Characterization of the adsorptive pinocytic capture of a polyaspartamide modified by the incorporation of tyramine residues.
Previously it has been shown (Duncan, R., Starling, D., Rypácek, F., Drobník, J. and Lloyd, J.B. (1982) Biochim. Biophys. Acta 717, 248-254) that incorporation of tyramine residues into poly (alpha, beta-(N-2-hydroxyethyl]-DL-aspartamide (PHEA) greatly increases its rate of pinocytic uptake by rat visceral yolk sacs cultured in vitro. Here we describe the relationship between the tyramine content (1.2-21.9 mol%) of modified PHEA and its rate of uptake by yolk sacs. Above a level of substitution of approximately 10 mol% the rate of uptake rises rapidly, and the concentration-dependence of capture is indicative of uptake by adsorptive pinocytosis. Serum proteins were shown to compete effectively for membrane binding sites, indicating a nonspecific interaction of PHEA-derivatives with the yolk sac membrane. PHEA derivatives of the same tyramine content, but of different mean molecular weights (Mr), were captured at the same rates.
D000327:Adsorption; D000818:Animals; D001798:Blood Proteins / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D010455:Peptides / Q000378:metabolism*; D010873:Pinocytosis; D051381:Rats; D014439:Tyramine / Q000378:metabolism*; D015017:Yolk Sac / Q000378:metabolism
D001798:Blood Proteins; D010455:Peptides; C044870:alpha, beta-poly((2-hydroxyethyl)aspartamide-co-(4-hydroxyphenethyl)aspartamide); C008965:alpha,beta-poly((2-hydroxyethyl)-aspartamide); D014439:Tyramine