Affinity pattern

The polysaccharide of Streptococcus pyogenes consists of rhamnose and N-acetyl glucosamine residues. Antibodies have been isolated from S. pyogenes by affinity chromatography by the technique described in an earlier section. The immune serum of S. pyogenes was provided by Dr. McCarty, Rockefeller University. The affinity pattern for the isolation of the antibodies is reproduced in Fig. (12) [45],... 

Fig. (14). Affinity pattern, agar diffusions (C and D), A=S. pneumoniae, B=S. mulans, and immunoglobulin class (Ab) of anti-S. mutans or anti-X pneumoniae antibodies (Ab), A[, G, M, globulins..

The purification was by chromatography on DEAE cellulose. Electrophoresis of the purified enzyme and the original filtrate are shown in Fig. (27) [71]. Rabbits were immunized with the pure glucoamylase [72]. Antibodies in the serum were purified by affinity chromatography. The affinity pattern for glucoamylase purification is shown in Fig. (28). Electrofocusing and assay by the coupled method for antibodies is shown in Fig. (29). The glucoamylase antibodies consist of 8 isomers [73],... 

Arylmetals can be coupled with alkenyl and alkynyl halides. In these cases, the reverse polarity affinity patterns, i.e., the alkenyl-aryl and alkynyl-aryl coupling reactions... 

It is possible in chiral CE to adjust the enantiomer migration order without changing the affinity pattern of the analyte enantiomers towards a chiral selector. This is impossible in chromatographic techniques unless using a chiral selector as a CM PA [42]. 

The reversal of the affinity pattern of enantiomers towards a chiral selector is the most dramatic change that may take place due to any chemical or structural modification of a chiral selector. The screening of the affinity pattern of a wide range of chiral analytes towards CyD-type hosts using CE indicated that the affinity pattern... 

Table 6.1. Enantiomer affinity pattern of selected chiral analytes towards native CyDs having different cavity size (Reproduced with permission from Ref. 56).

Another example when ROESY experiments may provide information about distinct differences between the structures of analyte-CyD complexes is the complex of chiral yS2-sympathomimetic agent clenbuterol (CL) with / -CyD and heptakis (2,3-di-0-acetyl)-yS-CyD (HAD-j8-CyD). Again it was noted from the CE experiments that the enantiomers of CL exhibit an opposite affinity pattern towards these two CyDs (Fig. 6.8) [60]. 

The opposite enantiomer affinity pattern of the antihistaminic drug brompheniramine (BrPh) towards j8-CyD and TM-j8-CyD provoked us to study the structure of the corresponding diastereomeric complexes in solution using ID-ROESY [61]. For the complexes of (+)-BrPh with both CyDs, unambiguous confirmation was obtained indicating the inclusion of the 4-bromophenyl moiety of the analyte in the cavity of the CyD. In addition, in the case of the (+)-BrPh complex with fS-CyD, a weak but positive NOE effect was also observed for the protons of the maleate counter anion when saturating the CyD protons H-3 and H-5 located inside the cavity. This observation may indicate the simultaneous inclusion of the 4-bromophenyl moiety and maleate counter anion in the cavity of -CyD but this contradicts simple geometric considerations and the assumption that the stoichiometry of the complex is 1 1. 

An additional point is that both mobility and affinity effects must be considered and a conclusion about a favorable affinity pattern for an enhancement of a chiral separation may be drawn depending on the effect of both chiral selectors on the mobility of the analyte [12, 47], Some of these points are illustrated in [48] using the anticoagulant drug warfarin as a chiral analyte. 

In chromatographic techniques, there is no alternative mechanism beyond the affinity reversal for a reversal of EMO. In contrast, CE offers various possibilities for a designed reversal of EMO without any change in the enantiomeric affinity pattern of the analytes toward the chiral selectors [2, 17, 18, 139-141]. 

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