The aim of the present work is to study some physical properties of microbial transglutaminase (MTGase) produced from a newly isolated strain of Streptomyces sp. Also, its application in producing Shamy bread from a mixture of wheat and corn flours was investigated. The results revealed that the enzyme exhibited optimum activity at 45 ᴼ C; it retained about 80% of the initial activity after incubation for one hour at this temperature. The optimum activity was at pH 6.5 and was stable at this pH for one hour. The cross-linking effect of the enzyme was tested through cross-linking of wheat dough prepared for Shamy bread. The results indicated that the enzyme have a cross-linking effects towards the free amino and thiol groups of wheat dough. The free amino groups of the wheat dough were 0.538 µM/ mg flour without adding the enzyme. It decreased to 0.378 µM/ mg flour when treated with the enzyme; the percent of reduction was 29.74. Mixing corn flour with wheat flour decreased the free amino groups of the resulted dough. It decreased to 0.248 µM/ mg flour in the sample treated with the enzyme and containing 30% corn flour with percentage of reduction 34.39. In general, increasing the percentage of corn flour in the blends treated with MTGase decreases the free thiol groups. The free thiol groups of the wheat dough (without enzyme) were 11.222µM/ g flour, it decreased to 10.342 µM/ g flour when treated with the enzyme, with percentage of reduction 7.849 %. When the levels of corn flour increased to 30% the free thiol groups decreased and the percent of the reduction increased to 8.575. It was noted that the prepared Shamy bread from dough containing 70% wheat flour and 30% corn flour and treated with the enzyme have a higher volume with pronounced improvement in the general appearance and quality than that without the enzyme.

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