A Protease from Thermoactinomyces thalpophilus THM-1; Characterisation and Application for Clinical Nutrition
Thomas JAENICKE*a, Don A COWANa,b, and John M WARDa,b
a Department of Biochemistry and Molecular Biology, University College London, UK
b Helix Biotechnology ltd., Darwin Building, Gower Street, London, WC 1E 6BT, UK
Extremophilic bacteria are an useful source of novel enzymatic activities. We have isolated a thermophilic micro-organism which produces an extracellular protease that is highly non-specific and particularly suitable for producing di- and tri-peptide rich protein hydrolysates which find application for clinical use. Traditionally partial peptide hydrolysate mixtures are used as oral and enteral nutritional supplements in post operative and protein-building diets. The world market for such nutritional supplements is estimated at over US$ 450 M.
A novel strain of Thermoactinomyces thalpophilus, THM-1, was isolated from a soil sample. Its extracellular protease exhibits its maximum activity at alkaline pH and it has a temperature optimum of about 70℃. It belongs to the family of serine proteases and requires Ca2+ ions to maintain thermostability at temperatures above 50℃. Milk proteins were found to be preferred substrates whereas plant proteins were digested only marginally. At optimal conditions, casein was digested nearly completely to amino acids, but under slightly changed conditions of incubation temperature and pH, up to 40% of the substrate was converted to di- and tri-peptides as measured by CuII SephadexTM column chromatography. Further optimisation revealed whey protein to be a better substrate for the production of nutritional hydrolysates enriched in di- and tri-peptides, yielding up to 66% di- and tri-peptides and less than 3% amino acids. Comparison of the digestion pattern with proteases from Th. thalpophilus strains deposited in several culture collections marked PTHM-1 as unique.
