How can storage time and temperature affect enzymic activities in urines?
We measured a tubular brush-border enzyme (alanine aminopeptidase, AAP) and a lysosomal hydrolase (N-acetyl-beta-D-glucosaminidase, NAG) in morning urines from 15 healthy normal subjects to check if different storage times and temperatures could modify enzyme concentrations. Short-term (24 h) storage time at room temperature or 4 degrees C does not affect AAP and NAG activities. Both enzymes are well preserved at -70 degrees C. AAP dramatically falls after 1 month at -20 degrees C, lowering to about 8% of the initial value after only 4 days of storage. On the contrary, NAG is well preserved at these storage conditions. Centrifugation has revealed not critical for measurement of these two enzymes.
Matteucci
E
E
Cattedra di Malattie del Metabolismo, Università degli Studi di Pisa, Italia.
Gregori
G
G
Pellegrini
L
L
Navalesi
R
R
Giampietro
O
O
D000118:Acetylglucosaminidase / Q000032:analysis; D000328:Adult; D000626:Aminopeptidases / Q000032:analysis; D018826:CD13 Antigens; D004795:Enzyme Stability; D005260:Female; D005615:Freezing; D006801:Humans; D008297:Male; D013048:Specimen Handling / Q000379:methods*; D013997:Time Factors; D014556:Urine / Q000737:chemistry*
D000118:Acetylglucosaminidase; D000626:Aminopeptidases; D018826:CD13 Antigens