STUDY OF HUMAN SERUM-ALBUMIN STRUCTURE BY DYNAMIC LIGHT-SCATTERING - 2 TYPES OF REACTIONS UNDER DIFFERENT PH AND INTERACTION WITH PHYSIOLOGICALLY ACTIVE COMPOUNDS

The effect of pH and binding of ten physiologically active compounds ( isoproterenol, yohimbine, propranolol, clonidine, phenylephrine, carba chol, tripeptide fMLP, diphenhydramine, chlorpromazine and atropine) o n the molecular structure of human serum albumin (HSA) has been studie d using the dynamic light scattering. It was found that albumin globul e has the most compact configuration (Stokes diameter 59-62 Angstrom) at physiological pH 7.4. The changes in pH, both increase to 8.0 and d ecrease to 5.4, result in the growth of globule size to 72-81 Angstrom . At acidic shift of pH an additional peak arises in the correlation s pectra caused by the Light scattering on the structures with the Stoke s diameters of 29-37 Angstrom. Those conform to the sizes of the album in subdomains. The indicated peak is not displayed at basic shift of p H. The interaction with propranolol, clonidine, phenylephrine, carbach ol and tripeptide fMLP which hinder adenylate cyclase (AdC) and activa te Ca-polyphosphoinositide (Ca-PPI) signaling system of a cell initiat es structural rearrangements similar to acidic transitions. Isoprotere nol, yohimbine diphenhydramine, chlorpromazine and atropine, which act ivate AdC and hinder Ca-PPI, cause conformational changes of HSA simil ar to basic transitions. (C) 1998 Elsevier Science B.V. All rights res erved.