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001-es BibID:	BIBFORM052923
Első szerző:	Luna-Ramirez, Karen
Cím:	Structure, Molecular Modeling, and Function of the Novel Potassium Channel Blocker Urotoxin Isolated from the Venom of the Australian Scorpion Urodacus yaschenkoi / Karen Luna-Ramirez, Adam Bartok, Rita Restano-Cassulini, Veronica Quintero-Hernández, Fredy I. V. Coronas, Janni Christensen, Christine E. Wright, Gyorgy Panyi, Lourival D. Possani
Dátum:	2014
ISSN:	1521-0111
Megjegyzések:	This communication reports the structural and functional characterization of urotoxin, the first K(+) channel toxin isolated from the venom of the Australian scorpion Urodacus yaschenkoi. It is a basic peptide consisting of 37 amino acids with an amidated C-terminal residue. Urotoxin contains eight cysteines forming four disulfide bridges with sequence similarities resembling the ?-potassium channel toxin 6 (?-KTx-6) subfamily of peptides; it was assigned the systematic number of ?-KTx-6.21. Urotoxin is a potent blocker of human voltage-gated potassium channel (Kv)1.2 channels, with an IC50 of 160 pM, whereas its affinity for other channels tested was in the nanomolar range (hKv1.1, IC50 = 253 nM; hKv1.3, IC50 = 91 nM; and hKCa3.1, IC50 = 70 nM). The toxin had no effect on hKv1.4, hKv1.5, human ether-ℓa-go-go-related gene type 1 (hERG1), or human ether-ℓa-go-go-like (hELK2) channels. Multiple sequence alignments from the venom gland transcriptome showed the existence of four other new peptides similar to urotoxin. Computer modeling of urotoxin's three-dimensional structure suggests the presence of the ?/?-scaffold characteristic of other scorpion toxins, although very likely forming an uncommon disulfide pairing pattern. Using molecular dynamics, a model for the binding of this peptide to human Kv1.2 and hKv1.1 channels is presented, along with the binding of an in silico mutant urotoxin (Lys25Ala) to both channels. Urotoxin enriches our knowledge of K(+) channel toxins and, due to its high affinity for hKv1.2 channels, it may be a good candidate for the development of pharmacologic tools to study the physiologic functions of K(+) channels or related channelopathies and for restoring axonal conduction in demyelinated axons.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban scorpion toxin potassium channel
Megjelenés:	Molecular Pharmacology. - 86 : 1 (2014), p. 28-41. -
További szerzők:	Bartók Ádám (1984-) (biotechnológus) Restano-Cassulini, Rita Quintero-Hernandez, Veronica Coronas, Fredy I. V. Christensen, Janni Wright, Christine E. Panyi György (1966-) (biofizikus) Possani, Lourival Domingos
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001-es BibID:	BIBFORM063758
Első szerző:	Olamendi-Portugal, Timoteo
Cím:	Isolation, chemical and functional characterization of several new K+-channel blocking peptides from the venom of the scorpion Centruroides tecomanus / Timoteo Olamendi-Portugal, Adam Bartok, Fernando Zamudio-Zuniga, Andras Balajthy, Baltazar Becerril, Gyorgy Panyi, Lourival D. Possani
Dátum:	2016
ISSN:	0041-0101
Megjegyzések:	AbstractSix new peptides were isolated from the venom of the Mexican scorpion Centruroides tecomanus; their primary structures were determined and the effects on ion channels were verified by patch-clamp experiments. Four are K(+)-channel blockers of the ?-KTx family, containing 32 to 39 amino acid residues, cross-linked by three disulfide bonds. They all block Kv1.2 in nanomolar concentrations and show various degree of selectivity over Kv1.1, Kv1.3, Shaker and KCa3.1 channels. One peptide has 42 amino acids cross-linked by four disulfides; it blocks ERG-channels and belongs to the ?-KTx family. The sixth peptide has only 32 amino acid residues, three disulfide bonds and has no effect on the ion-channels assayed. It also does not have antimicrobial activity. Systematic numbers were assigned (time of elution on HPLC): ?-KTx 10.4 (time 24.1); ?-KTx 2.15 (time 26.2); ?-KTx 2.16 (time 23.8); ?-KTx 2.17 (time 26.7) and ?-KTx 1.9 (elution time 29.6). A partial proteomic analysis of the short chain basic peptides of this venom, which elutes on carboxy-methyl-cellulose column fractionation, is included. The pharmacological properties of the peptides described in this study may provide valuable tools for understanding the structure-function relationship of K(+) channel blocking scorpion toxins.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Toxicon 115 (2016), p. 1-12. -
További szerzők:	Bartók Ádám (1984-) (biotechnológus) Zamudio, Fernando Z. Balajthy András (1988-) (általános orvos) Becerril, Baltazar Panyi György (1966-) (biofizikus) Possani, Lourival Domingos
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001-es BibID:	BIBFORM050051
Első szerző:	Schwartz, Elisabeth F.
Cím:	OcyKTx2, a new K+-channel toxin characterized from the venom of the scorpion Opisthacanthus cayaporum / Elisabeth F. Schwartz, Adam Bartok, Carlos Alberto Schwartz, Ferenc Papp, Froylan Gomez-Lagunas, Gyorgy Panyi, Lourival D. Possani
Dátum:	2013
Megjegyzések:	Opisthacanthus cayaporum belongs to the Liochelidae family, and the scorpions from this genus occur in southern Africa, Central America and South America and, therefore, can be considered a true Gondwana heritage. In this communication, the isolation, primary structure characterization, and K(+)-channel blocking activity of new peptide from this scorpion venom are reported. OcyKTx2 is a 34 amino acid long peptide with four disulfide bridges and molecular mass of 3807 Da. Electrophysiological assays conducted with pure OcyKTx2 showed that this toxin reversibly blocks Shaker B K(+)-channels with a Kd of 82 nM, and presents an even better affinity toward hKv1.3, blocking it with a Kd of approximately 18 nM. OcyKTx2 shares high sequence identity with peptides belonging to subfamily 6 of alpha-KTxs that clustered very closely in the phylogenetic tree included here. Sequence comparison, chain length and number of disulfide bridges analysis classify OcyKTx2 into subfamily 6 of the alpha-KTx scorpion toxins (systematic name, alpha-KTx6.17)
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban analysis article Brazil Peptides Research Research Support Scorpions Support Toxins
Megjelenés:	Peptides. - 46 (2013), p. 40-46. -
További szerzők:	Bartók Ádám (1984-) (biotechnológus) Schwartz, Carlos Alberto Papp Ferenc (1979-) (biofizikus) Gomez-Lagunas, Froylan Panyi György (1966-) (biofizikus) Possani, Lourival Domingos
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