Thermostability of purified human pancreatic α-amylase is increased by the combination of Ca 2+ and human serum albumin

• Published in: Clinica chimica acta Vol. 252; no. 1; pp. 11 - 20
• Main Authors: Tessier, Arthur J., Dombi, George W., Bouwman, David L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1996
• Subjects: Alpha-amylase; Amylases; Calcium; Kinetics; Metalloproteins; Serum albumin; Thermodynamics; Alpha-amylase; Thermodynamics; Amylases; Calcium; Serum albumin; Kinetics; Metalloproteins
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/0009-8981(96)06316-4

Pancreatic fluid from a patient with a post operative pancreatic fistula was used to isolate human α-amylase by means of acarbose affinity chromatography. Amylase thermostability was measured in 4 solutions: (1) EDTA-dialyzed; (2) dialyzed solution plus 0.15 mmol/1 (1.0 g/dl) human serum albumin; (3) dialyzed solution plus 0.25 mmol/1 (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°C. Thermostability was characterized by t 1 2 , the time to 50% initial amylase enzyme activity. In the dialyzed solution t 1 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 t 1 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.