MOLECULAR-SPECIES SPECIFICITY OF PHOSPHOLIPID BREAKDOWN IN MICROSOMAL-MEMBRANES OF SENESCING CARNATION FLOWERS
MOLECULAR-SPECIES SPECIFICITY OF PHOSPHOLIPID BREAKDOWN IN MICROSOMAL-MEMBRANES OF SENESCING CARNATION FLOWERS
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DOI：
10.1104/pp.85.3.679
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发表时间：
1987-11-01
期刊：
影响因子：
7.4
通讯作者：
THOMPSON, JE
中科院分区：
文献类型：
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作者：
BROWN, JH;LYNCH, DV;THOMPSON, JE
香石竹切花衰老过程中微粒体磷脂大量分解。这至少部分归因于与微粒体膜直接相关的脂解活性。通过使用放射性标记的磷脂酰胆碱底物，已经获得了表明这些膜中的一种或多种脂质降解酶优先降解含有两个双不饱和酰基链或至少一个多不饱和酰基链的磷脂分子种类的证据。16：0*/16：0*、16：0/18：2* 和18：1*/18：1* 磷脂酰胆碱在3小时内仅被从衰老花中分离的微粒体最低限度地降解。相比之下，[U-14 C]磷脂酰胆碱（包含各种分子种类，包括含有多不饱和酰基链的分子种类）和18：0/20：4* 磷脂酰胆碱被广泛降解。在相同条件下，但在不添加放射性标记底物的情况下，内源性18：2/18：2、18：1/18：3和18：2/18：3磷脂酰胆碱从膜中选择性耗尽。在自然衰老的花，有一个急剧下降的微粒体16：0/18：1和18：1/18：2磷脂酰胆碱，而分子物种含有两个双不饱和酰基链或至少一个多不饱和酰基链保持不变或略有下降。这些数据已被解释为表明，提供特定的分子种类易受脂肪酶的攻击是一个先决条件，在衰老膜磷脂catenase。
During senescence of cut carnation [Dianthus caryophyllus] flowers, there is extensive breakdown of microsomal phospholipid. This is attributable, at least in part, to lipolytic activity associated directly with the microsomal membranes. Evidence indicating that one or more of the lipid-degrading enzymes in these membranes preferentially degrade phospholipid molecular species containing two diunsaturated acyl chains or at least one polyunsaturated acyl chain has been obtained by using radiolabeled phosphatidylcholine substrates. 16:0*/16:0*, 16:0/18:2*, and 18:1*/18:1* phosphatidylcholine were degraded only minimally over a 3 hour period by microsomes isolated from senescing flowers. By contrast, [U-14C]phosphatidylcholine, which comprises various molecular species including those containing polyunsaturated acyl chains, and 18:0/20:4* phosphatidylcholine were extensively degraded. Under identical conditions, but in the absence of added radiolabeled substrate, endogenous 18:2/18:2, 18:1/18:3, and 18:2/18:3 phosphatidylcholine were selectively depleted from the membranes. During natural senescence of the flowers, there was a sharp decline in microsomal 16:0/18:1 and 18:1/18:2 phosphatidylcholine, whereas molecular species containing two diunsaturated acyl chains or at least one polyunsaturated acyl chain remained unchanged or decreased only slightly. The data have been interpreted as indicating that provision of particular molecular species susceptible to lipase attack is a prerequisite to phospholipid catabolism in senescing membranes.