Date of Award:

5-1-1967

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Zoology

Committee Chair(s)

John R. Simmons

Committee

John R. Simmons

Abstract

A system, reported by Morrison (1964), for the in vitro synthesis of Drosophila tryptophan pyrrolase has been critically studied. This putative system is based on the addition of a Drosophila "RNA" extract to a Drosophila cell-free protein synthesizing system; the synthesized enzyme is then allowed to catalyze a specific reaction, the product of which is measured by direct adsorption.

The results of this study present a three-fold argument against the interpretation of synthesis of tryptophan pyrrolase in the Morrison in vitro system: (1) RNA from a null-allele, v36f, stimulated the same tryptophan pyrrolase "activity" in the in vitro system as Canton-s RNA. (2) The Bratton-Marshall test, a valid kynurenine assay in this system, detects no tryptophan pyrrolase activity in systems showing "activity" when assayed by the direct adsorption method used by Morrison. (3) An ascorbate dependent, nonenzymatic reaction, which produced a pseudotryptophan pyrrolase activity, was detected in the Morrison assay system. This pseudoactivity, which is eliminated by the substitution of 2-mercaptoethanol for ascorbate, was interpreted by Morrison as being representative of tryptophan pyrrolase produced in the in vitro system.

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