Abstract
Trifluoroacetic acid (TFA) may be the cause of the bottleneck in high resolution structure determination for protein-peptide complexes. Fragment based drug design often involves the use of synthetic peptides which contain TFA (excipient). Our goal was to explore the effects of this excipient on a model complex: centrin-melittin-TFA. We performed Fourier transform infrared, two-dimensional infrared correlation spectroscopies and spectral simulations to analyze the amide I'/I'* band for the components and the ternary complex. Melittin (MLT) was observed to have increased helicity upon its interaction with centrin, followed by the thermally induced aggregation of MLT within the ternary complex in the TFA presence.
Highlights
Trifluoroacetic acid (TFA) is commonly found as excipient in synthetic peptides
The centrin-MLT complex has been studied by our group and its structure has been determined in the absence of TFA.19
Protein aggregation at the initial state of the sample prior to performing any crystallization screens may well be the cause of the bottleneck observed in high resolution structure determination of protein-peptide complexes
Summary
Trifluoroacetic acid (TFA) is commonly found as excipient in synthetic peptides. The presence of this excipient is due to the process of solid phase synthesis, whereby this strong counter ion is used to remove the protecting group and direct the synthesis of the peptide. The third component in the complex studied is centrin, a highly conserved calcium binding protein (CaBP), belonging the tenth largest family of proteins within the mammalian genome, the EF-hand superfamily.. The centrin-MLT complex has been studied by our group and its structure has been determined in the absence of TFA.. Protein aggregation at the initial state of the sample prior to performing any crystallization screens may well be the cause of the bottleneck observed in high resolution structure determination of protein-peptide complexes. It is possible that the presence of excipients can induce protein aggregation and prevents the successful crystallization of a)Contributed paper, published as part of a Special Topic: Invited Papers of the 2nd International BioXFEL Conference, 2329-7778/2015/2(4)/041711/11
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