Human liver multiple molecular forms

The purification of acid phosphatase from the human liver and the description of its properties do not appear to have been accomplished. Partly, this may be due to the inherent difiBculty of obtaining normal, fresh human material in amounts substantial enough for purification. However, because of the cellular and physiological importance of acid phosphatase, it is advisable to describe in the present section the purifications of the enzyme from rat and bovine liver. Moreover, since these purifications were accomplished with the awareness that acid phosphatase from this source might be present in multiple molecular forms, the descriptions will naturally involve a consideration of the isoenzymes and their properties. 

This order of evaluation (biochemical, first starch gel, second) is amply justified from our own experiences and the consensus of opinion at a recent symposium on multiple molecular forms of enzymes. In particular, heterogeneity of human intestinal alkaline phosphatase on starch gel was reported by Moss (M34) and Fishman and Kreisher (F9, K25). A certain amount of LPSAP intestinal enzyme may occupy the same position that liver alkaline phosphatase migrates to. On the other hand, more than one band in nonliver positions can be produced by intestine. Another similar situation is seen with placental alkaline phosphatase, which may show three bands. Consequently, the starch-gel data can be correlated with biochemical studies only if the nature and organ source of the preparation are known in advance. 

There are several reports by Jones and co-workers dealing with the purification, properties and conformation of the orotate phosphoribosyltransferase and orotidylic acid decarboxylase enzyme complex present in mouse Ehrlich ascites cells [135-137]. Multiple molecular forms of orotidylic acid decarboxylase from human erythrocytes and human liver were studied by O Sullivan and co-workers [138,139]. A bifunctional enzyme complex of orotate phosphoribosyltransferase and orotidylic acid decarboxylase occurs also in mouse liver and brain [140], regardless of the developmental stage of the animal. Both enzyme activities remained co-ordinate in fetal, neonatal, immature and adult liver and brain. 

C6 Campbell, M. T., Gallagher, N. D. and O Sullivan, W. J. Multiple molecular forms of orotidylate decarboxylase from human liver. Biochem. Med., 17, 128-140 (1977)... 

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