Electrophoretic and kinetic characterization of two phenotypes of soluble cytoplasmic L-aspartate:2-oxoglutarate aminotransferase in human liver tissues
✍ Scribed by Dr. Fusae Kanemitsu
- Publisher
- John Wiley and Sons
- Year
- 1987
- Tongue
- English
- Weight
- 346 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0173-0835
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✦ Synopsis
Electrophoretic and kinetic characterization of two phenotypes of soluble cytoplasmic ~-aspartate:2-oxoglutarate aminotransferase in human liver tissues
Two phenotypes of soluble cytoplasmic ~-aspartate:2-oxoglutarate aminotransferase (AST, EC 2.6.1. l), sAST 1 and sAST 2-I , 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 I and 1.5 96 for sAST 2-1. sAST 1 was electrofocused to 9 bands with PI'S ranging from pH 5.5 to 6. I and sAST 2-1 into 1 1 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 , values of the sASTs for L-aspartate with endogenous pyridoxal5-phosphate (PALP) were both 5.2 mM and those with added PALP were 5.9 mM for sAST I and 5.8 mM for sAST 2-1. The apparent I(, values for 2-oxoglutarate with endogenous PALP were both 0.26 mM and those with added PALP were 0.4 1 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 OC for up to 80 min, while both preparations were similarly denatured by treating with up to 4 M urea at 28 OC for 90 min. The two sASTs reacted with anti-human AST-IgG separated from AST-IgG complexes in serum.