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COMPARATIVE PEPTIDE MAPPING AND ISOELECTRIC FOCUSING OF ISOLATED SUBUNITS FROM CHICK EMBRYO BRAIN TUBULIN
Author(s) -
Nelles Lynn P.,
Bamburg James R.
Publication year - 1979
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1979.tb00374.x
Subject(s) - isoelectric focusing , isoelectric point , protein subunit , peptide , amino acid , trypsin , biochemistry , tubulin , polyacrylamide gel electrophoresis , acrylamide , biology , pi , urea , chemistry , microbiology and biotechnology , chromatography , enzyme , genetics , microtubule , monomer , gene , organic chemistry , polymer
— The α‐ and β‐subunits of chick embryo brain tubulin have been isolated under denaturing conditions and compared with respect to their molecular weight, amino acid composition, tryptic peptide maps, amide content and isoelectric focusing properties. An 8 M‐Urea‐containing polyacrylamide gel system with varying acrylamide concentrations was used for calculation of the retardation coefficients (K R ) of the tubulin subunits. A molecular weight of 53,000 was estimated for each subunit by comparison to K R values for standard proteins. Amide contents of approx 41% of the carboxyl groups of α‐tubulin and 48% of the carboxyl groups of β‐tubulin were calculated using the average PI value, the p K intrinsic for the ionizable side chains of the amino acids and the amino acid composition of each subunit. Comparative peptide maps of trypsin digested α‐ and β‐tubulin demonstrated 16 peptides unique to each subunit and 23 peptides which comigrate. Both subunits give rise to multiple species on electrofocusing gels. The average isoelectric points for the α‐ and β‐subunits are 5.4 and 5.2, respectively.