Dr Michael Creeth
Harding, Steve, The Independent (London, England)
Scientist who helped pave the way for Watson and Crick
Michael Creeth had a long and distinguished scientific career and made a significant contribution to one of the greatest scientific discoveries of the last century, when as a young PhD student his experiments confirmed the existence of the special bonds known as hydrogen bonds which hold the two strands of the DNA molecule together. This finding, based on measurements of the viscosity of highly purified solutions of DNA, was published in 1947 and proved crucial for the Nobel Prize-winning discovery of the double helix six years later by James Watson and Francis Crick.
Creeth was born in Northampton in 1924 and went to the local Northampton Town and County Grammar school. He stayed in the East Midlands to read Chemistry at what was then University College, Nottingham, and after graduation commenced a PhD under the supervision of D.O. "Doj" Jordan and J.M. Gulland. Working on a highly purified DNA sample from calf thymus, a carefully performed series of measurements clearly showed the hydrogen bond link between the residues, a finding which was reported in the Journal of the Chemical Society in 1947.
In his PhD thesis - which also appeared in 1947 - he proposed a model for the assembly of the DNA molecule, with a phosphate-sugar backbone and the sugar-linked bases available for pairing. The model has two strands each made up of overlapping short chains linked by inter-chain hydrogen bonds built up into a very long and elongated molecule leading to a high relative viscosity.
At extremes of pH the hydrogen bonds are disrupted and the two- chain structure falls apart, leading to a large reduction in viscosity. Apart from the breaks in the chains - and the absence of a helix - the model is not too far removed from what was discovered in 1953 by Watson and Crick. They acknowledged how important a step the discovery of the Nottingham team was for their ultimate evaluation of the structure of DNA. …