Pescador: the PEptides in Solution ConformAtion Database: Online Resource

In recent years a large body of data has been obtained from Nuclear Magnetic Resonance and Circular Dichroism experiments on the influence of the amino acid sequence and various other parameters on the conformational state of peptides in solution. Interpreting the experimental data in terms of the conformational populations of the peptides remains a key problem, for which current solutions leave appreciable room for improvement. Considering that making this body of data available for surveys and analysis should be instrumental in tackling the problem, we undertook the development of Pescador: The `PEptides in Solution ConformAtion Database: Online Resource'. Pescador contains data from NMR and CD spectroscopy on peptides in solution as well as information on the structural parameters derived from these data. It also features specialized Web-based tools for data deposition, and means for readily accessing the stored information for analysis purposes. To illustrate the use of the database in deriving information for the conformational analysis of peptides, we show how the alpha proton -values stored in Pescador and measured by NMR for different peptides in different laboratories can be used to derive a new set of `random coil' chemical shift values. Firstly, we show these values to be very similar to those obtained experimentally for model peptides in water, and their variation with increasing Tri-Fluoro-Ethanol (TFE) concentration is similar to that reported for model peptides. We show, furthermore, that the chemical shift data in Pescador can be used to derive correction factors that take into account effects of neighboring residues. These correction factors compare favorably with those recently derived from a series of model GGXGG peptides Schwarzinger_e-valuesstoredinPescadorandmeasuredbyNMRfordifferentpeptidesindifferentlaboratoriescanbeusedtoderiveanewsetof`randomcoil'chemicalshiftvalues.Firstly,weshowthesevaluestobeverysimilartothoseobtainedexperimentallyformodelpeptidesinwater,andtheirvariationwithincreasingTri-Fluoro-Ethanol(TFE)concentrationissimilartothatreportedformodelpeptides.Weshow,furthermore,thatthechemicalshiftdatainPescadorcanbeusedtoderivecorrectionfactorsthattakeintoaccounteffectsofneighboringresidues.ThesecorrectionfactorscomparefavorablywiththoserecentlyderivedfromaseriesofmodelGGXGGpeptides Schwarzinger_etal. These encouraging results suggest that, as the quantity of NMR data on peptide deposited in Pescador increases, surveys of these data should be a valuable means of deriving key parameters for the analysis of peptide conformation.