Glutaminase

This enzyme catalyzes the hydrolysis of glutamine (Formula 2.113). For meat preparations, the addition of an enzyme preparation from Bacillus subtilis is under discussion. It increases the concentration of glutamic acid, which substantially contributes to the taste of meat. 

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Deamidation of soy and other seed meal proteins by hydrolysis of the amide bond, and minimization of the hydrolysis of peptide bonds, improves functional properties of these products. For example, treatment of soy protein with dilute (0.05 A/) HCl, with or without a cation-exchange resin (Dowex 50) as a catalyst (133), with anions such as bicarbonate, phosphate, or chloride at pH 8.0 (134), or with peptide glutaminase at pH 7.0 (135), improved solubiHty, whipabiHty, water binding, and emulsifying properties. 

Glutamine Glutaminase Glutamic acid, NHf Tris pH 7 NH -glass ... 

Figure 29-8. The glutaminase reaction proceeds essentially irreversibly in the direction of glutamate and NH/ formation. Note that the amide nitrogen, not the a-amino nitrogen, is removed.

Glutamine synthase converts NH3 to nontoxic glutamine. Glutaminase releases NH3 for use in urea synthesis. 

Curthoys NP, Watford M Regulation of glutaminase activity and glutamine metabolism. Annu Rev Nutr 1995 15 133. 

Table 4.1 Catalytic properties and inhibition by glutamyl-y-boronate of the glutaminase activity of bacterial Glu-tRNAGln amidotransferase... 

Glutamate, glutamine Coimmobilized glutamate oxidase + glutaminase, Luminol-H202 CL 0.1 (J.M glutamate, 1 (J.M glutamine 44... 

Hogstad, S., Svenneby, G., Torgner, I. A. etal. Glutaminase in neurons and astrocytes cultured from mouse brain kinetic properties and effects of phosphate, glutamate, and ammonia. Neurochem. Res. 13 383-388,1988. 

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