Biomedical subjects

D W Province

Publications and source records attributed to D W Province.

5 recordsLinked to original sources

PubMed1999

Algorithms for validating chiral properties of insulins.

The combination of chiral ligand exchange on Cu(II) complexes in aqueous base with circular dichroism spectropolarimetric detection provides excellent avenues to validate the chirality properties of oligopeptides and proteins. The method is quick and simple and has the potential for development into an automated, routine procedure for quality control applications. Target analytes used for this first study of a protein system are human, porcine, and bovine insulins prepared by different procedures and obtained from different sources, production lots, and manufacturers. The analytical specificity of the test makes the method a potentially useful technique for validating the chirality properties of many peptide and protein forms.

Algorithms↗

PubMed1999

Algorithms for the quantitative validation of chiral properties of peptides.

Complexation with Cu(II) ion in strong aqueous base, combined with visible range circular dichroism detection, were used to quantitatively differentiate among the L-enantiomers of the GG, GA, GY, AG, AA, AY, YG, YA, and YY dipeptides and the D-enantiomer of GA. Using ellipticity data at all (n = 1500) wavelengths in the measured spectra, and two novel data reduction procedures, quantitative determinations were made of the compositions of binary mixtures. For mixtures made with the L-GA and D-GA enantiomers, the accuracy of the measured enantiomeric purities was better than 0.17 % over the 1-48 % range for the minor component. The method has considerable potential for use in quality control of peptide and protein biotechnological drug forms.

Algorithms↗

PubMed1999

Tripeptide discriminations using circular dichroism detection.

A general spectroscopic method is described that might be applied to validating amino acid sequences in peptides and protein fragments with a view to it becoming a routine procedure with which to characterize biotechnology drug products. The tripeptides are the L-enantiomers of GGA, GGH, GGI, GGL, GGF, GHG, LGG, and YGG. The simple procedure calls for their complexation with Cu(II) ion in strong aqueous base. Binding the first three residues in the sequence, beginning at the amine terminus, completes the coordination sphere of the Cu(II) ion, so duplication of the initial sequence from peptide to peptide could be an important limiting factor in determining the extent of differentiation that is possible. The analytical focus is the selectivity associated with the chirality properties of the peptides. Detection is by circular dichroism operating in the visible range. The eight analytes were chosen as representative of a series where the sequences are most similar and therefore potentially the most difficult to discriminate spectroscopically. All have just one chiral center. Using ellipticity data at all (n = 1500) wavelengths in the measured spectra, and two novel data reduction procedures, total discrimination among all eight analytes is achieved. The method has considerable potential for use in quality control of peptide and protein biotechnological drug forms, especially their enantiomeric purities.

Algorithms↗

PubMed1999

A convenient assay method for the quality control of peptides and proteins.

The development of a convenient and very accurate procedure with which to discriminate among subsets of structurally similar peptides and proteins, and measure enantiomeric purities with very good accuracy, has been described in a series of recent articles. A factor preventing its general application to all peptide forms is that comparisons were originally limited to closed subsets of structurally similar types, e.g., dipeptides, tripeptides, and insulin drug forms. In the most recent of these articles, a modification to the method was described which did enable the comparisons to be extended between sets, in particular the di-and tripeptides. That same modification is extended even further in this article to include additional di- and tripeptides, glycylglycine oligomers, insulin drug forms, and neuropeptides. The same principal component analysis treatment used for data reduction and statistical comparisons in prior work enables the discrimination among 49 of the total of 51 analytes investigated.

Circular Dichroism↗

PubMed1999

Clustering of CD spectral data as a prototype QSAR model for neuropeptides.

An analytical method that might eventually qualify as a general quality control assay procedure for polypeptide drug forms was described in the companion article to this paper. The detector is visible range circular dichroism spectroscopy. Multivariate data analysis reduced the spectral data to essentially four principal components (or factors) that are characteristic of each analyte. The level of analytical selectivity achieved among 51 analytes is very high. Using an alternative factor analysis algorithm, the selectivity is even more conveniently accomplished in the form of a 2-D cluster diagram presentation that has the potential of being a prototypical predictive in vitro model for correlating experimental data with structure-activity or structure-function relationships. Clustering of the analytes is a consequence not only of the chiral interactions associated with ligand exchange in the immediate primary coordination sphere of the host derivatizing reagent, but also of long-range intermolecular interactions between the coordination architecture of the host and the chiral polypeptides.

Circular Dichroism↗