Structure and activity transition of lysozyme on interacting with and releasing from polyelectrolyte with different hydrophobicity

Abstract

The complexes of lysozyme with poly(isobutylene‐alt‐maleic acid) (PIMA) and poly(1‐tetradecene‐alt‐maleic acid) (PTMA) at pH 7.4 were characterized using static and dynamic light scattering. The electrostatic interaction of PIMA with lysozyme results in a loose complex structure, while the electrostatic and hydrophobic interactions between PTMA and lysozyme produce a compact complex structure. Lysozyme in PIMA complex particles remains a part of activity and structure analyzed by circular dichroism and substrate hydrolysis. However, lysozyme loses its tertiary structure and activity completely in PTMA complex. NaCl is more effective to dissociate PIMA–lysozyme complex by screening the electrostatic interaction, whereas GdHCl is more effective to dissociate PTMA–lysozyme complex by forming GdHCl–PTMA precipitates through extra hydrophobic interactions. In the release process, the denatured lysozyme molecules are able to avoid hydrophobic aggregation and fully regenerate their native structure and activity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4681–4690, 2008

Sustained and Extended Release with Structural and Activity Recovery of Lysozyme from Complexes with Sodium (Sulfamate Carboxylate) Isoprene/Ethylene Oxide Block Copolymer

“…The abnormal increase in CD intensity of lysozyme in far-UV range was observed in our previous study of lysozyme and PTMA complexes. [32] The abnormal CD spectra shown in Figure 1(A) are very similar to the spectrum of lysozyme in ethylene glycol. [36] The secondary structure of lysozyme in the complexes was estimated with Model SSE-338 Protein Secondary Structure Estimation Program.…”

“…This phenomenon is similar to the complexes of PIMA/lysozyme, but is different from the complexes of PTMA/lysozyme. [32] This result suggests that the hydrophobic interactions between SCIEO and lysozyme are not very strong, so that only a partial alteration of the tertiary structure of the protein is observed. The CD result indicates that the asymmetric environment around the aromatic residues of lysozyme is partly disturbed by SCIEO.…”

“…The free lysozyme concentration was analyzed by BCA assay. The data in Table 1 show that the free lysozyme concentration was Sustained and Extended Release with Structural and Activity Recovery [32] One reason may be that some of the secondary amine groups of SCIEO are protonated at pH ¼ 7.4. [26] The electrostatic attraction between SCIEO and lysozyme exists at pH ¼ 7.4 because of the sulfonate and carboxylic groups of SCIEO and the net positive charges of lysozyme.…”

“…activity of individual lysozymes significantly. [32] Figure 2 shows that in the presence of 0.15 mol Á L À1 NaCl the relative activities of lysozyme are about 30% for all of the complex samples studied. The relative activities increase with NaCl concentration.…”

“…[32] Lysozyme in PIMA complexes retains a part of its activity and structure. However, lysozyme loses its tertiary structure and activity completely in PTMA complexes.…”