RELATIONSHIP OF ROTATIONAL CORRELATION TIME FROM EPR SPECTROSCOPY ANDPROTEIN-MEMBRANE INTERACTION

A study was carried out to determine if rotational correlation time of spin-labeled hen egg lysozyme (HEL) interacting with ultrafiltration membranes could be used to infer protein-membrane interaction. Polysul fone and cellulosic membranes, which have notably different adsorption properties, and membranes with varying pore sizes were used in this s tudy. Based on this study, it was determined that the rotational corre lation time does reflect variations in protein adsorption and pore plu gging on membranes. The rotational correlation times for the highly ad sorbent polysulfone (2.82 x 10(-8) s) were significantly higher than t hose obtained from proteins on cellulosic membranes (0.62 x 10(-8) s) and from those in solution (0.17 x 10(-8) s). Rotational correlation t ime was also increased due to steric hindrance associated with pore pl ugging, although it was not as significant as the adsorption effect. T his study indicates that the rotational time constant can be used to i nfer the type of protein-membrane interaction.