Histone H1 structural changes and its interaction with DNA in the presence of high glucose concentration in vivo and in vitro.

Histone H1 has an important role in the packing of chromatin and controlling gene expression. The effect of nonenzymatic glycation on the structure of histone H1 (a basic protein), the inhibitory role of spermine on this phenomenon and interaction of H1 with DNA is investigated here. H1 was extracted from the liver of normal and diabetic rats with or without receiving spermine as a chemical chaperone. Rat liver H1 was also incubated with glucose (50 mM) and its structure was compared with the protein obtained from diabetic rat. The results indicated a lower fluorescence emission and alpha-helical content of glycated H1; i.e., alteration in its folding; and reduced DNA (high molecular weight or specific sequences) binding in comparison with normal protein. Spermine partially (not completely) returns the studied parameters on glycated H1 toward the normal values. The changes in the structure and function of histone H1 is suggested as one of the possible mechanisms involved in diabetic complications.