Immobilization and characterization of G51 keratinolytic enzymes with potential for wool processing

IGLESIAS M; SEQUEIROS C; ISLAN GA; CASTRO GR; OLIVERA NL

Paraná

Congreso; LIV Congreso Anual de la SAIB (Sociedad Argentina de Investigación Bioquímica y Biología Molecular); 2018

SAIB (Sociedad Argentina de Investigación Bioquímica y Biología Molecular)

Bacillussp. G51 produces extracellular keratinases with potentialfor shrink-proofing of wool. Keratinases are proteases with autolytic activitywhich are restringing their industrial application in free form. Immobilizationcould contribute to a better control of their catalytic activity. Our aim wasto immobilize and characterizeG51 extracellular enzymes by cross-linking of enzyme aggregates (CLEA).G51 culture supernatant wasused for CLEA with glutaraldehyde as cross-linking agent. G51 enzyme units (EU)/glutaraldehyderatio was optimized, obtaining the best recovery of the proteolytic activitywith the lowest ratio tested (8.4% with 3.5 EU/mlglu25%). CLEA-G51thermal stability was higher (91 and 71% of residual activity after 1 h at 50and 60°C,respectively) than that of free enzymes (40 and 5% residual activity under thesame conditions). After 4 month-storage at room temperature, the free andimmobilized enzymes kept 20 and 80% of residual proteolytic activity, respectively.This improvement of storage stability suggests that immobilization couldprevent G51-keratinase autolysis and loss of activity. More than 60% of theproteolytic activity was preserved in the 3rd use, and it gradually diminishedto 30% after seven re-uses. CLEA-G51 enzymes retained its wool keratinolyticactivity (0.06 EU/ml), which is essential for wool shrink-proofing. CLEA-G51operational and storage advantages could be valuable for industrialapplications. Particularly, increased molecular size of immobilized G51 keratinasescould avoid their diffusion into the wool fiber, allowing wool treatments with higherenzyme concentrations and without excessive degradation.