Stability of vitamin B-6-dependent aminotransferase activity in frozen packed erythrocytes is dependent on storage temperature.

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Hansen CM, Shultz TD

Stability of vitamin B-6-dependent aminotransferase activity in frozen packed erythrocytes is dependent on storage temperature.

J Nutr. 2001 May;131(5):1581-3.

PubMed ID

11340119 [ View in PubMed

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Abstract

Pyridoxal 5'-phosphate (PLP) stimulation of erythrocyte alanine and aspartate aminotransferase (EALT, EAST) activities is a frequently used functional measure of vitamin B-6 status. Stability of enzyme activities and activity coefficients (AC, stimulated / unstimulated) was assessed in packed erythrocytes frozen at -20, -80 degrees C and under liquid nitrogen (-196 degrees C). Activities of EALT and EAST, with and without added PLP, were determined in fresh erythrocytes (d 0) and frozen samples on d 1, 7, 14, 28, 58 and 84. In -20 degrees C samples, EALT basal activity decreased 17 and 22% (P < or = 0.05 for both) by d 58 and 84, respectively, and EAST basal activity decreased 40% (P < or = 0.05) by d 58. In -80 and -196 degrees C samples, EALT and EAST basal activities did not change significantly. Activity coefficients did not differ significantly from d 0 at any storage temperature, but EAST-AC increased 9-19% (nonsignificant) in samples stored at -20 and -80 degrees C for 7 to 84 d. Additionally, EAST-AC was significantly higher in -20 than -80 and -196 degrees C samples on d 1 and 58, respectively. Erythrocytes may be frozen for 28 d at -20 degrees C and 84 d at -80 degrees C before analysis for EALT; for EAST, activity should be measured on fresh erythrocytes.

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Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Pyridoxal phosphate	Aspartate aminotransferase, cytoplasmic	Protein	Humans	Unknown	Activator	Details