In this article we will discuss about the X-ray crystallographic studies of DNA. In 1920, the basic chemical composition of nucleic acid was elucidated through the efforts of P.A. Levene. In 1940, for the first time W.T. Astbury gave first three dimensional structure of DNA model studied through X-ray crystallography. He concluded that its flat nucleotides get stacked to form [...]
The most common form of DNA which has right handed helix and proposed by Watson and Crick is called B-form of DNA or B-DNA. In addition, the DNA may be able to exist in other forms of double helical structure. These are A and C forms of double helix which vary from B- form in spacing between nucleotides and number [...]
In this article we will discuss about the Watson and Crick’s Model of Double Helix of DNA. Watson and Crick studied in advance the manuscript of Pauling and Corey in 1953. They concluded that: (i) Polynucleotide chain of DNA has a regular helix, (ii) The helix has a diameter of about 20 Å, and (iii) The helix makes a full [...]