Luis Henrique de Barros Soares

Purification and properties of a transglutaminase produced by a Bacillus circulans strain isolated from the Amazon environment

A new microbial transglutaminase (EC 2.3.2.13) from a Bacillus circulans strain isolated from the aquatic Amazonian environment was purified and characterized. Enzyme purification started with (NH4)2SO4 ‘salting out’ and proceeded with liquid chromatography on Q‐Sepharose FF and octyl‐Sepharose 4 FF. The purification factor was approx. 150‐fold with a yield of 32%. The enzymes molecular mass was estimated as 45000 Da on SDS/PAGE. The purified transglutaminase had an optimum temperature of 47 °C, the optimum pH of the reaction was 7 and it presented no calcium‐dependent activity.

Physicochemical properties of three food proteins treated with transglutaminase

Three sources of food proteins were treated with microbial transglutaminase (EC 2.3.2.13) in order to assess changes in the physicochemical properties of reactivity, solubility, emulsification, and free amino groups of the formed polymers. Samples of lactic casein (LC), isolated soy protein (ISP), and hydrolysed animal protein (HAP), were incubated with the enzyme for one or two hours. LC and ISP showed a reduced solubility of 15% and 24% respectively, with HAP showing no alteration on solubility. Amino nitrogen content was 7%, 3% and 2% reduced for HAP, LC and ISP respectively. LC and ISP demonstrated lower emulsifying activity when they were enzymatically treated but the formed emulsions were stable, contrasting with HAP, which exhibited no changes in emulsifying properties.