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The Evolutionary Jump from Single to Double-stranded DNA

Clive Delmonte clivedelmonte at c-i-delmonte.freeserve.co.uk
Mon Jul 12 18:28:21 EST 1999

One of the many interesting aspects of the proposed Watson-Crick
double-helical DNA structure when it was published in 1953 was the implied
need for organisms to have evolved, perhaps suddenly, the many genes coding
for the many proteins which would be needed to execute the all functions of
the plectonemically wound two-stranded DNA in the cellular, and, indeed the
organisms' life cycle.

The equivalent operations in an organism based upon single-stranded DNA
would seem to be far simpler (if more vulnerable to damage).

However, Watson & Crick had overlooked a double-stranded, base pairing
structural possibility which did not involve plectonemic winding, and this
structure was caught in great detail by scanning tunnelling microscopy by
Lee et al. (SCIENCE vol 244 (1989) 475-477 (Figures 3b and 3d)), as
subscribers may know.

The structure found by Lee et al. does not seem to need any new proteins,
since it consists of a true side-by-side duplex where, in a relaxed state,
there is zero plectonemic winding over any and all lengths.  Single strands
of DNA, as long as they are complementary in sequence, will form a duplex by
approaching each other in a linear fashion, and they will separate

This structure, and its implications, have been the subject of three books
(one in press), the first of which has attracted several comments:

1        Towards A New Structural Molecular Biology, by Clive Delmonte
(1991) ISBN 0 9512276 0 2

"...I find much of Delmonte's critique of other workers sound enough to
raise doubt in my mind about the bulk of classical work in this area.  There
is an inordinate amount of the use of models in solving structures ... and
there is (as a result ) remarkably little that is known solidly... In this
respect, the book was an eye-opener."

Prof. Steven Benner at Eidgenossische Technische Hochschule, Zurich, and

"...the widely accepted Watson-Crick model is inadequate to explain many
important pieces of data, and in some cases defies intuitive biological and
physical logic as a predictive model...I commend you on your recognition of
inconsistencies in the story of DNA...you have the potential of changing
molecular biology."

Prof. Robert Hopkins at University of Houston at Clear Lake, Texas
2        Advances in AFM & STM Applied to the Nucleic Acids, by Clive
Delmonte (1997) ISBN 0 9512276 2 9
3        DNA Structure Puzzles, by Clive Delmonte (1999)  (ISBN applied for)

The books now have Library of Congress numbers.

To any interested subscribers, I offer copies of some of the recently
assembled DNA Structure Puzzles so that the limitations of the Watson-Crick
model can be more readily appreciated.

Clive Delmonte
E-mail: clivedelmonte at c-i-delmonte.freeserve.co.uk

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