Glutamine in commercial liquid nutritional products.
Total glutamine concentrations in commercial nutritional products have been determined by enzymatic hydrolysis followed by HPLC quantification of free glutamine and free pyroglutamic acid. Hydrolysis was accomplished by a published three-enzyme (Pronase, leucine aminopeptidase, prolidase), 20-h/37 degrees C digestion. Glutamine was determined as its FMOC derivative by reverse phase HPLC-fluorescence, and pyroglutamic acid was determined directly by organic acid HPLC-UV. Approximately 4.11% of the released glutamine is converted to pyroglutamic acid during the 20-h digestion. Experimental ratios of enzyme hydrolysis glutamine to acid hydrolysis glutamic acid + glutamine + pyroglutamic acid (GLX) indicate that the method recovers >90% of the protein-bound glutamine. The nutritional products with casein dominant intact protein systems typically deliver >9 g of glutamine/100 g of protein, or approximately 40 g of glutamine/100 g of GLX.
Ross Products Division, Abbott Laboratories, 3300 Stelzer Road, Columbus, Ohio 43219, USA.
Jeffrey H
JH
Baxter
Rosalyn R
RR
Phillips
Lobat
L
Dowlati
Paul W
PW
Johns
D002851:Chromatography, High Pressure Liquid; D005526:Food, Formulated / Q000032:analysis*; D005973:Glutamine / Q000032:analysis*; D006868:Hydrolysis; D008894:Milk Proteins / Q000032:analysis; D015203:Reproducibility of Results; D012996:Solutions
D008894:Milk Proteins; D012996:Solutions; D005973:Glutamine