2023 Undergraduate Research Showcase


Interaction of Beta-Crystallin with Membrane: A Study Using Atomic Force Microscopy

Document Type

Student Presentation

Presentation Date


Faculty Sponsor

Dr. Laxman Mainali


Eye lens fiber cells comprise crystallin proteins (α-, β-, and γ-) that ensure the lens's transparency and structure. Several experiments have been performed regarding the interaction of lens membrane with α-crystallin, however limited experiments with non-concurring results are present regarding the interaction of β-crystallin with membrane. In this work, we use atomic force microscopy (AFM) to study the interaction of β-crystallin with the model membrane. A multilamellar suspension solution of 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine (POPC) lipid was prepared using a rapid solvent exchange method followed by probe-tip sonication to generate small unilamellar vesicles (SUV). A supported lipid membrane (SLM) was prepared by dispensing SUV solution on top of the mica disc and examined with AFM to verify the defect-free membrane. We incubate β-crystallin solution on top of SLM to observe the interaction by AFM. Topographical images and force curves were acquired by AFM and further processed to obtain the image roughness and breakthrough force. After incubating β-crystallin with the SLM, almost circular membrane defects of ~2 nm depth were observed in random places, indicating the interaction of β-crystallin to the SLM. Force curves in the region outside the defects were similar to the control membrane; however, no breakthrough events were observed in the membrane defect region. The absence of breakthrough events indicates the loss of membrane elasticity. The membrane's elastic properties in the defect-free membrane region were similar to the control membrane's elastic properties. The image roughness of the defect-free membrane area after adding β-crystallin solution was not significantly different from the control membrane.

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