TRINODULAR STRUCTURE OF FIBRINOGEN - CONFIRMATION BY BOTH SHADOWING AND NEGATIVE STAIN ELECTRON-MICROSCOPY

Fibrinogen molecules sprayed on mica, dried in vacuo and shadowed with platinum appear as trinodular rods. We describe here the flotation technique of negative staining by which we were able to visualize individual fibrinogen molecules. The fibrinogen molecules in our negatively stained preparations have a trinodular structure identical to that of shadowed molecules. We believe that the 20 nm diameter globules seen in previous negative staining studies are aggregates of these molecules. This is the first study in which both shadowed and negatively stained preparations of fibrinogen support a single, consistent model for the structure of fibrinogen. The molecules in our preparation are 45 nm long (±2.5 nm, our overall estimate of accuracy), the two outer nodules are 6 to 7 nm in diameter and the middle nodule is 4 to 5 nm in diameter. © 1979.