scholarly journals Selective molecular recognition of arginine by anionic salt bridge formation with bis-phosphate crown ethers: implications for gas phase peptide acidity from adduct dissociation

2004 ◽  
Vol 15 (4) ◽  
pp. 616-624 ◽  
Author(s):  
Ryan R. Julian ◽  
J. L. Beauchamp
Keyword(s):  
Molecular Recognition ◽  
Gas Phase ◽  
Crown Ethers ◽  
Salt Bridge ◽  
Bridge Formation ◽  
Anionic Salt

scholarly journals Cooperative Salt Bridge Stabilization of Gas-Phase Zwitterions in Neutral Arginine Clusters

2002 ◽  
Vol 106 (1) ◽  
pp. 32-34 ◽  
Author(s):  
Ryan R. Julian ◽  
J. L. Beauchamp ◽  
William A. Goddard
Keyword(s):  
Gas Phase ◽  
Salt Bridge

Vibrational Signature of Charge Solvation vs Salt Bridge Isomers of Sodiated Amino Acids in the Gas Phase

2004 ◽  
Vol 126 (6) ◽  
pp. 1836-1842 ◽  
Author(s):  
Catherine Kapota ◽  
Joël Lemaire ◽  
Philippe Maître ◽  
Gilles Ohanessian
Keyword(s):  
Amino Acids ◽  
Gas Phase ◽  
Salt Bridge ◽  
Charge Solvation

scholarly journals Rational design of new NO and redox sensitivity into connexin26 hemichannels

Open Biology ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 140208 ◽  
Author(s):  
Louise Meigh ◽  
Daniel Cook ◽  
Jie Zhang ◽  
Nicholas Dale
Keyword(s):  
Redox Potential ◽  
Rational Design ◽  
Salt Bridge ◽  
Disulfide Bridge ◽  
Wild Type ◽  
No Donors ◽  
Bridge Formation ◽  
Redox Sensitivity ◽  
Intracellular Redox

CO 2 directly opens hemichannels of connexin26 (Cx26) by carbamylating K125, thereby allowing salt bridge formation with R104 of the neighbouring subunit in the connexin hexamer. The formation of the inter-subunit carbamate bridges within the hexameric hemichannel traps it in the open state. Here, we use insights derived from this model to test whether the range of agonists capable of opening Cx26 can be extended by promoting the formation of analogous inter-subunit bridges via different mechanisms. The mutation K125C gives potential for nitrosylation on Cys125 and formation of an SNO bridge to R104 of the neighbouring subunit. Unlike wild-type Cx26 hemichannels, which are insensitive to NO and NO 2 − , hemichannels comprising Cx26 K125C can be opened by NO 2 − and NO donors. However, NO 2 − was unable to modulate the doubly mutated (K125C, R104A) hemichannels, indicating that an inter-subunit bridge between C125 and R104 is required for the opening action of NO 2 − . In a further test, we introduced two mutations into Cx26, K125C and R104C, to allow disulfide bridge formation across the inter-subunit boundary. These doubly mutated hemichannels open in response to changes in intracellular redox potential.

Molecular basis for defective secretion of the Z variant of human alpha-1-proteinase inhibitor: secretion of variants having altered potential for salt bridge formation between amino acids 290 and 342

1989 ◽  
Vol 9 (4) ◽  
pp. 1406-1414
Author(s):  
A A McCracken ◽  
K B Kruse ◽  
J L Brown
Keyword(s):  
Amino Acid ◽  
Proteinase Inhibitor ◽  
Conformational Stability ◽  
Point Mutations ◽  
Salt Bridge ◽  
Site Directed Mutagenesis ◽  
Wild Type ◽  
Functional Importance ◽  
Bridge Formation ◽  
Cos Cells

Human alpha-1-proteinase inhibitor (A1PI) deficiency, associated with the Z-variant A1PI (A1PI/Z) gene, results from defective secretion of the inhibitor from the liver. The A1PI/Z gene exhibits two point mutations which specify amino acid substitutions, Val-213 to Ala and Glu-342 to Lys. The functional importance of these substitutions in A1PI deficiency was investigated by studying the secretion of A1PI synthesized in COS cells transfected with A1PI genes altered by site-directed mutagenesis. This model system correctly duplicates the secretion defect seen in individuals homozygous for the A1PI/Z allele and shows that the substitution of Lys for Glu-342 alone causes defective secretion of A1PI. The substitution of Lys for Glu-342 eliminates the possibility for a salt bridge between residues 342 and 290, which may decrease the conformational stability of the molecule and thus account for the secretion defect. However, when we removed the potential to form a salt bridge from the wild-type inhibitor by changing Lys-290 to Glu (A1PI/SB-290Glu), secretion was not reduced to the 19% of normal level seen for A1PI/Z-342Lys; in fact, 75% of normal secretion was observed. When the potential for salt bridge formation was returned to A1PI/Z-342Lys by changing Lys-290 to Glu, only 46% of normal secretion was seen. These data indicate that the amino acid substitution at position 342, rather than the potential to form the 290-342 salt bridge, is the critical alteration leading to the defect in A1PI secretion.

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