Accuracy in the Determination of Isoelectric Points of Some Proteins and a Peptide by Capillary Isoelectric Focusing:  Utility of Synthetic Peptides as Isoelectric Point Markers

2000 ◽  
Vol 72 (19) ◽  
pp. 4747-4757 ◽  
Author(s):  
Kiyohito Shimura ◽  
Wang Zhi ◽  
Hiroyuki Matsumoto ◽  
Ken-ichi Kasai
2013 ◽  
Vol 85 (12) ◽  
pp. 6089-6094 ◽  
Author(s):  
Yvonne E. Thomassen ◽  
Gerco van Eikenhorst ◽  
Leo A. van der Pol ◽  
Wilfried A. M. Bakker

2011 ◽  
Vol 32 (20) ◽  
pp. 2857-2866 ◽  
Author(s):  
Marie Lecoeur ◽  
Jean-François Goossens ◽  
Claude Vaccher ◽  
Jean-Paul Bonte ◽  
Catherine Foulon

1982 ◽  
Vol 203 (2) ◽  
pp. 427-433 ◽  
Author(s):  
N UI ◽  
C Takasaki ◽  
N Tamiya

The isoelectric points of erabutoxins a, b and c, neurotoxic proteins of a sea snake, Laticauda semifasciata, were determined by density-gradient isoelectric focusing. The same measurement was also made with monoacyl derivatives of erabutoxin b, in which each one of all amino groups had been either acetylated or propionylated. Erabutoxins a and b showed the same isoelectric point at pH 9.68. The values for [1-N alpha-acetyl-arginine]-, [15-N6-acetyl-lysine]-, [27-N6-acetyl-lysine]-, [47-N6-propionyl-lysine]- and [51-N6-acetyl-lysine]-erabutoxin b were at pH 9.52, 9.31, 9.45, 9.22 and 9.09 respectively, being definitely different from each other and lower than the value for the unmodified molecule. The isoelectric point of erabutoxin c, which is [51-asparagine]-erabutoxin b, was the same as that of [51-N6-acetyl-lysine]erabutoxin b. Assuming that no change in pK occurs on monoacylation, the pK values of amino groups in erabutoxin b were calculated from the isoelectric-point data. It is indicated that the pK values of zeta-amino groups differ markedly from each other and that the value of alpha-amino group is anomalously high.


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