Prevention of protein aggregation by extracellular fungal sucrase of Termitomyces clypeatus

Abstract

Abstract Objective Extracellular sucrase from Termitomyces clypeatus is known to impart stability and enhance activity of cellobiase, another secreted glycosidase of the fungus through co-aggregation with cellobiase. To explore whether sucrase can bind with some proteins like Insulin, BSA, alcohol dehydrogenase (ADH), carbonic anhydrase and whey proteins and prevent their dithiothreitol (DTT) induced/thermal aggregation and/or loss of activity measuring by spectrophotometry, gel filtration assay and activity assays. Methods MALDI-TOF and dynamic light scattering were used to assess the monomeric and aggregated molecular size of sucrase. Thermostatted spectrophotometric assays, gel filtration assays were used to study protein aggregation. Fluorescence of bound ANS was used to monitor temperature induced structural changes in sucrase together with determination of melting temperature. Results The mass of the monomeric unit of sucrase as 6649 Da. Enzyme inhibited DTT induced aggregation of insulin and suppressed the thermal aggregation of carbonic anhydrase, ADH and whey proteins, respectively by 83%, 68% and 70% at 70°C. Sucrase also protected about 84% activity of ADH. Conclusion An extracellular fungal sucrase with a low monomeric size can efficiently prevent protein aggregation. The studies can impart knowledge about potential therapeutic applications of this industrially important enzyme in protein misfolding disorders.