Griebel R J, Merrick J M
J Bacteriol. 1971 Nov;108(2):782-9. doi: 10.1128/jb.108.2.782-789.1971.
Mild alkaline extraction of native poly-beta-hydroxybutyrate (PHB) granules results in the solubilization of a protein fraction. Both the solubilized protein fraction and the extracted granules are essentially devoid of PHB synthetase activity unless recombined. The protein fraction has been separated by chromatography into two components (A-I and A-II). A-I but not A-II can be recombined with extracted granules to give rise to PHB synthetase activity. Extracted granules no longer require pretreatment with activator or trypsin but are directly susceptible to hydrolysis by Rhodospirillum rubrum depolymerase. Addition of A-II or A-I prevents the direct hydrolysis by depolymerase. The inhibition is reversed by activator or trypsin. We conclude that native granules are associated with a protein inhibitor which prevents the hydrolysis of PHB by depolymerase unless the protein is destroyed by trypsin, removed by alkaline extraction, or modified by activator.
用温和的碱性方法提取天然聚-β-羟基丁酸酯（PHB）颗粒会导致一种蛋白质组分溶解。溶解的蛋白质组分和提取的颗粒基本上都没有PHB合成酶活性，除非重新组合。通过色谱法将蛋白质组分分离为两个组分（A-I和A-II）。A-I而非A-II可以与提取的颗粒重新组合以产生PHB合成酶活性。提取的颗粒不再需要用激活剂或胰蛋白酶进行预处理，而是直接易受红螺菌解聚酶的水解作用。添加A-II或A-I可防止解聚酶的直接水解作用。激活剂或胰蛋白酶可逆转这种抑制作用。我们得出结论，天然颗粒与一种蛋白质抑制剂相关联，该抑制剂可防止解聚酶对PHB的水解作用，除非该蛋白质被胰蛋白酶破坏、通过碱性提取去除或被激活剂修饰。
