Some cells such as tumors and spleen cells appear to have only the acidic isozyme while muscle rich tissues exhibit only the basic form. The liver appears to have both isozymes in equal amounts. The enzyme is kinetically complex in that three substrates and products are involved and the rate of catalysis of the basic form is modified by divalent metal ions. Several natural antibodies and some therapeutics specifically inhibit this enzyme. These features make it an important enzyme to research.
Several projects are now open for investigation.
Enough enzyme has been purified from rat muscle and other sources to investigate the kinetics of the enzyme and to begin crystallographic investigations but further studies require larger amounts of protein than is economically feasible to obtain from tissues. Our laboratory would like to insert the sequence into an expression vector for E.coli and a eukaryotic system. The E.coli system would supply the capacity to make large amounts of AdSS but there is some indication that post-translational modification may be necessary. Expression in a eukaryotic system may be necessary for production and at least will allow a comparison of the enzyme expressed in the two different systems. Other research projects include screening other organisms to see if two isozymes are used in other species and to further characterize the enzyme itself.