N-METHYL MESOPORPHYRIN-IX INHIBITS PHYCOCYANIN, BUT NOT CHLOROPHYLL SYNTHESIS IN CYANIDIUM-CALDARIUM
N-METHYL MESOPORPHYRIN-IX INHIBITS PHYCOCYANIN, BUT NOT CHLOROPHYLL SYNTHESIS IN CYANIDIUM-CALDARIUM
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DOI：
10.1104/pp.71.2.263
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发表时间：
1983-01-01
期刊：
影响因子：
7.4
通讯作者：
CHEN, NC
中科院分区：
文献类型：
--
作者：
BEALE, SI;CHEN, NC
利用N-甲基中卟啉IX（NMMP）通过特异性抑制酶促Fe插入原卟啉IX来阻断血红素合成的能力来测试血红素是否是藻蓝蛋白（PC）的胆色素发色团的前体。一株单细胞红藻C.在黑暗中形成正常量的叶绿素（Chl）和PC的高温箱被用来避免外源卟啉的光毒性效应。相对叶绿素和PC含量测定全细胞悬浮液。当细胞在黑暗中在基于葡萄糖的异养培养基上在42 ℃下生长时，C时，NMMP对分裂速率和Chl合成均无影响，直至3.0 μ M和长达72小时。NMMP对PC合成具有剂量依赖性抑制作用。在用0.3、1.0、3.0和10.0 μ M NMMP生长48小时的细胞中，相对于对照细胞值，PC与Chl的吸光度比分别为100%、89%、86%和50%。NMMP还引起细胞内原卟啉的积累。NMMP的能力，导致细胞间积累的原卟啉和阻止PC的合成，同时允许正常的叶绿素的形成是一致的，这一行动作为一个特定的抑制剂酶铁螯合和支持血红素的作用作为前体的藻胆素。
The ability of N-methyl mesoporphyrin IX (NMMP) to block heme synthesis by specifically inhibiting enzymic Fe insertion into protoporphrin IX was exploited to test whether heme is a precursor of the bilin chromophore of phycocyanin (PC). A strain of the unicellular rhodophyte C. caldarium which forms normal amounts of chlorophyll (Chl) and PC in the dark was employed to avoid phototoxic effects of exogenous porphyrins. Relative Chl and PC content were assayed spectrophotometrically on whole cell suspensions. When cells were grown in the dark on a glucose-based heterotrophic medium at 42.degree. C, neither division rate nor Chl synthesis was affected by NMMP up to 3.0 .mu.M and for as long as 72 h. NMMP had a dose-dependent inhibitory effect on PC synthesis. PC to Chl absorbance ratios, relative to control cell values, were 100%, 89%, 86% and 50% in cells grown for 48 h with 0.3, 1.0, 3.0 and 10.0 .mu.M NMMP, respectively. NMMP also caused the accumulation of intracellular protoporphyrin. The ability of NMMP to cause intercellular accumulation of protoporphyrin and to block PC synthesis specifically while allowing normal Chl formation is consistent with this action as a specific inhibitor of enzymic Fe chelation and supports the role of heme as a precursor to the phycobilins.