Bothropstoxin-I: amino acid sequence and function.
The complete amino acid sequence of bothropstoxin-I (BthTX-I), a myotoxin isolated from Bothrops jararacussu snake venom, is reported. The results show that BthTX-I is a Lys49 phospholipase A2 (PLA2)-like protein composed of a single polypeptide chain of 121 amino acid residues (M(r) = 13,720), containing one methionine and 14 half-cystines. Although deprived of any detectable PLA2 activity, BthTX-I reveals a high degree of sequence homology with Asp49-PLA2s and with other Lys49-myotoxins. Critical mutations--such as Leu5 for Phe5; Gln11 for X11; Asn28 for Tyr28; Leu32 for Gly32; Lys49 for Asp49; and Asp71 for Asn71--which are apparently involved with the decreasing or elimination of PLA2 activity, have been detected. The same mutations occurred in myotoxin II from Bothrops asper venom, but five extra changes--namely, Pro90 for Ser90; Gly111 for Asn111; His120 for Tyr120; Phe124 for Leu124; and Pro132 for Ala132--have been found relative to myotoxin II.
Cintra
A C
AC
Departamento de Bioquímica, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil.
Marangoni
S
S
Oliveira
B
B
Giglio
J R
JR
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010741:Phospholipases A / Q000737:chemistry; D054467:Phospholipases A2; D017386:Sequence Homology, Amino Acid; D012911:Snakes
D003435:Crotalid Venoms; C078097:bothropstoxin; D010741:Phospholipases A; D054467:Phospholipases A2