A simplified and improved method of preparation of acetylcholinesterase of the eel's electric organ

Hargreaves, Alberto B.; Wanderley, Adilson Barros; Hargreaves, F; Gonçalves, Heloisa S.

doi:10.1016/0006-3002(63)91874-2

Cited by 6 publications

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“…A chromatographic procedure for the purification of the enzyme (Hargreaves et al, 1963) has been utilized to obtain a preparation having a specific activity of 40; this preparation on ultracentrifugation gave s2o,u values of 4, 6.05, and 14 S, which might correspond to molecular weights of approximately 70,000, 100,000, and 300,000.…”

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confidence: 99%

A Partial Characterization of Acetylcholinesterase^*

Kremzner¹,

Wilson²

1964

Biochemistry

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The enzyme acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) has an important role in nerve functions. The enzyme was prepared from the electric tissue of the Electrophorus electricus, using column-chromatographic procedures. This preparation, the most active yet de-scribed, is nearly chromato graphically pure and has a specific activity of 660 mmoles acetylcholine hydrolyzed /hour per mg of protein. The molecular weight was determined to be approximately 230,000, based on a sedimentation coefficient of 10.8 X 10-13 and a diffusion coefficient of 4.3 X 10 ~7 cm2/sec. On the basis of equivalent weight determinations the sedimenting species of the enzyme contains four active sites. By the methods used, sedimentation, diffusion, and gel filtration, no evidence was found for the existence of a substantially higheror lower-molecular-weight species of the enzyme. In gel-filtration studies with an agar column the enzyme moved with catalase, suggesting a molecular weight of about 250,000. The friction ratio was calculated to be 1.25, which is indicative of a globular protein.

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confidence: 99%

A Partial Characterization of Acetylcholinesterase^*

Kremzner¹,

Wilson²

1964

Biochemistry

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“…Our results demonstrate that the method of preparation has a significant effect on the physico-chemical properties of acetylcholinesterase. This phenomena undoubtedly accounts for the widespread variation in reported molecular weights of the native enzyme [l-5,7, 24,30,33]. Furthermore, the response of variously prepared "monomer" to different solvent conditions can vary widely (see Fig.…”

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confidence: 99%

Acetylcholinesterase Interaction with a Lipoprotein Matrix

Grafius

Bond

Millar

1971

European Journal of Biochemistry

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The nature of the components and some of the association forces in aggregated acetylcholinesterase, extracted from the electric organ of Electrophorus electricus, were mvestigated. The aggregated acetylcholinesterase (rapidly sedimenting, 70 S, and referred to as fast acetylcholinesterase) and the dissociated or "monomer" acetylcholinesterase (11.5 S and referred to as slow acetylcholinesterase) were isolated by zonal centrifugation. The fast acetylcholinesterase was further processed by gel filtration, resulting in a fast acetylcholinesterase of low specific activity and a slow acetylcholinesterase of high specific activity and a lowered sedimentation value (10.8 S). The fast acetylcholinesterase was exposed to the hydrolytic action of various enzymes (neuraminidase, hyaluronidase, alkaline phosphatase, and phospholipase A) and examined by sucrose gradient centrifugation techniques with no effect observed on the aggregation. However, phospholipases C and D and pancreatic lipase dissociated the fast acetylcholinesterase to the slow acetylcholinesterase (1 1.5 S). With phospholipase C, but not pancreatic lipase, the acetylcholinesterase was released from a matrix of ultraviolet absorbing, non-enzymatic material which remained in its aggregated form. With pancreatic lipase the matrix was also dissociated into a "monomer" species with a sedimentation value similar to that of the "monomer" acetylcholinesterase (resembling dissociation in high ionic strength). The hydrolytic action of the lipases did not alterthe sedimentation value of the "monomer)' nor its property of reversibly forming a gelatinous precipitate at pH 4.0. However, the slow acetylcholinesterase recovered from the gel column was not sensitive to the acid pH. The results indicate that the aggregated or fast acetylcholinesterase is a complex between ('monomer" and a matrix of lipoproteins which, in itself, is an aggregation of molecular species similar in sedimentation value to the "monomer" acetylcholinesterase. A model is presented. Comparison between the matrix and the receptor protein is made.

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Thermal properties of tetraalkoxysilanes

Alagar

Krishnasamy

1986

J of Chemical Tech & Biotech

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Tetraalkoxysilanes were prepared by reacting SiCl4 with alcohols in the liquid phase in the presence of pyridine. Based on the experimental evidence and theoretical calculations, tentative structures have been proposed. Thermal conductivity measurements for these samples were done over a temperature range 303–463 K and the data are compared with the theoretical values derived from empirical equations. In addition, other properties such as specific heat (Cp), thermal expansion (α) and oxidation stability were determined and the values are compared with the reported values for polymethy Isiloxanes.

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A simplified and improved method of preparation of acetylcholinesterase of the eel's electric organ

Cited by 6 publications

References 0 publications

A Partial Characterization of Acetylcholinesterase^*

A Partial Characterization of Acetylcholinesterase^*

Acetylcholinesterase Interaction with a Lipoprotein Matrix

Thermal properties of tetraalkoxysilanes

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A simplified and improved method of preparation of acetylcholinesterase of the eel's electric organ

Cited by 6 publications

References 0 publications

A Partial Characterization of Acetylcholinesterase*

A Partial Characterization of Acetylcholinesterase*

Acetylcholinesterase Interaction with a Lipoprotein Matrix

Thermal properties of tetraalkoxysilanes

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Product

Resources

About

A Partial Characterization of Acetylcholinesterase^*

A Partial Characterization of Acetylcholinesterase^*