Genentech, Inc.

Indiana University

Liangyi Zhang

Thomas W Patapoff

Yajun Wang

Boyan Zhang

Dell Farnan

George Tony Moreno

James P Reilly

The present invention provides methods for analyzing compositions of polypeptides such as antibodies by ionic strength-mediated pH gradient ion exchange chromatography. In some aspects, the methods use a combination of pH gradients and ionic strength gradients to separate the polypeptide from charge variants of the polypeptide. In some aspects, the methods use a stable ionic strength to optimize the pH gradient separation window to separate the polypeptide from charge variants. Such methods are useful for analyzing polypeptide, e.g. antibodies, with a pI greater than 9 or a pI less than 7. In some aspects, the invention provides a multiproduct method for the analysis of polypeptides of varying pI's.

Ionic strength-mediated pH gradient ion exchange chromatography

Methods of identifying polypeptides have been developed using a de novo sequencing technique. Methods use photodissociation and low-energy fragmentation and the spectra of peptide ions obtained therefrom, such as obtained by post-source decay (PSD), have been developed. The methods include photodissociation and the spectra therefrom obtainable from treating ions with predetermined wavelengths of radiation in the vacuum ultraviolet range of the electromagnetic spectrum. The confidence of amino acid assignments based on x-type ions is evaluated by observing complementary y-, v- and w-type ions that provide additional constraints to sequence identification.

Method of identifying peptides

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South San Francisco, CA, United States of America

Liangyi Zhang