ECEPP Empirical Conformational Energy Program for Peptides

In ECEPP, the set of standardized parameters which characterize the geometry of the amino acid residues, as well as those introduced in the different terms of the potential function representing the interatomic interactions, are internally consistent. Such a set of empirical parameters was developed in 1974-75 and updated in 1983 and 1992. 

In ECEPP, the total empirical energy, Etot(rp), associated with the conformation Tp of a given molecule in the gas phase is represented by  

In ECEPP, the nonbonded interaction between designated donor and acceptor atoms capable of forming hydrogen bonds is considered as a special case. Under these circumstances, the term UnbiU j) is replaced by a hydrogen bond potential, f hb(L j)y of the form  

The donors (H atoms) are amine, amide, and hydroxyl hydrogens, and acceptors (X atoms) are uncharged ring nitrogens, amide nitrogens, or hydroxyl, ester carbonyl, or carboxylic acid oxygens. 

The electrostatic potential energy is computed as the sum of pairwise interactions between atom-centered monopole partial charges  

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D.R. Ripoll, H.A. Scheraga, ECEPP Empirical Conformational Energy Program for Peptides, in The Encyclopedia of Computational Chemistry, Vol. 2,... 

ECEPP Empirical conformational energy program for peptides... 

Some of the parameters that are used in the computer program ecepp (empirical conformational energy program for peptides) of Momany et al. (J. Phys. Chem. 1975, 79, 2361) are updated. The changes are based on experimental information that has become available since 1975,... 

ECEPP Empirical Conformational Energy Program for Peptides... 

ECEPP EMPIRICAL CONFORMATIONAL ENERGY PROGRAM FOR PEPTIDES... 

Several empirical potential functions are used to calculate the conformational energy of a polypeptide. The one in most frequent use in our laboratory is ECEPP (Empirical Conformational Energy Program for Peptides)(Momany et al., 1975 Pottle et al., 1980). It was parameterized (Momany et al., 1974a) and tested (Momany et al., 1974b) on the crystals listed in Table 1 of a paper by Scheraga (1974) and on gas-phase data (Momany et al.. 

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