禽肝线粒体谷氨酰胺合成酶的特性研究

Characterization of glutamine synthetase from avian liver mitochondria.

Vorhaben J E, Smith D D, Campbell J W

Int J Biochem. 1982;14(8):747-56. doi: 10.1016/0020-711x(82)90012-x.

Abstract

Glutamine synthetase has been purified to homogeneity from chicken liver mitochondria. 2. The native enzyme is an octamer composed of identical subunits with monomeric mol. wt of 42,000 dalton. 3. Apparent Kms for NH4+, ATP and glutamate were 0.5, 0.9 and 6 mM, respectively. D-Glutamate and L-alpha-hydroxyglutarate were utilized as substrates with activities approx. 40% those obtained with glutamate. Of several nucleotides tested, none were effective replacements for ATP. 4. Heavy metal ions were inhibitory as were Mn2+, Ca2+ and lanthanide ions. 5. Despite its different subcellular localization and physiological function, avian glutamine synthetase is markedly similar to the weakly-bound microsomal rat liver enzyme with respect to a number of physical and chemical properties.

摘要

谷氨酰胺合成酶已从鸡肝线粒体中纯化至同质。2. 天然酶是由相同亚基组成的八聚体，单体分子量为42,000道尔顿。3. NH4+、ATP和谷氨酸的表观Km分别为0.5、0.9和6 mM。D-谷氨酸和L-α-羟基戊二酸作为底物时，活性约为谷氨酸的40%。在测试的几种核苷酸中，没有一种能有效替代ATP。4. 重金属离子以及Mn2+、Ca2+和镧系离子具有抑制作用。5. 尽管禽谷氨酰胺合成酶的亚细胞定位和生理功能不同，但在许多物理和化学性质方面，它与大鼠肝微粒体弱结合酶明显相似。