Force-Induced Dissociation of Single Protein A-IgG Bonds

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• 作者：Markus Strigl ; Doris A. Simson ; Claudia M. Kacher ; and Rudolf Merkel
• 刊名：Langmuir
• 出版年：1999
• 出版时间：October 12, 1999
• 年：1999
• 卷：15
• 期：21
• 页码：7316 - 7324
• 全文大小：131K
• 年卷期：v.15,no.21(October 12, 1999)
• ISSN：1520-5827

文摘

We investigated the force-induced dissociation of single specific bonds between biomolecules. For theseexperiments we used a micropipet-based picoforce transducer. It consisted of a red blood cell tensed bymicropipet suction. The stiffness of this "spring" was tuned by suction pressure. The proteins underinvestigation were immobilized onto microbeads. One type of bead carried the adhesion proteins and wasbiochemically attached to the red blood cell membrane. The second type, carrying the respective ligand,was held in a second micropipet which was moved by a piezoelectric transducer. Complementary beadswere repeatedly brought into contact in order to form and break bonds. Yield forces exceeding 3 pN couldbe detected. For protein binding, the microbeads were covalently coated with a hydrogel of several nanometerthickness onto which the proteins were bound. This preparation resulted in a low frequency of nonspecificinteractions between the beads. Linkages between beads and proteins were of sufficient strength formechanical experiments on single molecules. We controlled the number of available binding sites bycompetitive blocking with soluble ligand so that only single molecular bonds were present between themicrobeads. Protein A-IgG bonds were studied. Here we found a marked dependence of bond strengthon the rate of force application. This effect is due to a force dependent rate of bond dissociation.