# Computational Prediction of the Protonation Sites of Ac-Lys-(Ala)n-Lys-NH2 Peptides through Conceptual DFT Descriptors

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## Abstract

**:**

## 1. Introduction

## 2. Theoretical Background

**r**atom of the radical cation or anion of a given molecule, respectively. The ASD over each atom of the radical cation and radical anion of the molecule gives the local nucleophilic P${}_{k}^{-}$ and electrophilic P${}_{k}^{+}$ Parr functions of the neutral molecule [6].

## 3. Settings and Computational Methods

## 4. Results and Discussion

## 5. Conclusions

## Supplementary Materials

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## Abbreviations

DFT | Density Functional Theory |

KS | Kohn-Sham |

E | Electronic Energy |

I | Ionization Potential |

A | Electron Affinity |

N | Number of Electrons |

AGE | Advanced Glycation Endproducts |

MEDT | Molecular Electron Density Theory |

SCF | Self Consistent Field |

KID | Koopmans in DFT |

HOMO | Higher Ocuppied Molecular Orbital |

LUMO | Lower Unocuppied Molecular Orbital |

IEF-PCM | Integral Equation Formalism–Polarized Continuum Model |

SMD | Solvation Model Density |

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**Sample Availability:**Not available.

**Table 1.**Average descriptors J${}_{I}$, J${}_{A}$, J${}_{HL}$, J${}_{\chi}$, J${}_{\eta}$, J${}_{\omega}$, J${}_{D1}$ for the KK, KAK, KA2K, KA3K, KA4K and KAK5 peptides calculated with the M11, M11L, MN12L, MN12SX, N12, and N12SX density functionals and the Def2TZVP basis set using water as as solvent simulated with the solvation model density (SMD) parametrization of the Integral Equation Formalism–Polarized Continuum Model (IEF-PCM) model.

J${}_{\mathit{I}}$ | J${}_{\mathit{A}}$ | J${}_{\mathbf{HL}}$ | J${}_{\mathit{\chi}}$ | J${}_{\mathit{\eta}}$ | J${}_{\mathit{\omega}}$ | J${}_{\mathit{D}1}$ | |
---|---|---|---|---|---|---|---|

M11 | 2.79 | 2.38 | 3.67 | 0.20 | 5.37 | 0.37 | 5.19 |

M11L | 1.66 | 0.07 | 1.67 | 0.80 | 1.73 | 0.17 | 1.91 |

MN12L | 1.87 | 0.14 | 1.88 | 0.87 | 2.01 | 0.8 | 2.20 |

MN12SX | 0.13 | 0.08 | 0.15 | 0.09 | 0.06 | 0.05 | 0.14 |

N12 | 1.40 | 0.22 | 1.44 | 0.59 | 1.62 | 0.10 | 1.74 |

N12SX | 0.00 | 0.07 | 0.07 | 0.03 | 0.07 | 0.03 | 0.08 |

**Table 2.**Condensed dual descriptors and electrophilic Parr functions P${}_{k}^{-}$ for the KK, KAK, KA2K, KA3K, KA4K, and KA5K peptides calculated with the MN12SX and N12SX density functionals and the Def2TZVP basis set using water as as solvent simulated with the SMD parametrization of the IEF-PCM model. MPA: Mulliken Population Analysis; HPA: Hirshfeld Population Analysis.

MN12SX | N12SX | |||||
---|---|---|---|---|---|---|

$\mathbf{\u2206}{\mathit{f}}_{\mathit{k}}$ | P${}_{\mathit{k}}^{-}$(mpa) | P${}_{\mathit{k}}^{-}$(hpa) | $\mathbf{\u2206}{\mathit{f}}_{\mathit{k}}$ | P${}_{\mathit{k}}^{-}$(mpa) | P${}_{\mathit{k}}^{-}$(hpa) | |

KK | −0.63 | 0.76 | 0.74 | −0.69 | 0.76 | 0.73 |

KAK | −0.62 | 0.76 | 0.73 | −0.69 | 0.76 | 0.73 |

KA2K | −0.71 | 0.81 | 0.78 | −0.74 | 0.78 | 0.73 |

KA3K | −0.63 | 0.76 | 0.74 | −0.69 | 0.76 | 0.73 |

KA4K | −0.71 | 0.81 | 0.78 | −0.74 | 0.81 | 0.78 |

KA5K | −0.71 | 0.81 | 0.78 | −0.74 | 0.81 | 0.78 |

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**MDPI and ACS Style**

Sastre, S.; Frau, J.; Glossman-Mitnik, D.
Computational Prediction of the Protonation Sites of Ac-Lys-(Ala)n-Lys-NH2 Peptides through Conceptual DFT Descriptors. *Molecules* **2017**, *22*, 458.
https://doi.org/10.3390/molecules22030458

**AMA Style**

Sastre S, Frau J, Glossman-Mitnik D.
Computational Prediction of the Protonation Sites of Ac-Lys-(Ala)n-Lys-NH2 Peptides through Conceptual DFT Descriptors. *Molecules*. 2017; 22(3):458.
https://doi.org/10.3390/molecules22030458

**Chicago/Turabian Style**

Sastre, Sebastián, Juan Frau, and Daniel Glossman-Mitnik.
2017. "Computational Prediction of the Protonation Sites of Ac-Lys-(Ala)n-Lys-NH2 Peptides through Conceptual DFT Descriptors" *Molecules* 22, no. 3: 458.
https://doi.org/10.3390/molecules22030458