Glutaminase specificity

Laake JH, Takumi Y, Eidet J, Torgner lA, Roherg B, Kvamme E, Ottersen OP (1999) Postembedding immunogold labelling reveals subcellular localization and pathway-specific enrichment of phosphate-activated glutaminase in rat cerebellum. Neuroscience 88 ] 137-1151. 

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. 

One can be reasonably certain of specific inactivation if (1) dramatic inhibition of glutamine-dependent activity (or glutaminase activity) occurs without appreciable inhibition of other reactions catalyzed by the... 

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