R . Van Heyningen and a . Pirie

Pirie, van Heyningen & Flanders (1955) showed that the concentrations of certain acid-soluble phosphates in the lens, when estimated by the enzymic method of Slater (1953), were much lower than the concentrations reported by Nordmann & Mandel (1952), who used the barium-fractionation method of LePage (1948, 1949). This method has, until recently, been the accepted and standard one for estimation ofacid-soluble phosphates. Using the enzymic method we found large deficits in creatine phosphate, hexose phosphates and phosphoglyceric acid. It seemed doubtful whether creatine phosphate was present in measurable quantity and the sum of the hexose phosphates and phosphoglyceric acid amounted to only 12-40 pmoles of P/100 g. of lens when estimated enzymically, whereas the chemical estimation had given about 400 ,umoles of P/100 g. of lens in this form. Similar discrepancies were found in the analyses of the acid-soluble phosphates of rat kidney and liver, but not of those of rat muscle, where enzymic and chemical analyses agreed. LePage's analysis of the rat muscle has also been confirmed recently by Threlfall (1957), using a method based on chromatography. The enzymic method can claim greater specificity than the chemical one and it seemed likely that it gave truer values. This implied that the nature of a considerable part of the organic acid-soluble phosphates of lens and of other tissues was still unknown. We have therefore analysed the acidsoluble phosphates of lens by chromatographic and other methods in an attempt to identify further substances and narrow the gap between total phosphorus and the phosphorus in known compounds. The analysis which we report has not uncovered any compound not already known in other tissues but it has radically altered our conception of acidsoluble phosphates in the lens, and this may make necessary a reorientation of views of lens metabolism. We have examined the lens of both rabbit and ox.