Lachmanová Štěpánka, Kolivoška Viliam, Pospíšil Lubomír, Fanelli Nicolangelo, Hromadová Magdaléna
J. Heyrovský Institute of Physical Chemistry of ASCR, v.v.i., Dolejškova 3, 182 23 Prague, Czech Republic.
Institute of Chemistry of Organometallic Compounds, CNR, via Moruzzi 1, 561 24 Pisa, Italy.
Biointerphases. 2016 Sep 12;11(3):031003. doi: 10.1116/1.4958305.
Adsorption properties of protein Papain at the solid|liquid (0.1 M KCl) interfaces of different hydrophobicity [highly oriented pyrolytic graphite (HOPG), bare gold, CH3, OH, and COOH-terminated self-assembled monolayers on gold] were studied by a combined quartz crystal microbalance and atomic force microscopy techniques. It was found that Papain forms an incomplete monolayer at hydrophobic interfaces (HOPG and CH3-terminated substrate), whereas on more hydrophilic ones, a complete monolayer formation was always observed with either the onset of the formation of a second layer (bare gold substrate) or adsorption in a multilayer fashion, possibly a bilayer formation (OH-terminated substrate). The surface concentration and compact monolayer film thickness was much lower on the COOH-terminated substrate compared to other surfaces studied. This result was explained by partial dissociation of the interfacial COOH groups leading to additional electrostatic interactions between the positively charged protein domains and negatively charged carboxylate anions, as well as to local pH changes promoting protein denaturation.
采用石英晶体微天平与原子力显微镜联用技术，研究了木瓜蛋白酶在不同疏水性固液（0.1M KCl）界面[高度定向热解石墨（HOPG）、裸金、金表面的CH3、OH和COOH端基自组装单分子层]上的吸附特性。结果发现，木瓜蛋白酶在疏水界面（HOPG和CH3端基基底）形成不完整的单分子层，而在亲水性更强的界面上，总是观察到形成完整的单分子层，要么是开始形成第二层（裸金基底），要么是以多层方式吸附，可能形成双层（OH端基基底）。与其他研究表面相比，COOH端基基底上的表面浓度和紧密单分子层膜厚度要低得多。这一结果的解释是，界面COOH基团的部分解离导致带正电的蛋白质结构域与带负电的羧酸根阴离子之间产生额外的静电相互作用，以及局部pH变化促进蛋白质变性。
