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.
Cattedra di Malattie del Metabolismo, Università degli Studi di Pisa, Italia.
E
E
Matteucci
G
G
Gregori
L
L
Pellegrini
R
R
Navalesi
O
O
Giampietro
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