Metal ions play a variety of functions in proteins, spanning from the enhancement of structural stability in a conformation required for biological functions to the assistance in enzymatic processes.[1] An increasing attention has been paid to the study of mechanism of action of metallo-proteins as well as to the definition of their structural features. The use of low molecular weight 'model compounds' is a widely used approach to investigate metallo-protein properties, especially when structural details are not available or not yet unambiguous. In particular bicyclic peptides are known to be interesting models for the naturally occurring metal binding peptides and also to be able to mimic the three-dimensional structure of protein sites better than linear or monocyclic analogs. In our research group, bicyclic peptide models able to co-ordinate metal ions were designed and structurally characterized. In one of our studies we examined, by CD and NMR spectroscopy, a bicyclic undecapeptide designed to mimic structure and calcium binding properties of Calmodulin (CaM) site I.[2] The average model from RMD calculations exhibit good analogies with the natural site I. The model system, when compared with the reference system (Asp20-Glu31 segment in CaM), shows similar dimensions and an effective superimposition of the respective sequence segments. The remaining segments of the model peptide exhibit a bending that is intermediate between that of the free and Ca2+-coordinate site I. We also studied the conformation and calcium binding properties of a bicyclic peptide BCP2[3] which does not strictly reproduce any natural system. Indeed BCP2 belongs to a series of synthetic peptides designed to study, in a systematic way, the structure requirements for calcium binding ability. The spectroscopic characterization, via CD, NMR and RMD, shows that BCP2 is strikingly respondent to the design expectations. Here our results on these model peptide systems, which are able to co-ordinate calcium ion, will be discussed.

Calcium Binding model peptides : a spectrosopic study

D'AURIA, GABRIELLA;FALCIGNO, LUCIA;
2002

Abstract

Metal ions play a variety of functions in proteins, spanning from the enhancement of structural stability in a conformation required for biological functions to the assistance in enzymatic processes.[1] An increasing attention has been paid to the study of mechanism of action of metallo-proteins as well as to the definition of their structural features. The use of low molecular weight 'model compounds' is a widely used approach to investigate metallo-protein properties, especially when structural details are not available or not yet unambiguous. In particular bicyclic peptides are known to be interesting models for the naturally occurring metal binding peptides and also to be able to mimic the three-dimensional structure of protein sites better than linear or monocyclic analogs. In our research group, bicyclic peptide models able to co-ordinate metal ions were designed and structurally characterized. In one of our studies we examined, by CD and NMR spectroscopy, a bicyclic undecapeptide designed to mimic structure and calcium binding properties of Calmodulin (CaM) site I.[2] The average model from RMD calculations exhibit good analogies with the natural site I. The model system, when compared with the reference system (Asp20-Glu31 segment in CaM), shows similar dimensions and an effective superimposition of the respective sequence segments. The remaining segments of the model peptide exhibit a bending that is intermediate between that of the free and Ca2+-coordinate site I. We also studied the conformation and calcium binding properties of a bicyclic peptide BCP2[3] which does not strictly reproduce any natural system. Indeed BCP2 belongs to a series of synthetic peptides designed to study, in a systematic way, the structure requirements for calcium binding ability. The spectroscopic characterization, via CD, NMR and RMD, shows that BCP2 is strikingly respondent to the design expectations. Here our results on these model peptide systems, which are able to co-ordinate calcium ion, will be discussed.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/495545
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