Properties of carrageenan gels with immobilized lysozyme

Absract  Rheological properties of 3% carrageenan gels formed in 0.4 M sodium chloride solution in the presence of lysozyme are studied in detail. It is shown that the addition of protein results in an increase in the gel-sol transition temperature by 2°C (transition temperature of 3% gel is 48°C, lysozyme concentration is 0.5 mg/ml). Based on the frequency dependences of dynamic moduli at various temperatures, it is revealed that systems possess viscoelastic properties at low frequencies. Within a wide frequency range up to gel-sol transition temperature, systems become elastoviscous and, at higher frequencies, they demonstrate forced transition to glassy state. It is shown that carrageenan inhibits enzyme activity of lysozyme. The interaction between enzyme and carrageenan leads to changes in lysozyme conformations, i.e., the content of α-helices increases and that of turns decreases. It is demonstrated for the first time that, in the presence of a so-called nonspecific (for the gelation of carrageenan) sodium ion, it is possible to prepare gels with the necessary structure and rheological properties and gel-sol transition temperature. These gels can release a lysozyme under the conditions of transmucosal prolonged delivery. Original Russian Text ? G.P. Yampol’skaya, A.A. Elenskii, N.V. Pan’kina, B.N. Tarasevich, V.G. Kulichikhin, 2009, published in Kolloidnyi Zhurnal, 2009, Vol. 71, No. 2, pp. 275–284.