X‐ray and primary structure of horse serum albumin (Equus caballus) at 0.27‐nm resolution

Abstract

The amino-acid sequence and three-dimensional structure of equine serum albumin have been determined. The amino-acid sequence was deduced from cDNA isolated from equine liver. Comparisons of the primary structure of equine serum albumin with human serum albumin and bovine serum albumin reveal 76.1 % and 73.9% sequence identity, respectively. The three-dimensional structure was determined crystallographically by the molecular-replacement method using molecular coordinates from the previously determined structure of human serum albumin, to a resolution of 0.27 nm. In accordance with the primary structure, the three-dimensional structures are highly conserved. There is a root-mean-square difference between a-carbons of the two structures of 0.201 nm. The association constants (Ka) for the binding of 2,3,5-triiodobenzoic acid were determined by ultrafiltration methods for equine and human serum albumins to be approximately 1WM-l and 105M-', respectively. Crystallographic studies of equine serum albumin reveal two binding sites for 2,3,5-triiodobenzoic acid identical with those previously reported for human serum albumin which are located within subdomains IIA and IIIA. Details and comparisons of the binding chemistry are discussed.As the most abundant protein of the circulatory system albumin functions as a multipurpose transport molecule and is a principal contributor to colloid osmotic blood pressure.

Determination of Some Hydrodynamic Parameters of Ovine Serum Albumin Solutions Using Viscometric Measurements

“…As seen in Figure 1, Eq. (2) then gives a good approximation to the experimental values, but only up to a concentration of about 320 kg/m 3 . The values of two other parameters are presented in Figure 2.…”

“…These similarities in the overall shape of mammalian albumins is a reflection of their high amino-acid sequence identity. For example, the ESA molecule exhibits the highest sequence identity with HSA (76.1%) followed by porcine serum albumin (76%), OSA (75.5%) and BSA (73.9%) [3].…”

“…Using T h = 318.16 K and the numerical values of the parameters obtained earlier, the above relation gives for OSA: V h = 182 nm 3 . Because -for the prolate ellipsoid of revolution -V h = (4/3)πab 2 and p = a/b, then V h = (4/3)π pb 3 . It gives the values of the main semi-axes of the hydrated OSA molecule: a = 7.4 nm and b = 2.4 nm.…”

“…The differences in amino-acid sequences, in turn, cause some differences in the three-dimensional structure of albumins from various mammals and considerable differences in their physicochemical properties [4,5]. Unfortunately, detailed investigations on the three-dimensional structure of albumins have been performed only for a few species, including human serum albumin (HSA), bovine serum albumin (BSA) and equine serum albumin (ESA) [3,6]. For most species, the three-dimensional structure of albumins and -in particular -their conformations in solution is poorly known.…”

“…Mammalian albumins are moderately large proteins, with molecular mass M p = 66.5 kDa [2]. Determination of aminoacid sequences for several of them showed a common topology and -on the other hand -some differences ( [3] and references therein). The differences in amino-acid sequences, in turn, cause some differences in the three-dimensional structure of albumins from various mammals and considerable differences in their physicochemical properties [4,5].…”