Flat Ladder DNA model

Jong Bhak and Jamie Keddie.

Flat Ladder DNA (FLD) is a DNA structure model proposed by Jong Bhak and Jamie Keddie in 1992.

The main idea of FLD model is that the cannoncal structure of DNA is not double helix but a flat DNA. FLD model regards double helix model one of many conformations DNA can have.

This model was conceived from 1) involving topoisomerase for DNA supercoil and helix structure is too complicated to explain DNA functions 2) there are circular genomes and if the DNA is coiled helices, it would be too complicated to wind and unwind DNA strings.