Characterization of contryphans from Conus loroisii and Conus amadis that target calcium channels

Sabareesh, Varatharajan; Gowd, Konkallu Hanumae; Ramasamy, P.; Sudarslal, S; Krishnan, K. S.; Sikdar, Siddhartha; Balaram, Padmanabhan

doi:10.1016/j.peptides.2006.07.009

Cited by 38 publications

(45 citation statements)

References 34 publications

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“…Cone snail samples were collected by Professor K. S. Krishnan and collaborators from the southeastern coast of India. Crude venom samples were obtained by dissecting the venom duct and extracting the total peptide mixture into alcohol solution [4,19]. Electrospray ionization (ESI) mass spectrometry studies were carried out on HPLC purified peptide fraction and also on crude venom mixtures using an on-line HPLC.…”

Section: Methodsmentioning

confidence: 99%

“…Contryphans are a group of single disulfide bond containing peptides obtained from the venom of predatory cone snails [4,20]. We have recently described the fragmentation of the intact disulfide bonded peptide under conditions of positive ion mass spectrometry in an attempt to directly sequence peptides from natural mixtures.…”

Section: Contryphanmentioning

confidence: 99%

“…Figure 5a and b compare the positive and negative ion mass spectra obtained for the contryphan Am 975 from Conus amadis [4,19]. Dramatic differences are evident from the distribution of product ions.…”

Section: Contryphanmentioning

confidence: 99%

“…Dramatic differences are evident from the distribution of product ions. In the positive ion mode, the intense cleavage products can be rationalized by postulating an initial fragmentation at the X-Pro bond [4,19,21,22]. In the positive ion mode, the single intense peak at m/z 959 corresponds to loss of NH 3 from the C-terminal primary amide group.…”

Section: Contryphanmentioning

confidence: 99%

“…The case of a contryphan, a cyclic peptide disulfide derived from Conus snail venom, illustrates the utility of negative ion mass spectrometry in disulfide identification. M ass spectrometric characterization of disulfide bonded peptides is generally achieved by the reduction of the S-S bond followed by alkylation [1][2][3][4] or by oxidation to sulfonic acid derivatives [5]. Subsequent gas-phase fragmentation results in readily identifiable backbone cleavage products.…”

mentioning

confidence: 99%

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Fragmentation of peptide disulfides under conditions of negative ion mass spectrometry: Studies of oxidized glutathione and contryphan

Thakur

Balaram

2008

J. Am. Soc. Mass Spectrom.

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The fragmentation of positive and negative ions of peptide disulfides under mass spectrometric conditions yields distinctly different product ion distributions. A negative ion upon collision induced dissociation yields intense product ions, which correspond to cleavage at the disulfide linkage. The complete assignment of the product ions obtained upon fragmentation of oxidized glutathione in an ion trap is presented. The cleavage at the disulfide site is mediated by abstraction of C ␣ H and C ␤ p H protons resulting in product ions derived by neutral loss of H 2 S 2 and H 2 S. The formation of peptide thioaldehydes and persulfides at the cysteine sites is established. Dehydroalanine formation at the Cys residue is predominant. The case of a contryphan, a cyclic peptide disulfide derived from Conus snail venom, illustrates the utility of negative ion mass spectrometry in disulfide identification. M ass spectrometric characterization of disulfide bonded peptides is generally achieved by the reduction of the S-S bond followed by alkylation [1][2][3][4] or by oxidation to sulfonic acid derivatives [5]. Subsequent gas-phase fragmentation results in readily identifiable backbone cleavage products. Several groups have focused on the mass spectrometric analysis of peptides containing intact disulfide bonds using both positive and negative ions for gas-phase fragmentation [6 -12]. In the case of positively charged peptide ions, disulfide bond fragmentation occurs with much lower efficiency than cleavage of backbone peptide bonds, under conditions of collision induced dissociation with non-mobile protons suggested to play an important role [11]. Restricted proton mobility along the polypeptide backbone has also been implicated in cases of disulfide cleavages in polypeptides, which have been cationized using gold (I) [7]. The use of metal ions as gas-phase disulfide cleavage agents has also been investigated [12]. In general, only limited information regarding structure can be derived from intact disulfide peptides in the positive ion mode. In contrast, several recent studies have emphasized the utility of negative ion mass spectrometry [7,10,[13][14][15][16][17][18]. Specifically, Bowie and coworkers have presented assignments of product ion spectra obtained by negative ion electrospray mass spectrometry of peptides containing both intra and inter molecular disulfide bond [10,18]. The present study complements the work of Bowie and coworkers and further provides mechanistic details by examining second generation product ions by using ion trap mass spectrometry.In the structural analysis of peptides containing intact disulfides, under negative ion conditions, proton abstraction from the C ␣ H and C ␤ H positions of the Cys residue results in diverse fragmentation reactions, leading to cleavage of disulfide linkages. In the case of peptides that contain labile peptide bonds, for example X-Pro sequences, preferential cleavage at these sites results in two linear chains linked by a disulfide bond, which then undergo further f...

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Section: Methodsmentioning

confidence: 99%

Section: Contryphanmentioning

confidence: 99%

Section: Contryphanmentioning

confidence: 99%