Multiple Molecular Forms of Cholinesterase from Elongated Animals

Author: Johnson, Carl Douglas

Year: 1977

Degree: Dissertation (Ph.D.)

Advisor: Russell, Richard L.

Committee Member: Unknown, Unknown

Option: Biology

DOI: 10.7907/x6s3-4159

Abstract

Cholinesterase activity in Electrophorus electricus and Caenorhabditis elegans has been fractionated, primarily by velocity sedimentation in sucrose gradients. The electric organs of E. electricus contained five separable forms (7,5 S, 9 S, 12 S, 14 Sand 18 S). Three, so-called native forms (9 S, 14 Sand 18 S) are insoluble in low-ionic strength solutions and they were all shifted to higher sedimentation constants by treatment with bacterial collagenase. The other two (globular) forms are soluble in low-ionic strength solutions and unaffected by collagenase. Trypsin converts the native forms to the 12 S form. Neither collagenase nor trypsin affect the molecular size of the active subunit as determined by SDS-polyacrylamide gel electrophoresis.

Four forms of cholinesterase activity were separated from extracts of the soil nematode Caenorhabditis elegans (5 S, 7 S, 11 S, 13 S). The smaller two forms as a pair and the larger two forms as a second pair are kinetically similar (Kms, substrate and inhibitor specificity). There are significant differences between the pairs. A screening procedure using the selective inactivation of the 5 Sand 7 S forms by the anionic detergent sodium deoxycholate has been applied to 89 mutants of C. elegans. One uncoordinated mutant (BC46) apparently devoid of 11 S or 13 S activity was identified. The 5 S and 7 S forms in this mutant are unaltered. The behavioral defect is limited to the body region. Head movements and sensory responses to mechanical, chemical and osmotic stimuli seem unaltered. The mutation is X-linked.

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