Pichia pastoris expression system was introduced with post-translation process similar to higher eukaryotes. Preliminary studies were performed toward process intensification and magnetic immobilization of this system. In this experiment, effects of magnetic immobilization on the structure of recombinant protein were evaluated. P. pastoris cell which express human serum albumin (HSA) was used as a model. The cells were immobilized with various concentrations of APTES coated magnetite nanoparticles. HSA production was done over 5 days induction and structure of the product was analyzed by UV–vis, fluorescence, and ATR-FTIR spectroscopy. Second derivative deconvolution method was used to analyze the secondary structure of HSA. P. pastoris cell that were immobilized with 0.5 and 1 mg/mL of nanoparticles were produced HSA with intact structure. But immobilization with 2 mg/mL of nanoparticles resulted in some modifications in the secondary structures (i.e., α-helixes and β-turns) of produced HSA. Based on these data, immobilization of P. pastoris cells with 0.5 or 1 mg/mL of nanoparticles is completely efficient for cell harvesting and has any effect on the structure of recombinant product. These findings revealed that decoration of microbial cells with high concentrations of nanoparticles has some impacts on the structure of secretory proteins.

Pichia pastoris表达系统引入了类似于高等真核生物的翻译后过程。对该系统的过程强化和磁性固定进行了初步研究。本实验评估了磁性固定化对重组蛋白结构的影响。表达人血清白蛋白(HSA)的毕赤酵母细胞用作模型。细胞用不同浓度的 APTES 包被的磁铁矿纳米粒子固定。HSA 生产在 5 天内完成诱导，并通过 UV-vis、荧光和 ATR-FTIR 光谱分析产品的结构。使用二阶导数解卷积方法分析HSA的二级结构。帕斯托里斯用 0.5 和 1 mg/mL 纳米颗粒固定的细胞产生具有完整结构的 HSA。但是用 2 mg/mL 的纳米颗粒固定会导致产生的 HSA 的二级结构（即 α-螺旋和 β-转角）发生一些变化。基于这些数据，用 0.5 或 1 mg/mL 纳米颗粒固定毕赤酵母细胞对于细胞收获是完全有效的，并且对重组产品的结构有任何影响。这些发现表明，用高浓度纳米颗粒装饰微生物细胞对分泌蛋白的结构有一定的影响。