Abstract:

We present a method to determine concentrations of glycine between 1 and 3 mM in the simultaneous presence of 25 -lOOm M glutamate, which is a modification of the procedure originally described by Klein and Linser, Z. Physiol. Chem. 205, 251 (1932). Glycine and glutamate react with 150 m M o-phthaldialdehyde, glycine is quantitatively converted into a colored o-phthaldialdehyde-glycine-glutamate complex. By recording the absorbance of the complex at its maximum peak (around 540 nm), at 600 nm and 480 nm and applying a correction formula is possible to obtain a very good linear correlation when plotting the values of corrected absorbance versus the concentration of glycine. From these plots an extinction coefficient of 7.0 * 102 cm -1 m -1 was calculated for the complex. The method is highly reproducible and sensitive and solved the problem of glutamate interference when estimating low concentrations of glycine in mixture containing 10 to 50 times concentrations of the former aminoacid. © 1990, Walter de Gruyter. All rights reserved.