High resolution high-performance liquid chromatography separation of polyglutamic acids.

Poly-L-glutamic acids can exist in random coil, ibility because of its poor pH stability and organic helix, or sheet depending on the environmental conditions. Therefore, they have been used as molecular models for a better understanding of macromolecular stereochemistry [1]. Polyglutamylation is also the major posttranslational modiWcation of neuronal tubulin [2,3], and foliates are polyglutamylated in most organisms, with pentaglutamates being the predominant forms of foliate polyglutamylation in a number of species [4]. Poly-L-glutamic acids were also found to be related to a variety of biological functions such as the enhancement of the transgene expression for plasmids [5] and the preferential delivering of paclitaxel [6,7], a widely used anticancer agent, to tumor sites, thereby improving its eVectiveness and reducing its toxicity. Polyglutamic acids are highly charged in physiological pH solution. Many of the properties of polyglutamic acids in solution vary considerably with molecular weight. The accurate determination of molecular weights and the molecular weight distribution of polyglutamic acids used in chemical and biochemical experiments are essential. The methods for the estimation of the range of the molecular weight and the molecular weight distribution of polyglutamic acids were mainly based on viscometry and light-scattering determination. An improvement in accuracy was achieved with the introduction of size exclusion chromatography combined with online diVerential viscometer, diVerential refractometer, and light-scattering detectors [8]. The separation of oligomers of glutamic acid was also achieved by high-performance liquid chromatography (HPLC) using RPC-5 chromatography [9]. However, RPC-5 chromatography suVered from poor reproduc-