Alkaline phosphatase factors affecting

Several assays, such as the ultra-sensitive luminescent ELRA developed by Seifert (2004) with a detection limit of 20 ng L-1 for 17 (3-estradiol, have been reported in the literature. Although these assays are simple to use, many factors, such as differences in culture conditions, cell density or cell-line clones, affect the potency of estrogenic substances, and that makes the standardization of these methods difficult. The induction of several proteins or enzyme activities (e.g. the increasing levels of alkaline phosphatase, cathepsin D, prolactin and vitellogenin as a consequence of progestogens) has also been used to study estrogenicity. However, expression of these proteins or enzyme activities is restricted to specific cell lines and cannot be extrapolated to other tissues or species. 

Markert and Frei have reviewed Biochemical Events Related to Phagocytosing Cells. The clinical chemist is required more and more to deal with isolation and measurement of components in leukocytes. These authors have considered the techniques for isolation of the cells and their subcellular components as well as the biochemical mechanisms involved in phagocytosis in both normal and pathological situations. Alkaline phosphatase has been of considerable interest to clinical chemists for more than 50 years Posen and Doherty have reviewed The Measurement of Serum Alkaline Phosphatase in Clinical Medicine and, in a detailed fashion, have outlined available information regarding the significance of serum alkaline phosphatase in a variety of disease states as well as the many physiological and analytical factors affecting the activity of this enzyme. 

The added substrate should meet two requirements the released product should be easy to detect and the chemical nature of the substrate (i.e. the stability of the bond to be cleaved) should be comparable with that of the available natural substrate. The effects of temperature, pH and possible inhibitors should be taken into account. Petterson and Jansson (1978) tested the activity of enzymes derived from freshwaters in comparison with commercially available alkaline phosphatases using different artificial substrates and found that the factors affecting the results included temperature, pH and phosphate concentration. 

Hernandez, I., Christmas, M., Yelloly, j.M. and Whitton, B.A. (1997) Factors affecting surface alkaline phosphatase activity in the brown alga Fucus spiralis L. studies at a North Sea intertidal site (Tyne Sands, Scotland), youma/ of Phycology 33, 559-575. 

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