title: Long-term stability of enzymes in human serum stored in liquid nitrogen.
abstract: We analyzed the stability of the enzymes alpha-amylase (EC 3.2.1.1), alkaline phosphatase (EC 3.1.3.1), alanine aminotransferase (EC 2.6.1.2), aspartate aminotransferase (EC 2.6.1.1), creatine kinase (EC 2.7.3.2), glutamate dehydrogenase (EC 1.4.1.3), gamma-glutamyltransferase (EC 2.3.2.2) and lactate dehydrogenase (EC 1.1.1.27) of a human serum pool during storage in liquid nitrogen for a period of 10 months. Except amylase and creatine kinase, all enzymes were stable. Amylase increased in activity, creatine kinase activity decreased. Therefore, human serum stored at -196 degrees C can be used as satisfactory substitute for lyophilized enzyme control serum in internal quality control and stable enzyme material for optimization of methods.
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000469:Alkaline Phosphatase / Q000097:blood; D001219:Aspartate Aminotransferases / Q000097:blood; D001793:Blood Preservation; D003402:Creatine Kinase / Q000097:blood; D004798:Enzymes / Q000097:blood*; D005615:Freezing; D005969:Glutamate Dehydrogenase / Q000097:blood; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D009584:Nitrogen; D012015:Reference Standards; D000516:alpha-Amylases / Q000097:blood; D005723:gamma-Glutamyltransferase / Q000097:blood
chemical_list: D004798:Enzymes; D007770:L-Lactate Dehydrogenase; D005969:Glutamate Dehydrogenase; D005723:gamma-Glutamyltransferase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D003402:Creatine Kinase; D000469:Alkaline Phosphatase; D000516:alpha-Amylases; D009584:Nitrogen