Date of Award:

5-1-1980

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Life Sciences:Biology

Committee Chair(s)

Gene W. Miller

Committee

Gene W. Miller

Committee

Joseph C. Street

Committee

Thomas M. Farley

Committee

George W. Welkie

Abstract

The activity of two enzymes, delta-aminolevulinic acid (ALA) synthetase and 4,5-dioxovaleric acid (DOVA) transaminase, were determined in crude extracts of three strains of Rhodopseudomonas sphaeroides, (1) a wild type, (2) a mutant strain which can not form chlorophyll without the addition of ALA in the growth medium (known as H5) and (3) a second mutant strain which regained its ability to form chlorophyll without the addition of ALA in the medium (known as H5D). The results show that all three strains have DOVA transaminase activity, while ALA synthetase activity is found only in the wild type. Another experiment utilized D0VA in the growth medium of H5 or H5D, but this did not help their growth. These results indicate that DOVA is not an intermediate in the formation of chlorophyll in the H5D mutant strain, although the uptake of DOVA by the cell was not determined in this study. The mutant strain that is not able to form bacteriochlorophyll without the addition of ALA in the growth medium (H5) also has DOVA transaminase activity in crude extracts. This raises the possibility that a different pathway other than that catalyzed by ALA synthetase or DOVA transaminase is used in the formation of ALA by the mutant strain H5D. The locations of the two enzymes have been studied from different fraction preparations (periplasm, cytoplasm and membrane). Hydroxymethyl aminomethane (Tris) and ATP inhibition of DOVA transaminase has also been investigated.

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