Open AccessThe Binding of Kirromycin to Elongation Factor Tu
Author(s) -
PINGOUD Alfred,
URBANKE Claus,
WOLF Heinz,
MAASS Guenter
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12294.x
Subject(s) - ef tu , ternary complex , gtp' , chemistry , circular dichroism , titration , gtpase , aminoacyl trna , stereochemistry , conformational change , elongation factor , crystallography , subtilisin , biophysics , enzyme , biochemistry , transfer rna , biology , organic chemistry , ribosome , rna , gene
The influence of kirromycin on the elongation factor Tu (EF‐Tu) in its binary and ternary complexes was investigated. The equilibrium constant for the binding of the antibiotic to EF‐Tu · GDP and EF‐Tu · GTP was determined by circular dichroism titrations to be 4 × 10 6 M −1 , and to EF‐Tu · GTP · aa‐tRNA by a combination of circular dichroism titrations and hydrolysis protection experiments to be 2 × 10 6 M −1 . In the presence of kirromycin the binding of aminoacyl‐tRNAs to EF‐Tu · GTP is weakened by a factor of two. The antibiotic changes the conformation of the ternary complex in such a way that the aminoacyl moiety of the aminoacyl‐tRNA is more accessible to the non‐enzymatic hydrolysis. It is concluded that this structural alteration is responsible for the inhibitory action of the antibiotic.