Bio-physical characterization of ribose induced glycation: A mechanistic study on DNA perturbations

The non-enzymatic addition of carbonyl group of sugar moiety to the amino group of DNA macromolecule leads to the formation of early glycation products (Amadori products) which undergoes rearrangement, cyclization and dehydration to form advanced glycation end products (AGEs). While the formation of glucose derived glycated DNA has been previously demonstrated, however no extensive studies have been performed to assess the glycation of DNA using d-ribose as glycating agent. d-ribose, an important monosaccharide, is a highly reactive pentose sugar which results in the rapid formation of AGEs. To the best of our knowledge, this is the first study to characterize the d-ribose-induced changes in calf thymus DNA, as well as calf thymus DNA Amadori and calf thymus DNA-AGEs. The main objective of the study is to investigate the non-enzymatic glycation of calf thymus DNA by using different concentrations of d-ribose at increasing time period. The obtained Amadori products, AGEs were characterized with respect to the extent of DNA strand break and base modifications. Additionally, their nitroblue tetrazolium (NBT) reduction assay, absorbance, agarose gel electrophoresis, fluorescence, circular dichroism (CD) and thermal denaturation (Tm) characteristics were extensively studied. We found significant changes in the modification of DNA and in AGE-specific fluorescence, using different concentration of modifiers (d-ribose). The results provide the mechanistic insight of d-ribose induced glycation in calf thymus DNA. The bio-availability of d-ribose makes this carbonyl species quite reactive and damaging, therefore having direct implication in diabetes. This is the preliminary study done on d-ribose glycation and warrants further study to probe the role ribose-DNA glycation in different disease state including diabetes.