The molecular dimensions of mitogenic factor from guinea pig lymph node cells

Area of Science:

• Immunology
• Molecular Biology
• Biophysics

Background:

• Mitogenic factors play a crucial role in immune responses by stimulating lymphocyte proliferation.
• Understanding the biophysical properties of these factors is essential for elucidating their function in cell signaling.

Purpose of the Study:

• To determine the molecular dimensions and physicochemical properties of a mitogenic factor derived from guinea pig lymph node cells.
• To characterize the molecular weight, sedimentation coefficient, and buoyant density of the purified mitogenic factor.

Main Methods:

• Gel filtration chromatography (Sephadex G-100) to estimate the diffusion coefficient (D-20,w).
• Sucrose density gradient ultracentrifugation to determine the apparent sedimentation coefficient (S20,w).
• Cesium chloride (CsCl) isopycnic ultracentrifugation to measure buoyant density and partial specific volume.

Main Results:

• The diffusion coefficient (D-20,w) was determined to be (9.9 ± 0.2) x 10^-7 cm²/sec.
• The apparent sedimentation coefficient (S20,w) was estimated at 2.4 ± 0.2 S.
• Buoyant density was measured at 1.324 ± 0.006 g/ml, leading to a calculated molecular weight of approximately 20,000 and a frictional ratio of 1.2.

Conclusions:

• The study successfully characterized the molecular weight and dimensions of a mitogenic factor from guinea pig lymph nodes.
• The calculated molecular weight of 20,000 suggests a specific size for this immune signaling molecule.
• These findings contribute to a deeper understanding of the molecular mechanisms underlying immune cell activation.