ISSN:
0173-0835
Keywords:
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
The 21 free amino acids commonly encountered in proteins have been transformed into “carrier ampholyte” species by reacting their primary amino groups with dansyl chloride. These derivatives can thus be focused in an immobilized pH gradient covering the pH 3.1 to 4.1 interval, except for arginine, which still retains a pI of 8.8. Due to their inherent fluorescence, the dansyl derivatives are revealed in UV light, with a sensitivity of the order of 2-4 ng/mm2. All nearest neighbors are separated except for the following couples: Asn-Gln, Gly-Thr, Val-Ile and Cys-Cys2, with a resolving power, in a ΔpI scale, of the order of 0.0018 pH units. Except for a few cases (notably the aromatic amino acids) the order of pI values is well correlated with the pK values of carboxyl groups, suggesting that the latter are not altered by dansylation. From the set of pKCOOH -pI values of the different amino acids, the pK of the tertiary amino group in the dansyl label has been calculated to be 5.11 ± 0.06. Knowing the pK of the amino-dansyl and the pI of the excess, free dansyl label (pI = 3.34) we have derived, for its sulfonic acid group, a pK of 1.57.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/elps.1150070305
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