Sytykiewicz Hubert, Sprawka Iwona, Czerniewicz Paweł, Sempruch Cezary, Leszczyński Bogumił, Sikora Marlena
Department of Biochemistry and Molecular Biology, Siedlce University of Natural Sciences and Humanities, Siedlce, Poland.
Acta Biochim Pol. 2013;60(3):457-65. Epub 2013 Jul 30.
Despite senescence-induced chlorophyll depletion in plants has been widely studied, the enzymatic background of this physiologically regulated process still remains highly unclear. The purpose of this study was to determine selected biochemical properties of partially purified fractions of chlorophyllase (Chlase, chlorophyll chlorophyllido-hydrolase, EC 3.1.1.14) from leaves of three Prunus species: bird cherry (Prunus padus L.), European plum (Prunus domestica L.), and sour cherry (Prunus cerasus L.). Secondarily, this report was aimed at comparing seasonal dynamics of Chlase activity and chlorophyll a (Chl a) content within investigated plant systems. Molecular weight of native Chlase F1 has been estimated at 90 kDa (bird cherry) and approximately 100 kDa (European plum and sour cherry), whereas molecular mass of Chlase F2 varied from 35 kDa (European plum) to 60 kDa (sour cherry). Furthermore, enzyme fractions possessed similar optimal pH values ranging from 7.6 to 8.0. It was found that among a broad panel of tested metal ions, Hg(+2), Fe(+2), and Cu(+2) cations showed the most pronounced inhibitory effect on the activity of Chlase. In contrast, the presence of Mg(+2) ions influenced a subtle stimulation of the enzymatic activity. Importantly, although Chlase activity was negatively correlated with the amount of Chl a in leaves of examined Prunus species, detailed comparative analyses revealed an incidental decrement of enzymatic activity in early or moderately senescing leaves. It provides evidence that foliar Chlase is not the only enzyme involved in autumnal chlorophyll breakdown and further in-depth studies elucidating this catabolic process are required.
尽管植物中衰老诱导的叶绿素消耗已得到广泛研究，但这一生理调节过程的酶学背景仍非常不清楚。本研究的目的是确定从三种李属植物叶片中部分纯化的叶绿素酶（Chlase，叶绿素叶绿素水解酶，EC 3.1.1.14）组分的某些生化特性：稠李（Prunus padus L.）、欧洲李（Prunus domestica L.）和酸樱桃（Prunus cerasus L.）。其次，本报告旨在比较所研究植物系统中叶绿素酶活性和叶绿素a（Chl a）含量的季节动态。天然叶绿素酶F1的分子量估计为90 kDa（稠李）和约100 kDa（欧洲李和酸樱桃），而叶绿素酶F2的分子量从35 kDa（欧洲李）到60 kDa（酸樱桃）不等。此外，酶组分具有相似的最佳pH值，范围为7.6至8.0。结果发现，在大量测试的金属离子中，Hg(+2)、Fe(+2)和Cu(+2)阳离子对叶绿素酶的活性表现出最明显的抑制作用。相反，Mg(+2)离子的存在对酶活性有轻微的刺激作用。重要的是，尽管在所研究的李属植物叶片中，叶绿素酶活性与Chl a含量呈负相关，但详细的比较分析显示，在早期或中度衰老的叶片中，酶活性偶尔会下降。这证明叶片中的叶绿素酶不是参与秋季叶绿素分解的唯一酶，需要进一步深入研究来阐明这一分解代谢过程。
