Purification of pyroglutamate aminopeptidase and development of assay methods employing its antibody

促甲状腺激素释放激素(TRH)可能在调节饮食行为、体温和意识状态方面发挥作用。另一方面，组氨酸二酮哌嗪(His-Pro)是TRH的内源性代谢产物，本文试图阐明其内源转化为Cyclo(His-Pro)的焦谷氨酸氨基肽酶(PGlup)的性质。2.将牛脑和大鼠脑匀浆分别用Sephacryl S-200和GF-250柱层析纯化pGlup。PGlup蛋白的相对分子质量约为380000。3.本实验室利用纯化的酶蛋白抗体建立了pGlup蛋白的放射免疫分析方法。4.pGlup在大鼠脑内的分布表明，该酶蛋白在小脑和下丘脑中尤为丰富。5.在大鼠发育过程中，脑内pGlup浓度与Cyclo(His-Pro)呈正相关。6.甲状腺功能不全患者与正常人外周血pGlup水平无明显差异。7.部分肌萎缩侧索硬化症患者脑脊液中pGlup水平升高，提示pGlup可能是调节脑Cyclo(His-Pro)含量的重要因素之一。此外，患者血液和脑脊液中pGlup的测定也可作为反映疾病某些病理状态的指标。

Thyrotrotropin-releasing hormone(TRH) may play a role in regulating eating behavior, body temperature and conscious status. On the other hand, Histidyl-proline diketopiperazine, Cyclo(His-Pro), is known as endogenous metabolite of TRH.An Attempt was made to elucidate the nature of pyroglutamate aminopeptidase (pGlup) which converted TRH to Cyclo(His-Pro) endogenously.The results obtained were as follows:1. pGlup activitiy was determined by using pyroglutamy 1-4-methy lcoumarinyl amide as the substrate. 2. The purification of pGlup was performed by applying bovine amd rat brain homogenate on Sephacryl S-200 and GF-250 (HPLC). The molecular weight of pGlup protein was approximately 380000. 3. Radioimmunoassay of pGlup protein was established in our laboratory, using antibody to purified enzyme protein. 4. The distribution of pGlup in the rat brain showed that this enzyme protein was particularly rich in cerebellum and hypothalamus. 5. The positive correlation between brain pGlup concentration and Cyclo (His-Pro) during the developmental process of the rat was observed. 6. There was no difference in the circulating pGlup between patients with thyroid dysfunctio and normal subjects. 7. Some of patients with amyotrophic lateral sclerosis showed elevated pGlup level in the cerebrospinal fluid.The present results suggest that pGlup may be one of the important factor in regulating brain Cyclo(His-Pro) content. In addition, pGlup determination in the blood and cerebrospinal fluid of the patients may be an indicator of some pathological conditions of the diseases.