(a,b) Representative isotherms of calf thymus histone (CTH, 68.2 µM) binding to highly-sulfated HS oligosaccharides (400 µM). No binding was noted with HS tetrasaccharides (dp4, a); similarly negative isotherms were noted with dp6 and dp8 oligosaccharides. In contrast, fragments ≥ 10 saccharides (dp10, b) in size demonstrated both endothermic (downsloping) and exothermic (upsloping) binding reactions. (c) Isothermic calorimetry quantification of number of binding sites (N) and binding affinity of CTH-HS reactions.