McKellar R C, Cholette H
J Dairy Res. 1985 Feb;52(1):91-100. doi: 10.1017/s002202990002392x.
The effect of chelating agents on extracellular proteinase production by Pseudomonas fluorescens 32A was examined. Increasing concentrations of orthophosphate slightly stimulated growth while inhibiting proteinase synthesis. Fifty per cent inhibition was found at 35 and 28 mM-orthophosphate at 5 and 20 degrees C respectively. Extracellular protein concentration was reduced by 30% when cells were grown with 100 mM-orthophosphate. Polyacrylamide gel electrophoresis of the cell-free supernatants suggested that reduced enzyme synthesis had taken place as evidenced by the decrease in staining intensity of the protein band corresponding to the proteinase. Other phosphate compounds could replace orthophosphate as an inhibitor. Extent of inhibition was related to chain length; polyphosphates with 4-6 or 13-18 phosphorus atoms were the most effective inhibitors. EDTA (0.5 mM) completely inhibited proteinase synthesis. This inhibition could be partly reversed by Ca2+ and, to a lesser extent, Mn2+. Proteinase production at 5 degrees C in skim milk was completely inhibited by phosphate glass (P13-P18). Control experiments showed that loss of activity with chelators was not due to inhibition of preformed enzyme. The results suggest a possible role for polyphosphates in controlling proteinase production in stored milk.
研究了螯合剂对荧光假单胞菌32A胞外蛋白酶产生的影响。正磷酸盐浓度增加时，生长略有刺激，但蛋白酶合成受到抑制。在5℃和20℃时，分别在35 mM和28 mM正磷酸盐时发现50%的抑制率。当细胞在100 mM正磷酸盐中生长时，胞外蛋白浓度降低了30%。对无细胞上清液进行聚丙烯酰胺凝胶电泳表明，酶合成减少，这由对应于蛋白酶的蛋白条带染色强度降低得以证明。其他磷酸盐化合物可替代正磷酸盐作为抑制剂。抑制程度与链长有关；含4 - 6个或13 - 18个磷原子的多磷酸盐是最有效的抑制剂。0.5 mM的EDTA完全抑制蛋白酶合成。这种抑制作用可被Ca2+部分逆转，在较小程度上也可被Mn2+逆转。在5℃下，脱脂乳中蛋白酶的产生被磷酸盐玻璃（P13 - P18）完全抑制。对照实验表明，螯合剂导致的活性丧失并非由于对已形成的酶的抑制。结果表明多磷酸盐在控制储存牛奶中蛋白酶产生方面可能发挥作用。
