Acetylcholinesterase

Silman, Israel; Dudai, Yadin

doi:10.1007/978-1-4613-4458-2_6

Cited by 7 publications

(4 citation statements)

References 192 publications

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“…Gel slicing analyses of [32P]iPr2PF-labeled 18S plus 14S enzyme run on sodium dodecyl sulfate gels without disulfide reduction indicate that about 50% of this catalytic site label occurs in the catalytic subunit dimer band while the remaining 50% occurs in the higher molecular weight bands (P. Barnett and T. L. Rosenberry, unpublished observations). Our observations are similar to those recently reported for nonreduced [32P]iPr2PF-labeled 18S plus 14S enzyme (Silman and Dudai, 1975) except that we see virtually no subunit monomer band. Thus, one-half of the catalytic subunits appears linked as subunit dimers while the remaining half is covalently associated with putative tail subunits.…”

Section: Discussionsupporting

confidence: 92%

Structure of 18S and 14S acetylcholinesterase. Identification of collagen-like subunits that are linked by disulfide bonds to catalytic subunits

Rosenberry¹,

Richardson²

1977

Biochemistry

203

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The 14S and 18S acetylcholinesterase (EC 3.1.1.7) forms present in 1.0 M ionic strength extracts of fresh electric organ of the eel Electrophorus electricus were purified by affinity chromatography. The purification procedure involved a highly efficient acridinium resin whose synthesis and use are introduced. Previous electron microscopy studies have determined that the 14S and 18S acetylcholinesterase species as well as an 8S species not observed in this study contain a 40-nm tail structure associated with discrete numbers of presumably catalytic subunits, and other reports have established that either trypsin or collagenase will convert the 8S, 14S, and 18S forms to 1 IS catalytic subunit tetramers which appear devoid of the tail structure. A comparative analysis of polypeptides present in 18S plus 14S preparations and 1 IS preparations by polyacrylamide gel electrophoresis in sodium dodecyl sulfate is presented in this report. Prior to disulfide reduction the predominant 1 IS component in sodium dodecyl sulfate was an apparent catalytic subunit dimer possessing an intersubunit disulfide bond; in contrast, only half the 18S plus 14S components corresponded to this dimer while the remainder were found primarily as two oligomers, A and B, of high molecular weight (>300 000). Exposure of either 1 IS or 18S plus 14S preparations to disulfide reduction in the absence of a denaturant selectively reduced interpolypeptide bonds and generated primarily 75 000 molecular weight catalytic subunit monomers which appeared identical in the two preparations.^Acetylcholinesterase (EC 3.1.1.7) from the electric organs of electric fish can be extracted in several molecular species.These species are characterized by various sedimentation coefficients. From the eel Electrophorus electricus, 8S, 14S, and 18S forms have been purified and examined by electron microscopy (Rieger et Dudai et al., 1973). All three forms are highly asymmetric oligomers and appear as clusters of, respectively, 4, 6-8, and 10 or more subunits attached to an elongated tail. Species of 8, 14, and 16 Shave been purified from extracts of Torpedo californica (Lwebuga-Mukasa et al., 1976). These enzyme forms from either fish can be converted to 1 IS species by treatment with trypsin or by an apparent autolysis on storage of crude enzyme solutions (Massoulie and Rieger, 1969). Electron micrographs of purified 1 IS enzyme from eel show globular structures of four subunits without the tail. Other properties of these enzyme glycoprotein f From the

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Section: Discussionsupporting

confidence: 92%

Structure of 18S and 14S acetylcholinesterase. Identification of collagen-like subunits that are linked by disulfide bonds to catalytic subunits

Rosenberry¹,

Richardson²

1977

Biochemistry

203

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“…The splitting of the 'minimal catalytically active subunit' into two main parts under the conditions of sodium dodecylsulfate denaturation and 2-mercaptoethanol or dithiothreitol reduction have been demonstrated by several authors while active-site serine (labelled with diisopropylfluorophosphate) has been found to be included in the 60000-M, fragment [8,29,30,37,42].…”

Section: Discussionmentioning

confidence: 99%

Cobra Venom Acetylcholinesterase

Raba¹,

Aaviksaar²,

Raba³

et al. 1979

European Journal of Biochemistry

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Acetylcholinesterase from cobra (Naja naja oxiana) venom has been purified by affinity chromatography to an homogeneous state, as ascertained by sodium dodecylsulfate/polyacrylamide gel electrophoresis and sedimentation analysis. The specific activity of the preparation was 5000 IU/mg with acetylcholine as substrate. Unlike acetylcholinesterases from insoluble cell structures, the native molecule of the cobra venom enzyme consists of a single polypeptide chain of molecular weight 67000 ± 2000. At high enzyme concentrations (> 0.2 mg/ml, > 1 μM) and ionic strength 0.1 M, it reversibly tends to form higher‐molecular‐weight 7.1‐S aggregates. Despite the apparent structural simplicity of the venom acetylcholinesterase, the disc electrophoresis and isoelectric focusing experiments revealed that the enzyme exists in a number of forms with a common molecular weight but with different isoelectric points. Neuraminidase treatment did not reduce the number of the forms.

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“…Catalysis by AcChoEase has been relatively well characterized for the trypsin-solubilized membrane-free enzyme from electroplax tissue (3). Recently, work has begun to focus on the membrane-bound enzyme (4,5). Steady-state kinetic information shows little functional difference between the two enzyme preparations (6,7).…”

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confidence: 99%