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Conformational changes in cystine disulfide bridges of bovine serum albumin during acid-induced isomerization (N -»F and F -> E transitions) have been studied with Raman spectroscopy. In an X-ray crystallographic study of human serum albumin, Carter and Ho reported that all disulfide bridges of the albumin molecule are in the gauche-gauche-gauche conformation [1]. On the other hand, the solution structure of bovine serum albumin examined by Raman spectroscopy differs from its crystal structure in the conformation of some of the disulfide bridges. Two Raman bands were detected at 520 and 505 cm * in the disulfide stretching mode region, suggesting that the 17 disulfide bridges in the N-form of bovine serum albumin solution take both the gauche-gauche-gauche and gauche-gauche-trans conformations. The ratio of the peak intensities at 520 and 505 cm _1 (I505/I520) is increased from 1.6 to 2.1 and from 2.1 to 6.3 on going from the N-to the F-form and from the F-to the Eform, respectively, indicating that the gauche-gauche-trans conformation of the disulfide bridges is converted to a gauchegauche-gauche one which is the most energetically stable form during the acid-induced isomerization. However, small amounts of gauche-gauche-trans conformation still remain even in the E-form.

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High‐performance liquid chromatographic (HPLC) analysis of human serum albumin (HSA) on Asahipak GS‐520 showed at least two peaks, the principal component corresponding to human mercaptalbumin (HMA) and the secondary one to nonmercaptalbumin (HNA). HPLC analysis of HSA on Asahipak ES‐520 N showed three peaks, the principal component corresponding to HMA, the secondary one to HNA having mixed disulfide with cysteine or glutathione and the tertiary one to HNA oxidized higher than mixed disulfide. Two kinds of rapid HPLC for the resolution of HSA into HMA and HNA were developed by the present authors. Using these HPLC, the present authors found a significant decrease in the fraction of HMA in the elderly.

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Gel-exclusion high-performance liquid chromatographic (HPLC) analysis of human serum albumin (HSA) on PGP 2000 column ( 0 . 1 0~ sodium phosphate buffer, 0.30~ NaCl, pH 6.86) showed at least two peaks, the principal component corresponding to human mercaptalbumin (HMA) and the second one t o human nonmercaptalbumin (HNA). Mechanism for the separation of HMA and HNA might be due to weak resin-HSA interaction. HPLC analysis of bovine plasma albumin (BPA) showed a single peak on PGP 2000 column. The elution volume of HSA was larger than that of BPA, resulting in a clear resolution of HSA and BPA.