The Quaternary Structure of Chicken Acetylcholinesterase and Butyrylcholinesterase; Effect of Collagenase and Trypsin

Abstract

Acetylcholinesterase (EC 3.1.1.7.; AChE) and butyrylcholinesterase (EC 3.1.1.8.; BuChE) from chicken muscle exist as sets of structurally homologous forms with very similar properties. The collagenase sensitivity and aggregation properties of the 'heavy' forms of both enzymes indicate that they possess a collagen-like tail, and their stepwise dissociation by trypsin confirms that they correspond to triple (A12) and double (A8) collagen-tailed tetramers. In addition to this dissociating effect, trypsin digests an important fraction of the catalytic units of AChE, in a progressive manner, removing as much as 30% of the enzyme's mass, without inactivation of the tetramers and of the tailed molecules. The trypsin-modified AChE forms closely resemble the corresponding mammalian AChE forms in their hydrodynamic properties. It is not known whether the trypsin-digestible peptides, which do not appear to be involved in the ionic or hydrophobic interactions of the enzymes, are a fragment of the catalytic subunit or whether they constitute distinct polypeptides.

Molecular forms of acetylcholinesterase and pseudocholinesterase in chicken skeletal muscles : their distribution and change with muscular dystrophy

“…On treatment with collagenase, we find that a transformation occurs similar to that found with eel symmetric form and then a detachment of some subunits. Hence, the chicken muscle 20 S AChE is also a collagen-tailed structure ; this conclusion is supported for both the 20 S and the 15 S forms by the results of partial tryptic digestion (Allemand et al, 1981 (Lyles et al, 19811. Changes of molecular forms with embryonic development. -In the embryonic pectoral muscle, L 2 is the major at day 14, but M and H 2c are prominent ( fig.…”

Hierarchy of Post-translational Modifications Involved in the Circulatory Longevity of Glycoproteins

“…Dimers further assemble into stable quaternary complexes that represent the main form of circulatory acetylcholinesterase, as is the case of serum-derived fetal bovine AChE. In several occasions monomeric subunits of AChE have been reported (59,61), but their origin as breakdown products of multimeric forms could not be ruled out (62)(63)(64)(65). The nonphysiological dimeric and monomeric configurations of cell culture-generated AChE has been reported to characterize other versions of recombinant cholinesterases as well.…”

A conformation‐dependent monoclonal antibody against active chicken acetylcholinesterase

“…A mild trypsin digestion modifies the sedimentation coefficients of all molecular forms of chicken AChE, probably by removing a peptidic region which is not involved in their catalytic activity or in their quaternary organization [15]. We characterized the binding of C-13 1 and other antibodies to intact and trypsin-modified forms of AChE, by analysing the capacity of the antibodies to shift their sedimentation in sucrose gradients.…”