For the purpose of obtaining information about interphases between subunits of human serum albumin (HSA), a new tritium labelling method was adopted. The existence of linear dependence between accessible surface of amino acid residues and their specific radio-activity enabled to obtain information about qualitattive and quantitative amino acid composition of surface layer of protein globule and its large fragments. | Turk J Biol 24 (2000) 345–351 © TÜBİTAK Study of Interphases Between Subunits of Human Serum Albumin By Tritium Labelling Method Elimkhan S. DZHAFAROV Department of Radio-biology and Radio-chemistry, Institute of Botany, Azerbaijan Academy of Sciences Baku-AZIRBAİJAN Received: Abstract:For the purpose of obtaining information about interphases between subunits of human serum albumin (HSA), a new tritium labelling method was adopted. The existence of linear dependence between accessible surface of amino acid residues and their specific radio-activity enabled to obtain information about qualitattive and quantitative amino acid composition of surface layer of protein globule and its large fragments. It is shown that the fragments surface characterized by higher accessibility of hydrophobic amino acid residues such as Ala, Val, Leu, Ile, Pro and Phe. Moreover Lys, Asx and Glx demonstrate high accessibility also. It is supposed that the spatial HSA molecule organization can be heterogeneous in respect to density of intramolecular packing which is alternation of “dense” and mainly hydrophobic “friable” globule parts; except of hydrophobic residues Lys, Asx and Glx ones have also a tendency to become localized at subunits borders, because these residues could promote to formation of salt bridges which are stipulating and additional stability of “friable” parts at neutral pH. Key Words: Tritium labelling method, HSA, interphase between subunits, accessible surface, space structure. İnsan Serum Albuminin Alt Birimleri Arasındaki İnterfazların Tritiyum’la İşaretleme Metodu ile İncelenmesi Özet: İnsan serum albuminin alt birimleri arasındaki interfazlar hakkında bilgi elde etmek için bir tritiyum’la işaretleme metodu bu incelemeye uygun hale getirilmiştir. Amin asidi rezidülerinin ulaşılabilir yüzeyleri ile bunların özgül radyoaktiviteleri arasında lineer bir ilişkinin mevcut olması, protein globülleri ve bunların iri parçacıklarının yüzeylerindeki amin .
