Thermostability of purified human pancreatic alpha-amylase is increased by the combination of Ca2+ and human serum albumin.
Pancreatic fluid from a patient with a post operative pancreatic fistula was used to isolate human alpha-amylase by means of acarbose affinity chromatography. Amylase thermostability was measured in 4 solutions: (1) EDTA-dialyzed; (2) dialyzed solution plus 0.15 mmol/l (1.0 g/dl) human serum albumin; (3) dialyzed solution plus 0.25 mmol/l (1.0 mg/dl) calcium ions; and (4) dialyzed solution with both human serum albumin and calcium ions. Amylase activity was measured at predetermined times in samples heated to 60 degrees C. Thermostability was characterized by t1/2, the time to 50% initial amylase enzyme activity. In the dialyzed solution t1/2 was 0.75 +/- 0.19 min. This rose to 1.62 +/- 0.34 min with added human serum albumin, and to 8.24 +/- 0.13 min with added calcium ions. The combination of human serum albumin and calcium ions resulted in a synergistic increase of t1/2 to 180 +/- 26 min. These findings support our contention that human serum albumin, calcium ions and possibly other body fluid constituents must be considered in any utility involving amylase thermostability as a clinically relevant diagnostic marker.
Tessier
A J
AJ
Harper Hospital, Department of Surgery, Detroit, MI 48201, USA. atessie/cms.cc.wayne.edu
Dombi
G W
GW
Bouwman
D L
DL
D002118:Calcium / Q000378:metabolism*; D004795:Enzyme Stability; D006207:Half-Life; D006358:Hot Temperature; D006801:Humans; D010179:Pancreas / Q000201:enzymology*; D012709:Serum Albumin / Q000378:metabolism*; D000516:alpha-Amylases / Q000378:metabolism*
D012709:Serum Albumin; D000516:alpha-Amylases; D002118:Calcium