Spin-label studies on the sulfhydryl environment in bovine plasma albumin. 2. The neutral transition and the A isomer.
Since we were able to demonstrate that the sulfhydryl group is located in the crevice which opens during the N--F transition (Cornell, C. N., & Kaplan, L. J. (1978) Biochemistry 17 (preceding paper in this issue), the investigation was extended by characterizing the environment during the N--B transition and in the A isomer. The results indicate that the N--B and N--F transitions are very similar in that the sulfhydryl group moves from a restricted to unhindered environment during both. The use of molecular dipstick technique further demonstrated the similarity between the F and A forms. However, since A is a covalently stabilized form of albumin after a pH dependent transition, it retains its properties during subsequent pH changes rather than reverting to the N form. We were thus able to titrate spin-labeled A through the pH range of the acidic transitions without detecting the N--F transition. Isoelectric focusing analysis of A generated during alkaline aging and purified by SP-Sephadex chromatography indicates that it is a mixture of a small number of albumin forms rather than the large number of components once thought to be formed during aging.
D055598:Chemical Phenomena; D002621:Chemistry; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D008301:Maleimides; D011487:Protein Conformation; D012710:Serum Albumin, Bovine; D013113:Spin Labels; D013438:Sulfhydryl Compounds
D008301:Maleimides; D013113:Spin Labels; D013438:Sulfhydryl Compounds; D012710:Serum Albumin, Bovine