Grigorszky I, Dévai G, Kiss K T, Tóthmérész B, Gligora M, Plenkovic-Moraj A, Kraj Koraljka, Béres V B, Schnitchen C, Borics G, Nagy A S
Department of Hydrobiology, University of Debrecen, H-4010 Debrecen, Egyetem tér 1, Hungary.
Acta Biol Hung. 2010 Mar;61(1):111-21. doi: 10.1556/ABiol.61.2010.1.11.
Phosphatase enzymes are capable of releasing phosphate through cleavage of phosphoester bonds. The seasonal importance of this process was examined by using a model substrate paranitrophenylphosphate and the Michaelis-Menten equation to estimate the release rate of PO 4 -P from phosphomonoesters. The seasonal occurrence of phosphomonoesters and acid phosphatase activity was used to estimate the velocity of phosphate release from these compounds. Filter fractionation of phosphatase activity demonstrated that most activity (>60%) was in size fractions less than 0.45 microm. The release rates were highest in May and June (15 to 25 nmol L -1 min -1 ) during the Gonyostomum semen (Raphidophyta) bloom and decreased to less than 2 nmol L -1 min -1 in two weeks and remained low throughout the summer and the fall. Fractionation of 32 P-H 3 PO 4 labelled dissolved organic phosphorus showed this fraction to vary considerably through the year. Potential phosphate release declined through the summer and into the fall. Significance of the co-occurrence of phosphomonoesters and acid phosphatase activity maxima and Gonyostomum semen (Raphidophyta) bloom is discussed.
磷酸酶能够通过磷酸酯键的断裂释放磷酸盐。利用模型底物对硝基苯磷酸酯和米氏方程来估计磷酸单酯中PO₄-P的释放速率，以此研究该过程的季节重要性。磷酸单酯和酸性磷酸酶活性的季节性出现情况被用于估计这些化合物中磷酸盐的释放速度。磷酸酶活性的滤膜分级分离表明，大部分活性（>60%）存在于尺寸小于0.45微米的级分中。在精液膝口藻（裸甲藻门）水华期间，5月和6月的释放速率最高（15至25纳摩尔·升⁻¹·分钟⁻¹），两周内降至小于2纳摩尔·升⁻¹·分钟⁻¹，并在整个夏季和秋季保持在较低水平。对³²P-H₃PO₄标记的溶解有机磷进行分级分离表明，这一级分在一年中变化很大。潜在的磷酸盐释放量在夏季和秋季逐渐下降。本文讨论了磷酸单酯与酸性磷酸酶活性最大值以及精液膝口藻（裸甲藻门）水华同时出现的意义。
