Isolation, purification and characterisation of transglutaminase from rosemary (Rosmarinus officinalis L.) leaves.

BACKGROUND: Rosemary (Rosmarinus officinalis L.) is a spice and medicinal herb widely used around the world of the natural antioxidants, and it has been widely accepted as one of the spices with the highest antioxidant activity. Transglutaminase (EC 2.3.2.13: TGase) is an enzyme capable of catalysing acyl transfer reactions by introducing covalent cross-links between proteins, as well as peptides and various primary amines. TGase activity in plants was first observed in pea seedlings, and subsequently found in organs of both lower and higher plants. Recently. TGase has captured researchers' interest due to its attractive potential application in food industries. Therefore, the objectives of this study are isolation and purification of TGase from new plant source rosemary (Rosmarinus officinalis L.) leaves at the laboratory scale. Moreover, investigation of the biochemical properties of the purified TGase to provide a suitable TGase enzyme for food industry applications are in focus.

MATERIAL AND METHODS: Rosemary (Rosmarinus officinalis L.) leaves was used as a new plant source to TGase. The biochemical characteristics of the crude and purified enzyme were determined.

RESULTS: Rosemary (Rosmarinus officinalis L.) TGase was purified to homogeneity by successive three purification steps including ammonium sulfate precipitatation, ion exchange chromatography on DEAE-Sephadex A-50 column and Size exclusion column chromatography on Sephadex G-100 column. Under experimental conditions. 20-30% of ammonium sulfate saturation in the enzyme solution had a high yield of enzyme activity could be obtained. The purified enzyme from the Sephadex G-100 column had 21.35% yield with increased about 7.31 in purification fold. Rosemary TGase exhibited optimum activity at pH 7.0 and 55°C for the catalytic reaction of hydroxylarnine and Z-Gln-Gly. The purified TGase almost maintained full activity after incubation for 15 ruin up to 60°C and it was completely inactivated at 85°C. The rosemary TGase was stimulated at 2-6 rnM CaCl2 concentrations while it lost about 5-20% from its activity by increasing CaCl2 concentration. Sodium chloride (2-14%) shows no noticeable inhibition of the purified TGase activity. Mg+2, Ba+2 were acivited by the purified TGase while it was str ongly inhibited by Fe+2, moderately by Cir2 and Mn+2.

CONCLUSION: This paper reports on the purification and characterisation of TGase from newly isolated plant, rosemary (Rosmarinus officinalis L.) leaves. Finding results of the TGase properties make this enzyme a good candidate for application in the food industry. However, additional work is required to increase activity yield during extraction and purification for commercial scale of TGase from this plant.