Biochemical evolution III: Polymerization on organophilic silica-rich surfaces, crystal–chemical modeling, formation of first cells, and geological clues

Catalysis at organophilic silica-rich surfaces of zeolites and feldspars might generate replicating biopolymers from simple chemicals supplied by meteorites, volcanic gases, and other geological sources. Crystal–chemical modeling yielded packings for amino acids neatly encapsulated in 10-ring channels of the molecular sieve silicalite-ZSM-5-(mutinaite). Calculation of binding and activation energies for catalytic assembly into polymers is progressing for a chemical composition with one catalytic Al–OH site per 25 neutral Si tetrahedral sites. Internal channel intersections and external terminations provide special stereochemical features suitable for complex organic species. Polymer migration along nano/micrometer channels of ancient weathered feldspars, plus exploitation of phosphorus and various transition metals in entrapped apatite and other microminerals, might have generated complexes of replicating catalytic biomolecules, leading to primitive cellular organisms. The first cell wall might have been an internal mineral surface, from which the cell developed a protective biological cap emerging into a nutrient-rich “soup.” Ultimately, the biological cap might have expanded into a complete cell wall, allowing mobility and colonization of energy-rich challenging environments. Electron microscopy of honeycomb channels inside weathered feldspars of the Shap granite (northwest England) has revealed modern bacteria, perhaps indicative of Archean ones. All known early rocks were metamorphosed too highly during geologic time to permit simple survival of large-pore zeolites, honeycombed feldspar, and encapsulated species. Possible microscopic clues to the proposed mineral adsorbents/catalysts are discussed for planning of systematic study of black cherts from weakly metamorphosed Archaean sediments.

沸石（zeolites）与长石（feldspars）的亲有机富硅表面上的催化作用，可利用陨石、火山气体及其他地质来源提供的简单化学物质，生成可自我复制的生物聚合物（biopolymers）。晶体化学模拟已获得可被规整封装于分子筛silicalite-ZSM-5（mutinaite）10元环孔道内的氨基酸（amino acids）堆积结构。针对每25个中性硅四面体位点（Si tetrahedral sites）对应1个催化性铝羟基位点（Al–OH site）的化学组成，其催化组装为聚合物的结合能与活化能计算工作正在推进中。孔道内部交叉区域与外部端面提供了适配复杂有机物种的特殊立体化学特征（stereochemical features）。沿着古风化长石的纳米/微米级孔道迁移的聚合物，结合捕获于磷灰石（apatite）及其他微矿物（microminerals）中的磷与多种过渡金属的作用，或可生成具有自我复制能力的催化生物分子复合物，进而演化出原始细胞生物体（primitive cellular organisms）。首个细胞壁（cell wall）可能源自内部矿物表面，细胞由此演化出保护性生物包膜，并进入营养丰富的"原始汤"环境。最终，该生物包膜可扩展为完整的细胞壁，使细胞获得运动能力并定植于能量充足但环境苛刻的区域。对英格兰西北部沙普花岗岩（Shap granite）中风化长石内部的蜂窝状孔道进行电子显微镜（electron microscopy）观察，发现了现代细菌，这或许可作为太古宙（Archean）细菌的参照。已知的所有早期岩石在地质历史中均经历了高度变质作用（metamorphism），无法保留大孔沸石、蜂窝状长石及被封装的物种。本文还讨论了针对所提出的矿物吸附剂/催化剂的潜在微观线索，用于指导对弱变质太古宙沉积物（Archaean sediments）中黑色燧石（black cherts）的系统性研究规划。