Lyase-catalyzed degradation of alginate in the gelled state: Effect of gelling ions and lyase specificity

• The effect of lyase specificity and affinity of gelling ions on gel degradation was investigated.
• Lyase-catalyzed disruption of alginate gels worked well for Ca-alginate.
• Lyase activity on G–G linkages is required for effective gel disruption.
• G-blocks crosslinked with Ba2+ were protected from degradation with lyase.

Lyase-catalyzed degradation has been proposed as a more cell-friendly alternative to dissolution of alginate gels than using chelating agents. In this study, we investigated the effect of lyase specificity on degradation of alginate gels, including the effect of crosslinking ions with different affinity for the polymer. Degradation kinetics and products were analyzed. In particular, the degradation products were characterized using novel methods for alginate sequence determination by chromatography. Lyase-catalyzed gel disruption worked well for gels crosslinked with calcium, but was less effective when barium was included in the gel formulation. The importance of crosslinking of long G-blocks in maintaining the structural integrity of the gels was identified. The failure to degrade these long G-blocks, either due to protection of the G-blocks by strong ionic crosslinking or due to lack of lyase activity on G–G linkages, resulted in retained resistance to mechanical disruption of the gel.