The effect of bovine tendon glycoprotein on the formation of fibrils from collagen solutions.

The formation of collagen fibrils under physiological conditions of ionic strength, pH and temperature was markedly affected by the presence of small amounts of bovine tendon glycoprotein. The absorbance of the gels at 400 nm was decreased, and they took longer to form. Over the range of concentration tested, the negative specific absorbance, -delta Asp., and the specific retardation, Rsp., both increased with the glycoprotein to collagen ratio. When added during the nucleation phase, glycoprotein was still able to exert its effect almost fully, and so must act to inhibit the later stages of fibril formation. Several pieces of evidence showed that glycoprotein acts via a weak binding to the collagen molecule. Electron microscopy established that fibrils formed in the presence of glycoprotein had a normal cross-striation pattern, but were significantly thinner than fibrils formed in control gets. The results suggest that glycoprotein could act in tissues to help regulate the diameter of collagen fibrils.