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A Mathematical Model To Predict the Partitioning of Peptides and Peptide‐Modified Proteins in Aqueous Two‐Phase Systems
Author(s) -
Eiteman Mark A.,
Hassinen Cynthia,
Veide Andres
Publication year - 1994
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp00029a009
Subject(s) - peptide , phase (matter) , aqueous solution , chemistry , biological system , biochemistry , biology , organic chemistry
A mathematical procedure was developed to predict the partition coefficients of the peptides AIIP, AWWP, AIIPAIIP and AWWPAWWP in poly(ethylene glycol) (PEG)/ phosphate aqueous two‐phase systems from amino acid hydrophobicities. In general, peptides containing tryptophan partition more into the PEG‐enriched upper phase than analogous peptides containing isoleucine. Specifically, as the PEG concentration difference between the phases increased in a PEg/potassium phosphate aqueous two‐phase system, the peptide AIIP was observed to have a partition coefficient ranging from 1.2 to 1.6, AIIPAIIP from 2.4 to 5.7, AWWP from 13.5 to 32.2, and AWWPAWWP from 43 to 170. The model was extended to predict the partitioning of a staphylococcal protein A derivative (ZZ) modified with these four peptides. As predicted, the protein modified with isoleucine‐containing peptides had lower partition coefficients than the protein modified with tryptophan‐containing peptides. The partition coefficient of the ZZ protein ranged from 0.35 to 0.20, that of ZZAIIPAIIP from 0.58 to 0.48, and that of ZZAWWPAWWP from 3.5 to 5.3 in these systems. The results show that short peptide handles can significantly enhance the partitioning of proteins in aqueous two‐phase systems. The relationship between the model and the surface exposure of peptide handles and the utility of the model to aid in the design of such handles to enhance purifications are also discussed.