Purification, kinetics and physical-chemistry characterization of periplaneta americana, Tenebrio molitor and Diatraca saccharalis digestive chymotrypsin / Purificação, caracterização físico-químico e cinética das quimotripsinas digestivas de Periplaneta americana, Tenebrio molitor e Diatraea saccharalis.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Chymotrypsins (EC 3.4.21.1) are serine proteases with 245 amino acids disposed in two double ?-barrel domains, being the active site locate between these two domains. The specificity study of endopeptidases was facilitated by the substrate binding site concept that is the active site of these enzymes. However there is not much information about the subsites specificity of insect chymotrypsins. The specificity study of insects chymotrypsins subsites of Periplaneta americana, Tenebrio molitor and Diatraea saccharalis showed higher substrate hydrolysis efficiency with Tyr in P1, however the Phe/Tyr proportion for different insects are varied. These differences have shown different specificities for insect chymotrypsins in P1. Meanwhile, this difference does not follow the position occupied by insects in evolutive scale, and it is less clear than those showed by the same insect trypsins were there is primary specificity cross. Like Diatraea saccharalis, the Periplaneta americana chymotrypsin breaks the substrate with Pro in P2. Nevertheless the same does not happen to Tenebrio molitor chymotrypsin with the higher kcat/Km for the peptide with Ala in P2, this preference may be related to the different conformation of Pro. The three studied chymotrypsins showed higher kcat/Km for the peptide with Ile in P3, what indicates that this subsite has a key role on these enzymes discrimination for substrates with specific amino acids in this position. The Periplaneta americana and Diatraea saccharalis chymotrypsins presented higher kcat/Km for the peptide with Ser in P1` evidencing that the hydroxyl group side chain presence in Ser and low side chain volume made this subsite more selective than Tenebrio molitor chymotrypsin with higher kcat/Km by Ala peptide. This study collaborates to a best knowledge about the subsite specificities of the insect digestive endopeptidases and the best inhibitors for purification or synthesis with direct action in insect digestive enzymes and to be utilized for transgenic plants or bio-insecticides production.

ASSUNTO(S)

caracterização cinética enzymatic characterization purification protein bioquímica de insetos enzimas digestivas insects chrymotrypsin protease

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