Volumes of Individual Amino Acid Residues in Gas-Phase Peptide Ions

1999 ◽  
Vol 121 (16) ◽  
pp. 4031-4039 ◽  
Author(s):  
Anne E. Counterman ◽  
David E. Clemmer
Keyword(s):  
Amino Acid ◽  
Gas Phase ◽  
Individual Amino Acid ◽  
Amino Acid Residues ◽  
Peptide Ions

Novel Peptide Dissociation:  Gas-Phase Intramolecular Rearrangement of Internal Amino Acid Residues

1997 ◽  
Vol 119 (24) ◽  
pp. 5481-5488 ◽  
Author(s):  
Richard W. Vachet ◽  
Barney M. Bishop ◽  
Bruce W. Erickson ◽  
Gary L. Glish
Keyword(s):  
Amino Acid ◽  
Gas Phase ◽  
Intramolecular Rearrangement ◽  
Amino Acid Residues ◽  
Peptide Dissociation

scholarly journals Regulation of AE2-mediated Cl− Transport by Intracellular or by Extracellular pH Requires Highly Conserved Amino Acid Residues of the AE2 NH2-terminal Cytoplasmic Domain

2002 ◽  
Vol 120 (5) ◽  
pp. 707-722 ◽  
Author(s):  
A.K. Stewart ◽  
M.N. Chernova ◽  
B.E. Shmukler ◽  
S. Wilhelm ◽  
S.L. Alper
Keyword(s):  
Amino Acid ◽  
Anion Exchange ◽  
Cytoplasmic Domain ◽  
Weak Acid ◽  
Extracellular Ph ◽  
Individual Amino Acid ◽  
Amino Acid Residues ◽  
General Importance ◽  
Alanine Scan ◽  
Intracellular Alkalinization

We reported recently that regulation by intracellular pH (pHi) of the murine Cl−/HCO3− exchanger AE2 requires amino acid residues 310–347 of the polypeptide's NH2-terminal cytoplasmic domain. We have now identified individual amino acid residues within this region whose integrity is required for regulation of AE2 by pH. 36Cl− efflux from AE2-expressing Xenopus oocytes was monitored during variation of extracellular pH (pHo) with unclamped or clamped pHi, or during variation of pHi at constant pHo. Wild-type AE2–mediated 36Cl− efflux was profoundly inhibited by acid pHo, with a value of pHo(50) = 6.87 ± 0.05, and was stimulated up to 10-fold by the intracellular alkalinization produced by bath removal of the preequilibrated weak acid, butyrate. Systematic hexa-alanine [(A)6]bloc substitutions between aa 312–347 identified the greatest acid shift in pHo(50) value, ∼0.8 pH units in the mutant (A)6342–347, but only a modest acid-shift in the mutant (A)6336–341. Two of the six (A)6 mutants retained normal pHi sensitivity of 36Cl− efflux, whereas the (A)6 mutants 318–323, 336–341, and 342–347 were not stimulated by intracellular alkalinization. We further evaluated the highly conserved region between aa 336–347 by alanine scan and other mutagenesis of single residues. Significant changes in AE2 sensitivity to pHo and to pHi were found independently and in concert. The E346A mutation acid-shifted the pHo(50) value to the same extent whether pHi was unclamped or held constant during variation of pHo. Alanine substitution of the corresponding glutamate residues in the cytoplasmic domains of related AE anion exchanger polypeptides confirmed the general importance of these residues in regulation of anion exchange by pH. Conserved, individual amino acid residues of the AE2 cytoplasmic domain contribute to independent regulation of anion exchange activity by pHo as well as pHi.

scholarly journals Amino acid sequence of versutoxin, a lethal neurotoxin from the venom of the funnel-web spider Atrax versutus

1988 ◽  
Vol 250 (2) ◽  
pp. 401-405 ◽  
Author(s):  
M R Brown ◽  
D D Sheumack ◽  
M I Tyler ◽  
M E H Howden
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Gas Phase ◽  
Edman Degradation ◽  
Amino Acid Residues ◽  
Single Chain ◽  
Male And Female ◽  
Web Spider ◽  
Phase Protein ◽  
Protein Sequencer

The complete amino acid sequence of versutoxin, a lethal neurotoxic polypeptide isolated from the venom of male and female funnel-web spiders of the species Atrax versutus, was determined. Sequencing was performed in a gas-phase protein sequencer by automated Edman degradation of the S-carboxymethylated toxin and fragments of it produced by reaction with CNBr. Versutoxin consisted of a single chain of 42 amino acid residues. It was found to have a high proportion of basic residues and of cystine. The primary structure showed marked homology with that of robustoxin, a novel neurotoxin recently isolated from the venom of another funnel-web-spider species, Atrax robustus.

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