Pressure Jump Studies of Proteins. I. Isomerization of Bovine Serum Albumin at Neutral pH

1971 ◽  
Vol 49 (12) ◽  
pp. 1267-1275 ◽  
Author(s):  
D. E. Goldsack ◽  
P. M. Waern

Pressure jump kinetic studies of the conformational change occurring in bovine serum albumin in neutral solutions have been carried out over the pH range 6.5–9.5. Two distinct relaxation effects are observed at each pH. The faster relaxation is attributed to binding of the dye to the protein, and the slower relaxation is related to the conformational change occurring in the protein. This slower relaxation effect is pH dependent with a maximum value near pH 8. Detailed analysis of these data leads to a mechanism for the conformational change which indicates that the one form of the protein has an ionizable group with a pK of 8.7 which changes to a pK of 6.7 when the protein undergoes the conformational change. A simple iterative procedure is given for analyzing the pH dependence of a relaxation time constant for a cyclic mechanism involving only one ionizing group controlling the conformational change.

1986 ◽  
Vol 236 (1) ◽  
pp. 307-310 ◽  
Author(s):  
M Y Khan

The domain III of bovine serum albumin containing residues 377-582 of the protein sequence was isolated and its behaviour in acid solution was studied. The fragment was found to undergo structural transformations over the pH range 3.5-4.5 known to cause N-F transition in serum albumin. On the other hand, an albumin fragment that was devoid of domain III was unable to exhibit such a transition. These results were consistent with a mechanism where N-F transition involves the separation of domain III from the rest of the albumin starts at about pH 4.3 and is completed at pH 3.5.


2015 ◽  
Vol 63 (16) ◽  
pp. 4080-4086 ◽  
Author(s):  
Shuqin Xia ◽  
Yunqi Li ◽  
Qin Zhao ◽  
Ji Li ◽  
Qiuyang Xia ◽  
...  

1975 ◽  
Vol 42 (2) ◽  
pp. 267-275 ◽  
Author(s):  
J. G. Zadow ◽  
R. D. Hill

SummaryCarboxymethyl cellulose (CMC) formed insoluble complexes with β-lactoglobulin, bovine serum albumin and Na caseinate. Maximum precipitation of the β-lactoglobulin-CMC complex occurred at pH 3·2, whereas maximum precipitation of the bovine serum albumin-CMC complex and the Na caseinate-CMC complex occurred at pH 2·8. The ratio of CMC to protein for maximum precipitation depended on the protein, being greatest for Na caseinate and least for bovine serum albumin. The percentage of protein precipitated by CMC decreased with increasing ionic strength of the solution, the rate of decrease being least for bovine serum albumin. At a given ionic strength, more protein was precipitated by CMC of high degree of substitution than by CMC of low degree of substitution. The change in pH (ΔpH) occurring on mixing CMC and unbuffered protein solutions, each initially at the same pH, was measured. ΔpH was negative for β-lactoglobulin-CMC mixtures over the pH range 7–2 (minimum at pH 5·5). For bovine serum albumin-CMC and Na caseinate-CMC mixtures, ΔpH was positive between pH 7 and 3·2 (maximum at pH 4·5), zero at pH 3·2 and negative between pH 3·2 and 2·0 (minimum at pH 2·8).


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