Tramadol is a potent analgesic drug which interacts with mu-opioid and has low effect on other opioid
receptors. Unlike other opioids, it has no clinically significant effect on respiratory or cardiovascular parameters.
Alakaline phosphatase is a hydrolase enzyme that prefers alkaline condition and removes phosphate group from different
substrates. In this study, the interaction between tramadol and calf liver alkaline phosphatase was investigated. The results
showed that tramadol can bind to alakaline phosphatase and inhibit the enzyme in an un-competitive manner. Ki and IC50
values of tramadol were determined as about 91 and 92 μM, respectively. After enzyme purification, structural changes on
alakaline phosphatase-drug interaction were studied by circular dichroism and fluorescence measurement. These data
revealed the alteration in the content of secondary structures and also conformational changes in enzyme occurred when
the drug bound to enzyme-substrate complex.