonated (circles) or deuterated (squares) benzyl alcohol by htADH. The discontinuity at 30 °C indicates a transition in activation energy for the reaction, (b) Weighted averaged HX rate constant ( HX(wA)) fot peptides from htADH plotted versus 1 /T show/s discontinuities at 30 °C in five peptides. The w/eighted averaged kHX is defined as (A(ti + 6(t2 + Ck )/NH where NH is the total number of amide hydrogens in the peptide, and A, B, and C are the number of amide hydrogens exchanging with rate...

---