Job plot

FIGURE 1.16 Job plot for the complexes of 0-9-fert-butylcarbamoyl-6 -neopentoxy-cinchonidine selector and DNB-Leu enantiomers. Symbols /J-enantiomer ( ), 5-enantiomer (O)- The shifts of the most diagnostic H9 proton was monitored as function of increasing molar fractions X of DNB -Leu enantiomers and the total concentrations were 10 mM in methanol-rir. (Reproduced from N.M. Maier et al., J. Am. Chem. Soc., 124 8611 (2002). With permission.)... 

The equilibrium dialysis experiment revealed that histidine-substituted salicylamide was selected as an RNA ligand. Subsequent binding analysis by UV titrations and Job plot revealed the histidine-substituted salicylamide Cu + complex bound the target RNA hairpin with an apparent dissociation constant of 150 nM. This binding constant likely reflects more complex binding processes than a simple 1 1 interaction, as the observed binding curve saturates well below the concentration of the histidine-substituted salicylamide, and thus the actual affinity of the complex for targeted RNA is probably lower. Importantly, however, titrations with the... 

Job plots have established the stoichiometry of several iron(III)-3-hydroxy-2-methyl-4(l//)-pyridinone systems in aqueous solution.Stability constants have been determined for 1,2-dimethyl-, 1,2-diethyl-, and several other 3-hydroxy-4-pyridinonato-iron(III) complexes. " These data supplement and update the long-standing set of log / 3 values for... 

Concentration is the most common means for describing the composition of a solution in biochemistry. Enzyme kinetic expressions are typically expressed in these concentration units. Unless otherwise noted, this is the method used throughout this text. Nevertheless, other methods for describing compositions are utilized. For example, mole fractions are often used in Job plots. Gases in solution are commonly measured in terms of partial pressures. Below is a brief description of a few of these other conventions or methods. 

NUCLEATION COOPERATIVITY ALLOSTERISM HYSTERESIS JENKINS MECHANISM JOB PLOT... 

COMPUTER ALGORITHMS SOFTWARE JOB PLOT Johnson noise,... 

Figure 19-8 Ideal behavior of Job plots for formation of the complexes P3X, PX, and PX2.

Fig. 5 UV/Vis titration of 45a with Bu4N+C1 in CH2C12. The arrows show changes due to increasing concentration of Cl". Inset Job plot...

Very recently the first anion receptors 49 based on thiacalixarene units were reported [60] and their complexation abilities towards Cl anion were studied by XH NMR titrations in CDC13. The Job plot analysis clearly confirmed the formation of the 1 1 complexes, whilst the corresponding complexation constants depend on the length of alkylene chains on the lower rim. The lower the rigidity of the system (the longer chain), the weaker is the binding (compare Kc for 49a (3,480 M"1), 49b (1,900 M"1), 49c (1,790 M"1)). The comparison of 49a and 49d shows that the thioureido derivative is a slightly worse chloride receptor... 

A tetraamidinium functionalized, bowl-type cavitand (receptor 8) was developed by Diederich and Sebo [47]. This receptor was found to complex 1,3-dicarboxylate anions with good selectivity and a 1 2 binding stoichiometry both in CD3OD and D20, as revealed by standard Job plot analysis. In contrast, various nucleotide phosphates were found to be bound with a 1 1 stoichiometry in D20. In the case of the adenosine phosphates, the association constants increased as a function of nucleotide charge [i.e., the affinity order (K., M-1) was cAMP (1400) < AMP (10000)charged receptor (8) also showed moderate selectivity towards AMP (Ka = 10 000 M-1) over other nucleotide monophosphate anions, such as GMP (FCa = 5200 M-1), CMP (fCa = 3500 M-1), TMP (K l — 5900 M ), and UMP (Ka-3800M ) in D20 containing TRIS buffer (2.5 mM, pH 8.3). 

The stereoregularity of the polymers is also important to the complex formation. The Job plots of atactic polyMAOU and three forms of stereoregular polyMAOA in DMSO-ethylene glycol (3 2 v/v) are shown in Fig. 10. The order of the interactions obtained is... 

Figure 20 shows the Job plot of the poly A/T-PEI system at pH 7.2. A decrease in absorbance was observed at a high ratio of T-PEI namely 1 9 (A T). This phenomenon resembles that of the poly A/poly VUr system. At a molar ratio of 1 2 (A T) hyperchromicity was observed (Fig. 20). Under this condition, poly A is known to form a single helix with a broad melting profile. The melting profile of the 1 9 (A T) complex is narrower than that of poly A.

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