Effects of iron and ascorbic acid on acid phosphatases of the enamel organ of rat molars.
Protein extracts from 6- to 11-day-old rat enamel organs were applied to columns of carboxymethyl-52 cellulose. Protein eluted from the columns was assayed for acid phosphatase activity with substrates para-nitrophenylphosphate (p-NPP), beta-glycerolphosphate (beta-GP), ATP and phosphocasein. A weakly-bound peak of activity (A) emerged first which was insensitive to stimulation by iron and ascorbic acid. This enzyme hydrolysed only the phosphomonoester substrates (p-NPP and beta-GP). A strongly bound peak of activity (B) emerged later and was completely separated from the first activity. It hydrolysed all substrates except beta-GP, and was stimulated at least 10-fold by 0.1 mM ferrous ion (Fe2+) in the presence of a strong reducing agent (1.0 mM ascorbic acid). Both substances were more effective as stimulators when used together than they were when each was used separately. Dependency on these co-factors for the development of full activity increased with purification, especially when phosphocasein was substrate. The results were similar for each age of rat used. These properties of enzyme B are parallel with those of the acid phosphoprotein phosphatases of liver and spleen, and the tartrate-resistant acid phosphatase of rat bone. We conclude that enzyme B requires iron and a reducing agent for full activity and has properties that distinguishes it from the classical acid phosphatases (E.C. 3.1.3.2.).
D000135:Acid Phosphatase / Q000378:metabolism*; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D002845:Chromatography; D003746:Dental Enamel Proteins / Q000378:metabolism; D004658:Enamel Organ / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D007501:Iron / Q000494:pharmacology*; D008963:Molar; D051381:Rats; D014083:Tooth Germ / Q000201:enzymology*
D003746:Dental Enamel Proteins; D007501:Iron; D000135:Acid Phosphatase; D001205:Ascorbic Acid