Glutaminase-Asparaginase (Pseudomonas 7A)

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Function

L-asparaginase is an enzyme that converts L-asparagine into asparctic acid and ammonia. In adition this enzyme have a side activity analogous to previous one, which is the catalysis of D-glutamine into glutamate and ammonia.

Disease

Lymphoblastic Acute Leukemia, is a blood cancer that affects mainly childs (2-5 age); consists of non-controled proliferation of lymphocytic lineages since lymphoblasts to younges lymphocitic cells.

Relevance

Cancer cells are unable to perform synthesis of L-asparagine due to the lack of Asparagine Synthetase enzyme, which means that all source of L-asparagine is exogenous, unlike normal cells that can synthesize their own L-asparagine. When bacterial L-asparaginase is injected into the bloodstream, circulating L-asparagine is depleted, so cancer cells become unable to perform protein synthesis, that leads affected cells to apoptosis without harm to normal cells.

Structural highlights

Pseudomonas 7A Glutaminase-Asparaginase (PGA) consists of a tetrameric structure. Each is identical and possesses 337 residues. In the amminoterminal portion of each monomer, is able to identify and , unlike the carboxyl-terminal domain which have and , you can also note that 5 beta-strands of the sheet are parallel and 4 are parallel. The PGA structure exhibit 4 active sites, they can be found in the intersection of monomers between the first and the third parallel beta sheets and loops from the carboxyl-terminal of the adjacent subunit, being the the loop from carboxyl terminal and really important on catalysis due to their high flexibility; the main residues of this loop are Thr20, tyr34 and gly40. In adition to flexible loop, there's a rigid group that takes part on catalysis and is represented by residues

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