Glutaminase activity

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... 

In the 3D structure of GatCAB solved at 2.3 A of resolution, the glutaminase active center and the binding site of the CCA end of tRNA are 30 A apart. The two sites are connected by a channel, mostly hydrophobic in the outside, but lined inside with a succession of alternating strictly conserved positive and negative residues. The structure suggests a proton relay mechanism that carries ammonia from one site to the other by repeated... 

Capacity of glycolysis (glucose conversion to lactate) Glutaminase activity (required for glutaminolysis) ... 

Table 2 gives a brief summary [IS], It seems important to mention 1-ASP also contains up to 10% l-glutaminase activity flhble 2]. As all purification proce-... 

Figure 9.46 L-Glutamate formation with respect to incubation time at 37°C due to the glutaminase activity. (From Unnithan et al., 1984.)...

Specific enzyme activities are markedly different among preparations Table 2 gives a brief summary [18], It seems important to mention 1-ASP also contains up to 10% 1-glutaminase activity (Table 2). As all purification procedures attempting to get rid of this activity have been unsuccessful so far and even recombinant 1-ASP has 1-glutaminase activity, it seems likely that hydrolysis of 1-glutamine is not mediated by a contaminating enzyme but by 1-ASP itself [19]. 

Table 2 Molecular Weights, Specific Enzyme Activity, and Glutaminase Activities of Four Different 1-ASP Preparations...

ASP source Molecular weight (kDa) Specific activity (U/g) Glutaminase activity (%)... 

Several requirements must be fulfilled for enzymes to be used for therapy large-scale availability, little acute or chronic toxicity, low glutaminase activity, reasonable in vivo half-life, high substrate affinity, high specific enzyme activity, oncolytic activity. As not all 1-ASPs fulfill these requirements, only two preparations are currently used E. coli and Erwinia. 

Matsuno T, Hirai H. Glutamine synthetase and glutaminase activities in various hepatoma cells. Biochemistry Int. 19(2) 219-225,... 

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