Albumin domain structure

Fig. 5. Schematic representation of the domain structure of albumin, the position of the disulfide loops, and the fragments of the molecule that have been isolated. Included in the figure are the cleavage methods used to obtain the fragments plus the regions to which the restricted antibody populations used in these experiments are directed. Reprinted, with permission, from Teale and Benjamin (1976). Copyright by the American Society of Biological Chemists, Inc.

Due possibly to the above mentioned heterogeneity, there is some variability with regard to the conclusions reached by various workers concerning the structure and configuration of bovine serum albumin. Brown (1977) proposed two possible models based on the primary sequence of the protein. He demonstrated that the molecule could possess a triple domain structure with three very similar domains residues 1-190, 191-382, and 383-582. Each domain could then consist of five helical rods of about equal length arranged either in a parallel or an antiparallel manner. His second model consisted of the following (1) a lone subdomain (1-101) (2) a pair of antiparallel subdomains, with their hydrophobic faces toward each other (113-287) (3) another pair of subdomains (314-484) and (4) a lone subdomain (512-582). These structures are supported by the observed helical content of bovine... 

Fig. 3.17. The crystal structure of human serum albumin (HSA) complexed with four molecules ofmyristic acid (from lbj5.pdb [121][122]). The picture shows the domains (I—III) and subdomains (A and B) of HSA. The primary hydrolytic site is located in subdomain IIIA, and two others probably in subdomain IIA. 

Specific domains of proteins (for example, those mentioned in the section Organic Phase ) adsorbed to biomaterial surfaces interact with select cell membrane receptors (Fig. 8) accessibility of adhesive domains (such as specific amino acid sequences) of select adsorbed proteins may either enhance or inhibit subsequent cell (such as osteoblast) attachment (Schakenraad, 1996). Several studies have provided evidence that properties (such as chemistry, charge, and topography) of biomaterial surfaces dictate select interactions (such as type, concentration, and conformation or bioactivity) of plasma proteins (Sinha and Tuan, 1996 Horbett, 1993 Horbett, 1996 Brunette, 1988 Davies, 1988 Luck et al., 1998 Curtis and Wilkinson, 1997). Albumin has been the protein of choice in protein-adsorption investigations because of availability, low cost (compared to other proteins contained in serum), and, most importantly, well-documented conformation or bioactive structure (Horbett, 1993) recently, however, a number of research groups have started to examine protein (such as fibronectin and vitronectin) interactions with material surfaces that are more pertinent to subsequent cell adhesion (Luck et al., 1998 Degasne et al., 1999 Dalton et al., 1995 Lopes et al., 1999). 

Human serum albumin (HSA) is an important transporter of fatty acids, metabolites, drugs, and organic compounds in the circulatory system [93, 94], It is a single polypeptide chain consisting of 585 amino acids. Under physiological conditions (pH 7), HSA adopts a heart-shaped three-dimensional (3D) structure with three homologous domains I—III (Fig. 14) each domain contains two subdomains A and B, which consist of four and six a-helices, respectively [95, 96]. The X-ray structure shows that two halves of the albumin molecule... 

Figure 8.5 shows fluorescence emission spectra of TNS and ANS bound to serum albumin. The two fluorophores do not show the same maximum, although the two fluorophores bind to hydrophobic domains of the protein. This result can be explained mainly by the differences in the structure of the two fluorophores. Also, one could explain the difference in the emission peaks could be due to the higher sensitivity of TNS to hydrophobicity. This interpretation is based on the fact that the peak of TNS emission spectrum is shifted to short wavelengths compared to that of ANS... 

Fig. 1. Illustration of the loop-link-loop pattern in the primary structure of serum albumin. The three domains (I, II, and III) are shown loops are numbered I to9 (LI-L9).

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