Abstract
The pig lens membrane is primarily composed of four different phospholipids (PLs): phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, and sphingomyelin, with phosphatidylcholine being the most abundant. Cholesterol is an important sterol found in the pig lens membrane where the cholesterol to phospholipid ratio (Chol/PL) is ~1 and ~2 in the cortical and nuclear membrane, respectively. We studied the mechanical properties of a model pig lens membrane with a Chol/PL mixing ratio of 0 and 1 using atomic force microscopy (AFM). We found that the supported pig lens model membrane of Chol/PL ratio 0 displayed two phases: solid ordered phase ( s o ) and liquid disordered phase ( l d ); the height difference between these two phases was approximately 1 nm. The membrane of Chol/PL mixing ratio 1 had only one phase, liquid ordered phase ( l o ). We obtained two different breakthrough forces for the membrane of Chol/PL mixing ratio of 0 with an average value of 15.49±2.8 nN and 4.83±0.31 nN, related to s o and l d , respectively. The membrane of Chol/PL mixing ratio 1 with only one phase, l o , had an average break through force of 10.62±0.39 nN. The elasticity of the membrane, quantified by the area compressibility modulus (K A ), of the membrane with Chol/PL mixing ratio 1 was obtained as 1060±230 mN/m.
| Original language | American English |
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| State | Published - 12 Jul 2021 |