Ultrastructural and biochemical modifications of collagen from tissue of Morbus Dupuytren patients

Small angle X-ray diffraction and biochemical analyses were carried out on normal palmar aponeurosis and on tissue from patients suffering from Dupuytren contractures (MD). Pathological tissue exhibits a higher overall content of collagen III. Type I collagen extracted from pathological tissue has a melting point of 0.8 degrees C higher than that of normal collagen. The only chemical differences compared to normal collagen I are 50% overhydroxylation of lysyl residues and a reduced amount of diglycosylated hydroxylysine residues. Analysis of the electron density distribution inside the collagen repeating period of MD-samples reveals disordered molecular packing in MD samples compared to in normal collagen. The disorder, which is higher in the gap region, is considerably reduced upon stretching.