Exploring the limits of DNA

Feb 10, 2002, Vol . 23, No. 3
By Carol Thorbes

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Dipankar Sen's eyes scan the ladder-like strands of information in a three-dimensional model of deoxyribonucleic acid (DNA), the genetic alphabet of higher organisms.

"I have no desire to play God," says the Simon Fraser University biochemist. "I just want to explore the outer limits of what DNA can do. That includes conceptualizing and testing what DNA may contribute to such diverse fields as the study of enzymes and electronics at an atomic level."

Sen is exploring the potential for designer DNA to function as enzymes - vital biological compounds that instigate chemical changes and cellular processes in organisms.

Sen's research could eventually help doctors hunt down and destroy killer viruses and rehabilitate mutated cells on demand.

DNA, as it occurs within living cells is little more than a repository of genetic information. It's not good for much else because of its chemical inertia.

However, similar to a few other scientists whose work parallels his, Sen has discovered in the last 10 years that enzymes can be constructed from DNA molecules.

He has also found that synthetic DNA enzymes can function as efficiently as naturally occurring enzymes made from ribonucleic acid (RNA), the more catalytic cousin of DNA.

Originally from Calcutta, India, Sen is one of a handful of biochemists worldwide investigating the potentially curative powers of designer DNA enzymes.

"They are still cruder than naturally occurring protein enzymes," says Sen, whose research recently earned him a Michael Smith Foundation for Health Research (MSFHR) award. "But they can be selected from huge random-sequence, synthetic DNA libraries, which affords us endless opportunities to create enzymes that perform very specific therapeutic functions."

The opportunities, says Sen, exceed those available through protein engineering, a more prevalent technology that shuffles amino acids to construct synthetic proteins.

Sen's fascination with the design potential of nature's ladder of life has also taken him down another research road less travelled.

The doctoral graduate of Yale University, who has worked with Nobel prize winning biochemist Walter Gilbert, is examining how to harness the electrical conductivity of the DNA double helix in nanotechnology. It deals with the manufacture and manipulation of products at an atomic level.

Sen envisions DNA as an electrical tool that can be used to create tiny electronic circuits, minute molecular switches and a new kind of gene chip.

Through it electrically charged, DNA-based sensors could potentially round up and manipulate enzymes, metabolites, drugs, proteins and other molecules.

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