Effect of albumin on results of an "improved" analog-type assay for free thyroxin.

The paper by Sykes et al. (1) on the effect of phospholipase C on high-molecular-mass alkaline phosphatase in serum contains nomenclatural errors. In the Abstract, an Enzyme Comnussion number (EC 3.1.4.3) is given for the phospholipase C of Bacillus cereus; this is not the Enzyme Commission number of the phospholipase C responsible for the effect reported (i.e., the release of liver alkaline phosphatase from the high-Mr band). The phospholipase C responsible for this effect is a type having phosphatidylinositol specificity and its Enzyme Commission number is 3.1.4.10 (2). The phospholipase C preparation(s) from B. cereus obtained through Sigma are a mixture of phospholipases C, one being specific for phosphatidylinositol (EC 3.1.4.10), the other (EC 3.1.4.3) not (3, 4). In the introduction of the paper, the correct designation for the enzyme in question is EC 3.1.4.10, for which the recommended name is 1-phosphatidylinositol phosphodiesterase, the systematic name is 1-phosphatidyl-n-myo-inositol inositolphosphohydrolase (cyclicphosphate-forming), and an “other” name is “phosphatidylinositol phospholipase C” (2).