Enhanced Thermostability of a Fungal Alkaline Protease by Different Additives

Abstract

A fungal strain (Conidiobolus brefeldianus MTCC 5184) isolated from plant detritus secreted a high activity alkaline protease. Thermostability studies of the fungal alkaline protease (FAP) revealed that the protease is stable up to 50°C with 40% residual activity after one hour. Effect of various additives such as sugars, sugar alcohols, polyols, and salts, on the thermostability of FAP was evaluated. Among the additives tested, glycerol, mannitol, xylitol, sorbitol, and trehalose were found to be very effective in increasing the stability of FAP, which was found to be concentration dependent. Fivefold increase in residual activity of FAP was observed in the presence of trehalose (50%) and sorbitol (50%) at 50°C for 4 h, compared to FAP without additive. Other additives like calcium at 20 mM and 10–15% ammonium sulphate showed lower stability improvement than trehalose and sorbitol. NaCl, MgCl2, K2HPO4, and glycine were found to be poor stabilizers and showed only a marginal improvement. PEG 6000 did not show any increase in stability but was found to be slightly inhibitory.

A novel alkaline protease from alkaliphilic Idiomarina sp. C9-1 with potential application for eco-friendly enzymatic dehairing in the leather industry

“…We also found that the thermostability of both AprA and AprA-PPC was also significantly improved by the addition of Ca 2+ . Similar results were also observed for several alkaline proteases from organisms such as B. lehensis 16 , B. pumilus 57 , A. oryxae 81 , S. koyangensis 25 , and Conidiobolus brefeldianus 79 . Ca 2+ is considered to effect protease thermostability by strengthening the intramolecular interactions of the enzyme and by binding of Ca 2+ to autolysis sites 79 .…”

“…Ca 2+ and other divalent ions such as Mn 2+ and Mg 2+ represent additional factors known to increase protease activity and thermostability 65 , 79 . Our current study showed that both AprA and AprA-PPC were activated by Ca 2+ , Mn 2+ , and Mg 2+ .…”

“… B. subtilis WB600 pMA5 48 4935.5 102.8 B. pumilus 56 B. subtilis WB600 pSU 48 32.8 0.7 B. subtilis 65 B. subtilis DB100 pUB110 10 26.0 2.6 B. pumilus 80 B. subtilis DB430 pBSMuL2 72 5800.0 80.6 Bacillus sp. 79 B. subtilis DB104 pAH101NC 24 30.0 1.3 B. subtilis 57 B. subtilis Bios11 pUB110 11 24.5 2.2 A. oryzae 81 P. pastoris GS115 pPIC9K 120 47.5 0.4 B. stearothermophilus 12 P. pastoris GS115 pGAPZαB 72 41.3 0.6 A. nidulans 58 P. pastoris X33 pPICZαA 48 1.0 <0.1 B. cereus 82 P. pastoris X33 pPICZαA 72 122.6 1.7 A. sojae 83 P. pastoris KM71 pPIC9K 72 400.4 5.6 B. stearothermophilus 27 E. coli XL1-Blue pTrcHis 24 22 0.9 S. maltophilia …”

Bacterial and Fungal Proteolytic Enzymes: Production, Catalysis and Potential Applications

“…For peptidase application, the protein structural stability is a crucial biochemical property favoring its feasibility for commercial use. Enzymes are susceptible to denaturation by different physicochemical agents, including deamination, proteolysis, oxidation, inhibition, and structural changes due to pH and temperature [82][83][84][85][86].…”

Thermostable xylanase from thermophilic fungi: Biochemical properties and industrial applications

“…Higher thermal stability is one of the fundamental requirements for the application of an enzyme in industrial processes; it increases the efficiency of enzyme. Therefore, searching for thermostable enzymes or improve the thermostability of enzymes has been the priority for researchers over the years (Nirmal and Laxman, 2014). The factors affecting thermostability are important for understanding the functions of proteins and their use in various industries (Ruller et al, 2008).…”