Snake neurotoxins are short all-β proteins that display a complex organization of the disulfide bonds: two bonds connect consecutive cysteine residues (C43-C54, C55-C60), and two bonds intersect when bridging (C3-C24, C17-C41) to form a particular structure classified as "disulfide β-cross". We investigated the oxidative folding of a neurotoxin variant, named α62, to define the chemical nature of the three-disulfide intermediates that accumulate during the process in order to describe in detail its folding pathway. These folding intermediates were separated by reverse-phase HPLC, and their disulfide bonds were identified using a combination of tryptic hydrolysis, manual Edman degradation, and mass spectrometry. Two dominant intermediates containing three native disulfide bonds were identified, lacking the C43-C54 and C17-C41 pairing and therefore named des-[43-54] and des-[17-41], respectively. Both species were individually allowed to reoxidize under folding conditions, showing that des-[17-41] was a fast-forming nonproductive intermediate that had to interconvert into the des-[43-54] isomer before forming the native protein. Conversely, the des-[43-54] intermediate appeared to be the immediate precursor of the oxidized neurotoxin. A kinetic model for the folding of neurotoxin α62 which fits with the observed time-course accumulation of des-[17-41] and des-[43-54] is proposed. The effect of turn 2, located between residues 17 and 24, on the overall kinetics is discussed in view of this model.

Slow folding of three-fingered toxins is associated with the accumulation of native disulfide-bonded intermediates / Ruoppolo, Margherita; Talamo, F.; Pucci, Pietro; Moutiez, M.; Quemeneur, E.; Menez, A.; Marino, G.. - In: BIOCHEMISTRY. - ISSN 0006-2960. - 40:50(2001), pp. 15257-15266. [10.1021/bi0111956]

Slow folding of three-fingered toxins is associated with the accumulation of native disulfide-bonded intermediates.

RUOPPOLO, MARGHERITA;PUCCI, PIETRO;
2001

Abstract

Snake neurotoxins are short all-β proteins that display a complex organization of the disulfide bonds: two bonds connect consecutive cysteine residues (C43-C54, C55-C60), and two bonds intersect when bridging (C3-C24, C17-C41) to form a particular structure classified as "disulfide β-cross". We investigated the oxidative folding of a neurotoxin variant, named α62, to define the chemical nature of the three-disulfide intermediates that accumulate during the process in order to describe in detail its folding pathway. These folding intermediates were separated by reverse-phase HPLC, and their disulfide bonds were identified using a combination of tryptic hydrolysis, manual Edman degradation, and mass spectrometry. Two dominant intermediates containing three native disulfide bonds were identified, lacking the C43-C54 and C17-C41 pairing and therefore named des-[43-54] and des-[17-41], respectively. Both species were individually allowed to reoxidize under folding conditions, showing that des-[17-41] was a fast-forming nonproductive intermediate that had to interconvert into the des-[43-54] isomer before forming the native protein. Conversely, the des-[43-54] intermediate appeared to be the immediate precursor of the oxidized neurotoxin. A kinetic model for the folding of neurotoxin α62 which fits with the observed time-course accumulation of des-[17-41] and des-[43-54] is proposed. The effect of turn 2, located between residues 17 and 24, on the overall kinetics is discussed in view of this model.
2001
Slow folding of three-fingered toxins is associated with the accumulation of native disulfide-bonded intermediates / Ruoppolo, Margherita; Talamo, F.; Pucci, Pietro; Moutiez, M.; Quemeneur, E.; Menez, A.; Marino, G.. - In: BIOCHEMISTRY. - ISSN 0006-2960. - 40:50(2001), pp. 15257-15266. [10.1021/bi0111956]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/155539
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