Deoxyribonucleotide biosynthesis in green algae : characterization of thymidylate synthase-dihydrofolate reductase in Scenedesmus obliquus

Thymidylate synthase and dihydrofolate reductase are peak enzymes that accompany the S phase of the unicellular green algae, Scenedesmus obliquus, and are both overproduced in the presence of 5-fluorodeoxyuridine. Such overproducing cultures have served for enzyme isolation and characterization. It...

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Bibliographic Details
Published in:Archives of biochemistry and biophysics, Vol. 256, No. 1 (1987), p. 244-52
Main Author: Bachmann, B
Other Involved Persons: Follmann, H
Format: Article
Language:English
ISSN:1096-0384
Item Description:Date Completed 27.08.1987
Date Revised 29.06.2019
published: Print
Citation Status MEDLINE
Copyright: From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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  • Thymidylate synthase and dihydrofolate reductase are peak enzymes that accompany the S phase of the unicellular green algae, Scenedesmus obliquus, and are both overproduced in the presence of 5-fluorodeoxyuridine. Such overproducing cultures have served for enzyme isolation and characterization. It has not been possible to separate the two enzyme activities by several methods of protein fractionation, including affinity chromatography on specific immobilized ligands (fluorodeoxyuridylate or N10-formylfolate); both were enriched in parallel approximately 400-fold from algal extracts. The most highly purified samples are of low stability in solution. Enzyme activities are inhibited by methotrexate, 5-fluorodeoxyuridylate, and arabinouridylate but not by hydroxyurea; FdUMP inhibition is fully reversed after removal of the nucleotide. Sedimentation in sucrose gradients (Mr 100,000) and electrophoresis in denaturing polyacrylamide gels (Mr 50,000) suggest that the protein structure resembles more the dimeric, bifunctional thymidylate synthase-dihydrofolate reductase of protozoan species than the separate enzymes found in bacteria and animal cells