MECHANISMS OF INTERACTION OF ALBUMIN WITH ARTERIAL ELASTIN

Binding of proteins, lipoproteins and calcium salts to arterial elasti n occurs with age and in disease. In order to clarify the mechanisms o f interaction we investigated the binding of native and charge-modifie d albumins to elastin isolated by alkali extraction of the porcine aor ta. Fluorescence microscopy was used to quantify the distribution of l issamine-rhodamine labelled albumins in native and charge-modified ela stins under different solution conditions. For native albumin uptake w as approximately twice as high on the intimal and adventitial sides as in the mid media. The distribution of anionic albumin was very simila r, but methylation either of the albumin or the elastin greatly reduce d the transmural variation. The uptake of methylated albumin was appro ximately three-fold greater than the native albumin. The uptake of the native albumin was reduced preferentially in the intimal region in th e presence of calcium and only the charge-modified proteins were able to penetrate the intralamellar space. These observations demonstrated the importance of hydrophobic interactions in albumin binding.