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|Type:||Artigo de periódico|
|Title:||Amino Acid Sequence Of Piratoxin-ii, A Myotoxic Lys49 Phospholipase A2 Homologue From Bothrops Pirajai Venom|
|Abstract:||The complete amino acid sequence of the 121 amino acid residues of piratoxin II, a phospholipase A2 like myotoxin from Bothrops pirajai venom, is reported. PrTX-II is a basic protein with a molecular mass of 13740 Da, a calculated pI of 9.03, but an experimental pI of 8.4 ± 0.2, showing sequence similarity with other bothropic (90-99%) or non-bothropic (~ 80%) Lys49 PLA2-like myotoxins. This similarity falls to ~ 70% when this sequence is aligned with that of Asp49 PLA2. Due to the substitution of Asp49 by Lys49 and alterations in the calcium binding loop structure, as the replacement of Gly32 by Leu32, piratoxin-II shows no PLA2 activity when assayed on egg yolk. Piratoxin-II showed the same primary structure as piratoxin-I, except that it has Lys116 for Leu116. Despite this slightly higher basicity at the C-terminal region, piratoxin-II was shown to be less myotoxic than piratoxin-I. The change Leu → Lys induced an alteration of the molecule surface shape and probably of the environment charge high enough to slightly decrease the myotoxic activity. When aligned with B. jararacussu bothropstoxin-I and with B. asper Basp-II, piratoxin-II revealed a single (position 132) and a quintuple (positions 17, 90, 111, 120 and 132) amino acid substitution, respectively, suggesting a common evolutionary origin for these three myotoxins. (C) 2000 Societe francaise de biochimie et biologie moleculaire / Editions scientifiques et medicales Elsevier SAS.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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