The Possible Significance of Hexosephosphoric Esters in Ossification

Abstract

IN the earlier papers of this series [Robison and Soames, 1924] some account was given of the properties of the phosphatase which is present in ossifying cartilage, bones and teeth, and also in the kidney and intestinal mucosa. In the following we give the results of a more detailed study of some of its properties about which further knowledge was desirable in order to understand the part played by this enzyme and by phosphoric esters in the process of ossification. OPTIMUM PH. It was previously stated that the optimum PH of this enzyme lies on a flat curve between 8-4 and 9-4, the activity being nearly constant between these limits, but falling off rapidly on either side of them. This statement was based on results of 18-hour experiments, but later observations suggested that the flattening of the curve was in part due to the gradual inactivation of the enzyme at the higher PH values and that over short periods of time the activity continues to increase with the alkalinity up to a PH well above 8-4. More exact investigation of the course of hydrolysis has shown that these suppositions are correct. Fig. 1 shows the rate of hydrolysis of glycerophosphoric ester over a period of 5 hours at pH between 7.25 and 9-4. Further measurements, not shown on the chart, were taken at the end of 24, 48 and 166 hours. The PH was determined from time to time by a micro-colorimetric method (capillator) on 002 cc. liquid withdrawn from the reacting mixture. The addition of indicators to the bulk of the liquid was inadmissible on account of the subsequent colorimetric estimations of inorganic phosphate (Briggs). In this experiment the initial rate increased with the alkalinity up to 9 4, the highest PH attempted, but at the end of 24 hours the amount

Comparative Biochemical Studies on Normal and on Poliomyelitis Virus-Infected Tissue Cultures

“…4. Effect of long incubation on phosphomonoesterase in TC with both enzymes (at pH 5 and 10.9 respectively) and may be due to the inactivation of the phosphatase as effect of pH (33). Assays of long term incubation also gave comparable results but the rate of alkaline phosphatase activity was markedly reduced in normal 14 day old cultures.…”

“…The inhibition may be the primary change and precedes the visible CPE for days, depending on the size of inoculum. Any phosphatase method (16,18,34,33) could be adopted for the purpose of measuring enzyme activities in roller tubes or large production bottles (15).…”

Mechanism of Mineralization of Collagen‐Based Connective Tissues

“…This fact was first recognized in the 1920s when Martland and Robison stated that the function of alkaline phosphatase was to increase the local phosphate concentration [59]. Later in the 1970s Binderman et al found that elevating phosphate levels was sufficient to convert a non-mineralizing differentiating mesenchymal cell culture that formed cartilage into one that formed calcified cartilage [60].…”

Biochemistry meets biology: Key findings for bone calcification and a lifetime philosophy of collaboration

“…of investigations on the isolation, the mode-of-action and the distribution of phosphoric esterases in different tissues [4][5][6][7][8][9][10][11][12][13] .…”