Lipopolysaccharide-protein interactions: Determination of dissociation constants by affinity electrophoresis

1989 ◽  
Vol 10 (12) ◽  
pp. 848-852 ◽  
Author(s):  
Petra Borneleit ◽  
Bernd Blechschmidt ◽  
Hans-Peter Kleber
Keyword(s):  
Protein Interactions ◽  
Dissociation Constants ◽  
Affinity Electrophoresis

Determination of acidic dissociation constants of L-phenylalanyl-glycine and L-alanyl-L-alanine in water using ab initio methods

2014 ◽  
Vol 2 (42) ◽  
pp. 263-263
Author(s):  
Farhoush Kiani ◽  
Mahmoud Tajbakhsh ◽  
Fereydoon Ashrafi ◽  
Nesa Shafiei ◽  
Azar Bahadori ◽  
...  
Keyword(s):  
Ab Initio ◽  
Dissociation Constants ◽  
Ab Initio Methods ◽  
Acidic Dissociation

scholarly journals Structural design principles for specific ultra-high affinity interactions between colicins/pyocins and immunity proteins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Avital Shushan ◽  
Mickey Kosloff
Keyword(s):  
Protein Interactions ◽  
Structural Elements ◽  
Protein Protein Interactions ◽  
Immunity Protein ◽  
Rational Engineering ◽  
High Affinity ◽  
Comparative Structure ◽  
Polar Interactions ◽  
Exquisite Specificity

AbstractThe interactions of the antibiotic proteins colicins/pyocins with immunity proteins is a seminal model system for studying protein–protein interactions and specificity. Yet, a precise and quantitative determination of which structural elements and residues determine their binding affinity and specificity is still lacking. Here, we used comparative structure-based energy calculations to map residues that substantially contribute to interactions across native and engineered complexes of colicins/pyocins and immunity proteins. We show that the immunity protein α1–α2 motif is a unique structurally-dissimilar element that restricts interaction specificity towards all colicins/pyocins, in both engineered and native complexes. This motif combines with a diverse and extensive array of electrostatic/polar interactions that enable the exquisite specificity that characterizes these interactions while achieving ultra-high affinity. Surprisingly, the divergence of these contributing colicin residues is reciprocal to residue conservation in immunity proteins. The structurally-dissimilar immunity protein α1–α2 motif is recognized by divergent colicins similarly, while the conserved immunity protein α3 helix interacts with diverse colicin residues. Electrostatics thus plays a key role in setting interaction specificity across all colicins and immunity proteins. Our analysis and resulting residue-level maps illuminate the molecular basis for these protein–protein interactions, with implications for drug development and rational engineering of these interfaces.

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