家蚕丝氨酰 - tRNA合成酶。纯化及性质

Seryl-tRNA synthetase from Bombyx mori. Purification and properties.

作者信息

Viswanathan S, Dignam J D

机构信息

Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505.

出版信息

J Biol Chem. 1988 Jan 5;263(1):535-41.

PMID:2826448

Abstract

Seryl-tRNA synthetase has been purified from the middle silk glands of Bombyx mori by successive chromatography on DEAE-Sephacel, hydroxylapatite, and Bio-Rex 70. The high abundance of seryl-tRNA synthetase in the middle silk glands may result from an adaptation of this organ for the production of the serine-rich protein, sericin. The enzyme is a dimer of Mr = 124,000 consisting of similar or identical subunits and has an oligomeric structure similar to its procaryotic and eucaryotic counterparts. Seryl-tRNA synthetase can be cleaved with trypsin to generate a fragment of Mr = 45,000 on sodium dodecyl sulfate gels; the presence of tRNASer protects the enzyme from tryptic cleavage. Conversion to the Mr = 45,000 species is accompanied by a 90% loss in aminoacyl-tRNA synthetase activity, but only a 20% loss in ATP PPi exchange activity.

摘要

丝氨酰 - tRNA合成酶已通过先后在DEAE - 葡聚糖凝胶、羟基磷灰石和Bio - Rex 70上进行层析，从家蚕的中部丝腺中纯化出来。中部丝腺中丝氨酰 - tRNA合成酶的高丰度可能是该器官为生产富含丝氨酸的蛋白质丝胶蛋白而产生的一种适应性结果。该酶是一个Mr = 124,000的二聚体，由相似或相同的亚基组成，并且具有与其原核和真核对应物相似的寡聚结构。丝氨酰 - tRNA合成酶可以用胰蛋白酶切割，在十二烷基硫酸钠凝胶上产生一个Mr = 45,000的片段；tRNASer的存在可保护该酶不被胰蛋白酶切割。转化为Mr = 45,000的物种伴随着氨酰 - tRNA合成酶活性90%的损失，但ATP焦磷酸交换活性仅损失20%。