Low molecular weight chitosan is an efficient inhibitor of ribonucleases

RNase inhibitors are commonly used to block the RNase activity in manipulations with RNA-containing preparations. Recently RNase inhibitors, either synthetic or natural, have been intensively sought because they appeared to be promising for therapy of cancer and allergy. However, there is only a limited number of efficient RNase inhibitors. We have shown that a low molecular weight chitosan (Mr ∼ 6 kDa) inhibits activity of pancreatic RNase A and some bacterial RNases with inhibition constants in the range of 30–220 nM at pH 7.0 and ionic strength 0.14 M. The preferential contribution to the chitosan complex formation with RNases is due to establishment of 5–6 ion pairs. The results of this work show that polycations may efficiently inhibit ribonuclease activities.