CETP AND EXCHANGEABLE APOPROTEINS - COMMON FEATURES IN LIPID-BINDING ACTIVITY

In order to define the active domain for lipid binding in CETP (choles teryl ester transfer protein), our study discusses some fundamental ph ysicochemical properties of this molecule such as hydrophobic moment, protein active surface and helix amphipathicity, in comparison to the properties reported for a series of apoproteins including apoAI, apoAI I, apoCI, CII, CIII and apoE. Our study suggests that CETP corresponds to a protein with an active surface slightly lower than the one calcu lated for the exchangeable apoproteins AI, AII, CI, CII, CIII and E. A rrays type (i, i + 3) and (i, i + 4) were found in the region associat ed to lipid binding in these apoproteins. Seven such arrays located in the amphipathic a-helices of CETP are also suggested to contribute to the overall lipid binding activity as a consequence of a-helix stabil ity. It is proposed that for lipid binding to occur in both types of m olecules, the possibility of a conformational specificity given by a r edundant stereochemical code can be actively operating.