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Electrophoretic and kinetic characterization of two phenotypes of soluble cytoplasmic L ‐aspartate:2‐oxoglutarate aminotransferase in human liver tissues
Author(s) -
Kanemitsu Fusae
Publication year - 1987
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.1150081111
Subject(s) - biochemistry , phenotype , electrophoresis , incubation , biology , chemistry , pi , gene
Abstract Two phenotypes of soluble cytoplasmic L ‐aspartate:2‐oxoglutarate aminotransferase (AST, EC 2.6.1.1), sAST 1 and sAST 2–1, were partially purified from human liver tissues and characterized by electrophoretic and kinetic analyses. sAST 1 had 2 bands upon electrophoresis on a Cellogel membrane, while sAST 2–1 had 3 bands with an additional anodic one. The frequencies of the two phenotypes of sASTs studied with 1,023 Japanese hemolysates were 98.5% for sAST 1 and 1.5% for sAST 2–1. sAST 1 was electrofocused to 9 bands with pI's ranging from pH 5.5 to 6.1 and sAST 2–1 into 11 bands with pI's ranging from pH 5.3 to 6.1. The molecular weights of the two phenotypes were both estimated to be 95 000. The apparent K m values of the sASTs for L ‐aspartate with endogenous pyridoxal 5‐phosphate (PALP) were both 5.2 mM and those with added PALP were 5.9 mM for sAST 1 and 5.8 mM for sAST 2–1. The apparent K m values for 2‐oxoglutarate with endogenous PALP were both 0.26 mM and those with added PALP were 0.41 mM for sAST 1 and 0.37 mM for sAST 2–1. sAST 2–1 was more heat‐stable than sAST 1 upon incubation at 65 °C for up to 80 min, while both preparations were similarly denatured by treating with up to 4 M urea at 28 °C for 90 min. The two sASTs reacted with anti‐human AST‐IgG separated from AST‐IgG complexes in serum.