# MULTIENZYME COMPLEX FOR DNA SYNTHESIS IN MAMMALIAN CELLS

> **NIH NIH R01** · UNIVERSITY OF VIRGINIA · 1987 · $121,839

## Abstract

Deoxyribonucleic acid (DNA) possesses an innate ability to duplicate
precisely.  While this duplication does not require intervention of
additional overriding sources of specific information, the enzymological
mechanism by which it is accomplished is still not clear.  Besides the
mechanism of DNA replication, the control of this process, especially as
related to other macromolecular synthesis and cell growth, is still poorly
understood.  Extension of the proposed studies should clarify these
questions.  In general, the knowledge gained through these studies can be
used in developing new and effective strategies for cancer chemotherapy.

Physical and functional interaction between the enzymes of DNA biosynthesis
in mammalian cells was suggested from the observations that; a) Enzymes of
DNA biosynthesis, only from the nuclei of S phase cells, co-sediment in a
sucrose density gradient as a high molecular weight entity.  By contrast,
in G0 and G1 phase cells the enzymes were in the cytoplasm in a soluble
form; b) Ribonucleoside diphosphates incorporated very efficiently into DNA
or 'permeabilized' S phase, but not G1 phase, cells and c) Catalytic
activity of thymidylate synthase, as measured in vivo, was critically
dependent on the phase of the cell cycle and its allosteric interactions
with ribonucleotide reductase, DNA polymerase-Alpha and topiosomerase.

In the proposed research this multienzyme complex will be investigated
further at three levels:  a) Examination of the structural and functional
role of DNA topoisomerase II in the assembly and maintenance of the
multienzyme complex; b) Evaluation of the dynamics of enzyme associations
in the presence of antineoplastic drugs, by measuring in vivo thymidylate
synthase activity and deoxynucleotide pool analysis; c) Characterization of
functional capabilities of the isolated complex in channeling distal
precursors.

Knowledge gained through these studies, particularly on the biological
assay of the multienzyme complex, will then form critical basis for the
purification of the complex.  An understanding of the specific composition
of the purified complex will be essential in achieving our ultimate
objective of isolating these components in a soluble form and
reconstituting the complex in vitro.

## Key facts

- **NIH application ID:** 3178433
- **Project number:** 5R01CA039445-03
- **Recipient organization:** UNIVERSITY OF VIRGINIA
- **SAM.gov UEI:** JJG6HU8PA4S5
- **Principal Investigator:** PREM-VEER G REDDY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $121,839
- **Award type:** 5
- **Project period:** 1985-09-01 → 1989-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3178433

## Citation

> US National Institutes of Health, RePORTER application 3178433, MULTIENZYME COMPLEX FOR DNA SYNTHESIS IN MAMMALIAN CELLS (5R01CA039445-03). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3178433. Licensed CC0.

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