Question

Although unsubstituted D -ribose is most stable as the β -pyranose, its structure in nucleotides is the β -furanose form. Why might the B-D- ribofuranose isomer be selected over the most abundant isomer? Structually, what are the arguements as to why this would this happen?

Answer 1

1. Ribose was selected as the sugar component of nucleic acid or nucleotides( based on choice).

this was best to fit by using molecular modeling andconfoguration.

2. Ribose In RNA and DNA contained 5 membered furanoside and deoxy ribose (furanoside) forms.

3. The tetrahydrofuran occrs in various natural components/;nucleic acid, carbohydrates in biology.

4. In carbohydrates chemistry in biology, various carbohydrates present as pyranose form but in case of nucleic acid, they appeared as a furanose form.

5. In furanose form of ribose and deoxy ribose, it very stable in this conformation and easy to measure their molecular modeling of complicated molecules and we can better understand chemical reactions and physical importance.

The structure is based on solid phase NMR, X-ray diffraction tech and neutran diffraction studies.

In Beta- D anomer, anomeric H placed down at 1-position in Haworth structure, it is more stable and when base react at thisposotion from up position of -OH, therefore beta form is more stabilized in Nucleic acid than alpha and beta proton in NMR more deshield.