大麦初生叶中质外体的蛋白、酯酶和苹果酸脱氢酶同工酶(英文)

Soluble and Bound Apoplastic Proteins and Isozymes of Esterase and Malate Dehydrogenase in Barley Primary Leaves

把6天株龄的大麦(Hordeum vylgare L.)初生叶的下表皮剥去后,以含pH6.5的200mmol/L NaCl缓冲液真空渗洗叶片36min,获得的细胞间隙洗液含有水溶性或弱离子结合态的质外体蛋白质和酶。渗洗过的叶片用缓冲液磨成匀浆和离心后,上清液含原质体蛋白质和酶。用1mmol/L NaCl可溶解离子结合态的质外体蛋白质和酶,两条(25和31kD)和7条(22,28,30,51,55,60和71kD)蛋白质带只分别在含有200mmol/L和1mmol/L NaGl的质外体提取液中测得。机械创伤诱导两条(32和33kD)可溶于200mmol/L NaCl的质外体蛋白带,在质外体还测到3条可溶于200mmol/L NaCl和4条可溶于1mmol/L NaCl的苹果酸脱氢酶同工酶。在质外体和共质体两部分均发现有酯酶Ⅰ同工酶,但移向阴极的酯酶同工酶Ⅰ只见于溶在200mmol/L NaCl的质外体中。移向阳极的酯酶Ⅱ同工酶仅见于共质体中。

The apoplast of plant cells is a dynamic compartment which responds to different environmental and mechanical stresses by synthesizing and degrading cell wall associated components. To better understand this compartmentation we used a vacuum-infiltration technique, SDSPAGE and starch gel electrophoresis, to study the apoplastic proteins and isozymes of esterase and malate dehydrogenase (MDH)in 6 day old barley (Hordeura vulgare L.) primary leaves. An intercellular washing solution (IWS) ontaining soluble or weakly bound apoplastic protein was obtained by infiltrating the peeled leaf segments with pH 6.5 buffered 200mmol/L NaCl. Washed segments were homogenized in buffer and centrifuged, and the supernatant was used as a source of soluble symplastic constituents. Ionically bound proteins were extracted from the washed wall pellets with 1 mol/L NaCl. Two IWS proteins (25 and 31 kilodalton, kD) and seven ionically bound proreins (22, 28, 30, 51, 55, 60 and 71 kD) were restricted to the apoplast. Mechanical wounding induced at least two new IWS proteins (32 and 33 kD). MDH isozymes were well-resolved in the apoplastic fractions (two IWS, four ionically bound). These apoplastic MDH isozymes were also detected in the symplast. Esterase Ⅰ isozymes were detected in both apoplastic and symplastic fractions. Cathodic esterase Ⅰ isozymes were found only in the IWS, and esterase Ⅱ isozyrues were detected only in the symplastic fraction. The possible involvement of these apoplastic proteins and isozymes in cell wall differentiation and in response to mechanical wounding is discussed.