Lambers J W, Terpstra W
Biochim Biophys Acta. 1985 Oct 4;831(2):225-35. doi: 10.1016/0167-4838(85)90039-1.
Chlorophyllide combines spontaneously not only with phosphatidylcholine (PC) liposomes but also with various other (plant) lipids dispersed in an aqueous medium. The lipid-associated chlorophyllide is highly fluorescent and the fluorescence yield is virtually independent of the nature of the lipid. Chlorophyllase (chlorophyll chlorophyllidohydrolase, EC 3.1.1.14) activity assays that are based on the determination of this chlorophyllide fluorescence show that phosphatidylglycerol (PG), and also sulphoquinovosyldiacylglycerol (SQDG), associate with isolated chlorophyllase, thereby inactivating the enzyme in a co-operative way. The extent of this inactivation depends on the pH and ionic strength of the reaction medium and can be completely reversed by divalent cations (Mg2+). The inhibition of chlorophyllase effected by free PG liposomes can be counteracted by electrically neutral lipids at relatively high concentration (PC and also chloroplast lipids). Digalactosyldiacylglycerol (DGDG) is not effective in this respect. When PG has been incorporated in PC or DGDG liposomes, its ability to inhibit chlorophyllase activity is reduced. Whereas the remaining chlorophyllase-inactivating effect of PG, incorporated in PC, can still be reversed by Mg2+, this is not found when enzyme inactivation is caused by PG incorporated in DGDG. The results reported here are consistent with those obtained earlier concerning the stabilization of chlorophyllase by PG and PG/galactolipid mixtures (Lambers, J.W.J., Verkleij, A.J. and Terpstra, W. (1984) Biochim. Biophys. Acta 786, 1-8). They are discussed in terms of the regulation of chlorophyllase activity by lipids surrounding the enzyme and by divalent cations.
叶绿素酸不仅能自发地与磷脂酰胆碱（PC）脂质体结合，还能与分散在水介质中的各种其他（植物）脂质结合。与脂质结合的叶绿素酸具有很强的荧光性，且荧光产率几乎与脂质的性质无关。基于这种叶绿素酸荧光测定的叶绿素酶（叶绿素叶绿素酸水解酶，EC 3.1.1.14）活性测定表明，磷脂酰甘油（PG）以及硫代异鼠李糖基二酰基甘油（SQDG）与分离出的叶绿素酶结合，从而以协同方式使该酶失活。这种失活的程度取决于反应介质的pH值和离子强度，并且可以被二价阳离子（Mg2+）完全逆转。游离的PG脂质体对叶绿素酶的抑制作用可以被相对高浓度的电中性脂质（PC以及叶绿体脂质）抵消。在这方面，二半乳糖基二酰基甘油（DGDG）无效。当PG被掺入PC或DGDG脂质体中时，其抑制叶绿素酶活性的能力会降低。虽然掺入PC中的PG对叶绿素酶的剩余失活作用仍可被Mg2+逆转，但当酶失活是由掺入DGDG中的PG引起时，情况并非如此。这里报道的结果与早期关于PG和PG/半乳糖脂混合物对叶绿素酶稳定性的研究结果一致（Lambers, J.W.J., Verkleij, A.J.和Terpstra, W.（1984年）《生物化学与生物物理学报》786, 1 - 8）。从围绕酶的脂质和二价阳离子对叶绿素酶活性的调节方面对这些结果进行了讨论。
