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PROTEIN-BASED SELECTORS

Protein-Based Selectors

The portfolio of the Daicel chiral stationary phases is well complemented by adding chiral protein-based stationary phases (PSPs): CHIRALPAK® AGP, CHIRALPAK HSA and CHIRALPAK CBH. Our immobilized PSPs are successfully utilized by scientists for separation and characterization of chiral compounds in a great number of applications, ranging from drug discovery and quality assurance of marketed drugs to environmental monitoring.

The chiral selector for the CHIRALPAK AGP is α1-acid glycoprotein (AGP), while human serum albumin (HSA) is the chiral selector for CHIRALPAK HSA. The chiral selector for CHIRALPAK CBH is cellobiohydrolase, a stable enzyme. These three chiral selectors are immobilized on 5-µm spherical silica particles. The PSPs function entirely in the reversed-phase chromatographic mode, using buffers with low organic modifier content and at moderate pH values.

Protein-based stationary phases were originally developed and manufactured by ChromTech Ltd., U.K. Chiral Technologies Europe acquired ChromTech in 2009, and Chiral Technologies is now the only manufacturer of these widely recognized PSPs and columns.

The CHIRALPAK AGP selector has extremely broad applicability for the separation of chiral compounds. One of the reasons is that its chiral bonding properties can be changed dynamically. CHIRALPAK HSA is used to separate acidic compounds directly – without derivatization prior to analysis – and also nonprotolytic compounds. The CHIRALPAK CBH selector is an effective complement to CHIRALPAK AGP for separation of basic compounds. A large variety of chiral compounds can be separated using the PSPs.

Enantioselectivity

Enantioselectivity can easily be controlled or improved by changes in the mobile phase composition: pH, buffer and organic modifier types and concentrations. The mobile phases, with which these columns are used, are compatible with MS and MS/MS analyses.

To view guidelines on method development for the PSP columns, click here.

Generic Drug Analysis

The PSP columns are successfully applied to enantiomeric purity analyses of bulk drugs and also of finished drug formulations. The United States Pharmacopeia (USP), the widely used and continuously revised compendium of standardized test methods, lists the CHIRALPAK AGP brand of L41 column for HPLC methods to test Enantiomeric Purity of the single-enantiomer drugs.

Chiral Technologies Generic Drug Analysis USP table

GENERIC DRUG ANALYSIS USP TABLE

Download the
USP table

Drug-Protein Binding

An exciting area of applications of the protein stationary phases, specifically the CHIRALPAK HSA, is their use in drug-protein binding studies.

Proteins found in plasma are responsible for many bodily processes such as the transport, distribution, metabolism and excretion of different molecules. Therefore, it is vital to characterize binding properties between drug molecules and plasma proteins. Drug-protein binding is the reversible interaction of drugs with proteins in plasma. The degree of drug-protein binding directly affects pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of a drug. Drug potency, therefore, is dependent on the degree of drug interactions with plasma proteins and other blood constituents. One of the major blood proteins to which drugs bind is human serum albumin. Understandably, the unbound drug is active and exhibits pharmacologic effects. Rational selection of new drug targets is time and resource consuming; therefore, better prediction on drug efficacy and safety is vital to support timely go/no-go decisions on which drug candidate to move to clinical trials.

Although a number of methods are available to measure the degree of the drug interactions with proteins in plasma, HPLC is also a convenient and fast way to determine the drug-protein binding properties. Both CHIRALPAK HSA and CHIRALPAK AGP have been successfully used in drug-binding studies. A lecture on the Application of Bio-mimetic HPLC for Protein Binding Measurements in Drug Discovery was presented by Dr. Klara Valko of GSK at Physchem Forum 2010.

Chiral Technologies CHIRALPAK HSA for drug-binding studies

CHIRALPAK HSA For Drug-Binding Studies

Download a PDF of the presentation

Columns, containing chiral selectors for species other than human such as rat and dog albumins, are also available.

Please see the Product List for additional information.

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