Cavarra E, Santucci A, Lungarella G
Institute of General Pathology, University of Siena, Italy.
Biol Chem Hoppe Seyler. 1995 Jun;376(6):371-7. doi: 10.1515/bchm3.1995.376.6.371.
Cathepsin G was isolated from granules of rabbit bloodstream leukocytes and purified to apparent homogeneity by a multi-step procedure consisting of ammonium sulphate precipitation, affinity chromatography on elastin-Sepharose, and finally by ion-exchange chromatography on a CM-52 column. The molecular weight of the enzyme, as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), was 27,000. The first 24 N-terminal amino-acids were determined and showed 96%, 92% and 79% identity respectively to those of human, dog and rat cathepsin G. Despite the difference in the total amino-acid composition of cathepsin G between rabbit and other mammalian species, close similarities have been found in their substrate specificity and inhibition profile. The kcat/Km values of rabbit cathepsin G with Suc-Ala2-Pro-Phe-NA and Suc-Ala2-Pro-Leu-NA are quite similar to those reported for human cathepsin G under the same conditions. The inhibition profile of the isolated enzyme indicates that cathepsin G from rabbits, like that from other mammalians species belongs to the group of serine proteinases. Finally, like human cathepsin G, catalytically active rabbit enzyme is able to induce platelet aggregation.
组织蛋白酶G是从兔血液白细胞颗粒中分离出来的，并通过多步程序纯化至表观均一，该程序包括硫酸铵沉淀、弹性蛋白-琼脂糖亲和层析，最后通过CM-52柱进行离子交换层析。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）测定，该酶的分子量为27,000。测定了前24个N端氨基酸，分别与人、狗和大鼠组织蛋白酶G的前24个N端氨基酸显示出96%、92%和79%的同源性。尽管兔与其他哺乳动物物种的组织蛋白酶G的总氨基酸组成存在差异，但在它们的底物特异性和抑制谱方面发现了密切的相似性。兔组织蛋白酶G与琥珀酰-Ala2-Pro-Phe-NA和琥珀酰-Ala2-Pro-Leu-NA的kcat/Km值与在相同条件下报道的人组织蛋白酶G的kcat/Km值相当相似。分离出的酶的抑制谱表明，兔的组织蛋白酶G与其他哺乳动物物种的一样，属于丝氨酸蛋白酶组。最后，与人类组织蛋白酶G一样，具有催化活性的兔酶能够诱导血小板聚集。
