Comparative study of the microstructure of solid rubber from Ficus carica and Hevea brasiliensis
Comparative study of the microstructure of solid rubber from Ficus carica and Hevea brasiliensis
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DOI：
10.1002/pat.5441
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发表时间：
2021-07
影响因子：
3.4
通讯作者：
Saki Yokota‐Imai;S. Chida;Takehiro Suzuki;N. Dohmae;T. Gotoh
中科院分区：
文献类型：
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作者：
Saki Yokota‐Imai;S. Chida;Takehiro Suzuki;N. Dohmae;T. Gotoh
巴西橡胶树（Hevea brasiliensis，Hb）天然橡胶具有独特的网络结构，由蛋白质和磷脂等次要非橡胶组分形成分支点，连接主要橡胶组分顺式-1，4-聚异戊二烯链。然而，无花果固体橡胶的结构尚不清楚。在这项研究中，我们研究了从Fc固体橡胶的微观结构和蛋白质组成。透射电子显微镜分析表明，FC固体橡胶中的非橡胶组分形成了一个不均匀的框架，许多橡胶颗粒融合在一起。我们确定，无花果蛋白酶，半胱氨酸内切蛋白酶，是一个主要的蛋白质在Fcrubber。无花果蛋白酶似乎降解了与橡胶颗粒相关的蛋白质，而不是作为连接Fcrubber中的顺-1，4-聚异戊二烯链的蛋白质。我们还发现，一个大的凝胶级分，分离后的溶解Hbsolid橡胶在甲苯中，在Fc solid橡胶缺席。这些结果表明，在Fcrubber中不存在蛋白质分支点。此外，酯交换橡胶的尺寸排阻色谱-多角度光散射（SEC‐MALS）分析表明，Fcrubber中不存在由磷脂组成的分支点。在此基础上，提出了FC固体橡胶中橡胶颗粒的微观结构，并讨论了微观结构与橡胶链结构之间的关系。
Natural rubber fromHevea brasiliensis(Hb) is known to have a characteristic network structure, with branch points formed by minor nonrubber components such as proteins and phospholipids that connect the major rubber component,cis‐1,4‐polyisoprene chains. However, the structure of solid rubber fromFicus carica(Fc) is not well known. In this study, we examined the microstructure and protein composition of solid rubber fromFc. Transmission electron microscopy analysis ofFcsolid rubber revealed that the nonrubber components formed a nonuniform framework in the rubber matrix, and that many rubber particles were fused together. We determined that ficin, a cysteine endoproteolytic protease, was a major protein in theFcrubber. It appears that ficin degrades the proteins associated with rubber particles rather than acting as a protein connecting thecis‐1,4‐polyisoprene chains inFcrubber. We also found that a macrogel fraction, which separated after the dissolution ofHbsolid rubber in toluene, was absent in theFcsolid rubber. These results suggest that there are no proteinous branch points inFcrubber. Furthermore, size exclusion chromatography with multiangle light scattering (SEC‐MALS) analysis of the transesterified rubber demonstrated that no branch points composed of phospholipids were involved inFcrubber. On the basis of our results, we propose a microstructure for the rubber particles inFcsolid rubber and discuss the relationship between the microstructure and the structure of the rubber chains within it.