Determination Of L-glutamine Research Articles

A novel glutamine biosensor based on zinc oxide nanorod and glutaminase enzyme from Hypocria jecorina

A novel biosensor for determination of L-glutamine in pharmaceutical glutamine powder was developed via immobilizing our produced glutaminase enzyme from Hypocria jecorina onto our prepared zinc oxide (ZnO) nanorod and chitosan. ZnO nanorods were prepared as surface-dependent and surface-independent and both were used. The biosensor is specific for L-glutamine and the peculiar analytical properties (linearity range, reproducibility, and accuracy) of it were experimentally determined. The optimum operating conditions of the biosensor such as buffer concentration, buffer pH, and medium temperature effect on the response of biosensor were studied. Km and Vmax values for the our-producing glutaminase enzyme from Hypocria jecorina immobilized on the biosensor were also determined as 0.29 mM and 208.33 mV/min., respectively, from Lineweaver–Burk plot. The biosensor was then used for the determination of glutamine contained in pharmaceutical formulations.

Determination of ammonium and L-glutamine in hybridoma cell cultures by sequential flow injection analysis.

A flow injection analytical system based on a gas diffusion membrane module for ammonia and an ammonium flow-through potentiometric detector has been set up for measurement of L-glutamine and ammonium ions in hybridoma cell cultures. The main feature of the system is that the same basic analytical concept and equipment is used in both measurements, the only difference being for the determination of L-glutamine, in which the sample flows through an immobilized glutaminase cartridge. The conditions to enable the performance of both analysis consecutively, avoiding potential interferences by unwanted deamination of other compounds in the samples, have been determined. Finally, the proposed system has been compared with reference analytical methods for batch hybridoma cell culture experiments.

Simultaneous enzymatic/electrochemical determination of glucose and L‐glutamine in hybridoma media by flow‐injection analysis.

A split-stream flow-injection analysis system is described for simultaneous determination of glucose and L-glutamine in serum-free hybridoma bioprocesses media. Amperometric measurement of glucose is based on anodic oxidation of hydrogen peroxide produced by immobilized glucose oxidase within a triple layer membrane of an integrated flow-through glucose-selective biosensor. Determination of L-glutamine is based on quantitating ammonium ions produced in a flow-through enzymes reactor containing immobilized glutaminase enzyme, and subsequent downstream potentiometric detection of these ions by a nonacting-based ion-selective polymer membrane electrode. Endogenous potassium and ammonium ion interference in the L-glutamine determination are eliminated by using a novel in-line tubular cation-exchange membrane unit to exchange these interferent species for cations undetectable by the membrane electrode. The first generation split-steam flow-injections system can assay 12 samples/h using direct injections of 50 microL of media samples, with linear responses to glucose in the range of 0.03 to 30 mM, and log-linear response to L-glutamine from 0.1 to 10 mM.

Simultaneous determination of ammonia nitrogen and L-glutamine in bioreactor media using flow injection.

A novel split stream flow injection (FI) system suitable for the simultaneous determination of L-glutamine and ammonia nitrogen (ammonia-N) in cell culture media is described. Potentiometric detection of ammonia-N in one portion of the manifold is achieved using a commercial ammonia gas-sensing electrode fitted with a wall-jet cap. L-Glutamine is quantified in the other part of the split sample by potentiometric detection of ammonium ions (by an ammonium-selective polymer membrane electrode), liberated from the hydrolysis of glutamine after the sample flows through a glass bead reactor containing immobilized glutaminase. Endogenous ammonia-N and potassium ions that would normally interfere with the glutamine measurement are removed upstream using a unique tubular cation-exchange unit. Using 50 microliters sample volumes and mixed solutions of ammonium chloride and L-glutamine in Iscove's Modified Dulbecco's Medium to calibrate the FI measuring system, values for ammonia-N and L-glutamine determined for 22 media samples obtained from a bioreactor growing retroviral producer cells correlate well with those measured with commercial, manual enzymic-spectrophotometric assay kits.

Determination of l-glutamine in preparation using high-performance liquid chromatography

Determination of l-glutamine in preparation using high-performance liquid chromatography