Publications by authors named "Simin Zaidi"

3 Publications

  • Page 1 of 1

Microbiological Control for Affinity Capture Chromatography Processing: An Industry Perspective.

PDA J Pharm Sci Technol 2018 Mar-Apr;72(2):213-221. Epub 2018 Feb 14.

BPOG

The purpose of this paper is to provide a summary of a BPOG-led industry survey of the microbiological control aspects of affinity chromatography processing in the biopharmaceutical industry. The document provides a summary of historical microbiological control concerns, coupled with industry-derived best practices, for material, equipment, and storage controls required to mitigate the potential for microbial ingress and contamination of chromatography resin and equipment. These best practice guidelines, which are derived from the members of the BPOG Bioburden Working Group, are intended to assist biopharmaceutical manufacturers to enhance microbial control and monitoring strategies for chromatography systems.
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http://dx.doi.org/10.5731/pdajpst.2017.008045DOI Listing
March 2019

Chromatographic behavior of IgM:DNA complexes.

J Chromatogr A 2011 Apr 23;1218(17):2405-12. Epub 2010 Dec 23.

Bioprocessing Technology Institute, 20 Biopolis Way, Centros, Singapore.

This study documents the presence of stable complexes between monoclonal IgM and genomic DNA in freshly harvested mammalian cell culture supernatants. 75% of the complex population elutes from size exclusion chromatography with the same retention volume as IgM. DNA comprises 24% of the complex mass, corresponding to an average of 347 base pairs per IgM molecule, distributed among fragments smaller than about 115 base pairs. Electrostatic interactions appear to provide most of the binding energy, with secondary stabilization by hydrogen bonding and metal affinity. DNA-dominant complexes are unretained by bioaffinity chromatography, while IgM-dominant complexes are retained and coelute with IgM. DNA-dominant complexes are repelled from cation exchangers, while IgM-dominant complexes are retained and partially dissociated. Partially dissociated forms elute in order of decreasing DNA content. The same pattern is observed with hydrophobic interaction chromatography. All complex compositions bind to anion exchangers and elute in order of increasing DNA content. A porous particle anion exchanger was unable to dissociate DNA from IgM. Monolithic anion exchangers, offering up to 15-fold higher charge density, achieved nearly complete complex dissociation. The charge-dense monolith surface appears to outcompete IgM for the DNA. Monoliths also exhibit more than double the IgM dynamic binding capacity of the porous particle anion exchanger, apparently due to better surface accessibility and more efficient mass transfer.
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http://dx.doi.org/10.1016/j.chroma.2010.12.066DOI Listing
April 2011

Dissociation and fractionation of heavy and light chains from IgG monoclonal antibodies.

J Chromatogr A 2011 Apr 13;1218(17):2402-4. Epub 2010 Dec 13.

Bioprocessing Technology Institute, 20 Biopolis Way, Centros, Singapore.

A basic method for dissociation and fractionation of monoclonal IgG heavy and light chain is described. It employs less noxious and hazardous reagents than the classical mercaptoethanol/propionic acid process and replaces size exclusion chromatography with cation exchange on a monolith to improve productivity. Significant scope remains to refine the conditions. The method can be applied to other disulfide bonded proteins with significant affinity for cation exchangers.
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http://dx.doi.org/10.1016/j.chroma.2010.12.008DOI Listing
April 2011
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