Specific Ligands for the Affinity Chromatography of Cholinergic Proteins

Abstract

SummaryAffinity chromatography of proteins requires a ligand covalently bound to a solid support separated by a spacer of sufficient length. In the specific case of acetylcholinesterase we have reduced the conventional spacer synthesis from five to three steps.For affinity chromatography of cholinergic proteins the ideal ligand would be acetylcholine which, however, could not be used because it is easily hydrolyzed. We synthesized hydrolysis-resistent ligands. Different specific ligands were synthesized for the affinity chromatography of serum esterase.Affinity chromatography has achieved great importance in the last decade for the purification of biologically active proteins [l-31. In this method a ligand bound covalently to a solid support creates an affinity for the desired protein. As proteins generally have large molecular volumes, the ligand must not be too closely bound onto the support. Cuatrecasas [ 11 first mentioned the importance of a 'spacer'. In the case of acetylcholinesterase, from both theoretical and practical experience, the ligand must be bound to a spacer of 45-58 A of length to achieve optimum interaction with the active centre of the enzyme. The definition 'affinity chromatography' has been used differently by several authors. Unspecific elution of the desired protein with increasing ionic strength of buffer solutions after more or less specific adsorption on a support has also been defined as 'affinity chromatography' [4] [5]. We use the term affinity chromatography to mean specific adsorption and subsequent specific desorption chromatography.An adequate support for affinity chromatography is agarose'). Cuatrecasas [ 11 has already described in detail the spacer synthesis on agarose. Generally the following sequence leads to good results. Bromocyano-activation of agarose, coupling with a diamine, elongation with succinic anhydride, another treatment with diamine catalyzed by water-soluble carbodiimide, again elongation with succinic anhydride, and finally, carbodiimide-catalyzed coupling of the ligand.

Novel self‐disinfecting surface

“…Three compounds were prepared with dibromoalkanes of different chain lengths (4, 6, or 10 carbon atoms). A synthesis was carried out in three stages, as shown in Scheme , essentially according to the method described by Riggio et al25…”

Flexible N,N,N-chelates as supports for iron and cobalt chloride complexes; synthesis, structures, DFT calculations and ethylene oligomerisation studies

“…The preparation was carried out based on a modification of the literature report. 21 2-Chloroethylamine monohydrochloride (12.0 g, 0.103 mol) was added in portions to an icecooled solution of sodium hydroxide (51.5 cm 3 , 2 M NaOH, 0.103 mol). This was repeated and the contents of the two flasks (0.206 mol) combined.…”

Model Reactions for the Synthesis of Azacorannulenes and Related Heteroaromatic Compounds

“…Flash chromatography (silica gel; petroleum ether/diethyl ether, 1:1) provided the pure isomers, both of which have been described in the literature. [23] 16a …”

“…This compound was prepared from 16b by ether cleavage by a known method, [23] in 63% yield. 1 (10 mL).…”