Reconstitution of a purified and partially active low Km iodothyronine 5'-deiodinase with phospholipids.
We previously reported the detergent-extraction and purification to homogeneity from rat liver microsomes of an iodothyronine 5'-deiodinase which differed from the type I enzyme in its molecular size as well as its Km, thiol responsiveness, and its expected sensitivity to the antithyroid drug, propylthiouracil. The specific activity enhancement (22-fold) of the delipidated enzyme was, however, relatively modest. We report here that the purified enzyme can be activated a further 25-fold by reconstitution in microsomal phospholipids and, to a lesser extent, in soybean phospholipids. The data suggest that a native lipid environment is necessary for proper conformation of the enzyme for optimal activity.
Goswami
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Department of Medicine, Boston University School of Medicine, Massachusetts 02118.
Rosenberg
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D000818:Animals; D004789:Enzyme Activation; D007453:Iodide Peroxidase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008862:Microsomes, Liver / Q000201:enzymology*; D010743:Phospholipids / Q000737:chemistry*; D051381:Rats; D013025:Glycine max
D010743:Phospholipids; D007453:Iodide Peroxidase