Premium
Degradation of Luteinizing Hormone‐Releasing Hormone by Neuroblastoma Cells and Their Membrane: Evidence for the Involvement of a Thiol Protease and Angiotensin‐Converting Enzyme
Author(s) -
Yokosawa Hideyoshi,
Fujii Yurika,
Ishii Shinichi
Publication year - 1987
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1987.tb13161.x
Subject(s) - protease , thiol , enzyme , chemistry , biochemistry , cleavage (geology) , angiotensin ii , luteinizing hormone , hormone , biology , receptor , paleontology , fracture (geology)
Luteinizing hormone‐releasing hormone was degraded by cells of the N‐ I8 line of mouse neuroblastoma and their membrane. Cleavage products were separated by HPLC and identified by amino acid analysis. Fragments (1‐3), (4‐5), and (6‐10) were major cleavage products. All the products increased in level as a function of time except for fragment (1‐9, which increased in amount only during a short incubation time and then decreased. The accumulation of fragment (1‐5) was increased in the presence of captopnl or EDTA, whereas that of fragments (1‐3) and (4‐5) decreased inversely. On the other hand, the generation of either fragment (1‐3) or (4‐5) was stimulated by the presence of C1‐. The results suggest that the conversion of fragment (1‐5) into fragments (1‐3) and (4‐5) is catalyzed by angiotensin‐converting enzyme. p‐Chloromercuribenzoate inhibited the formation of fragment (1‐5), a result suggesting the involvement of a thiol protease in this formation. Thus, the degradation of luteinizing hormone‐releasing hormone by neuroblastoma cells and their membrane seems to take place mainly through the cleavage of the Tyr 5 ‐Gly 6 bond by a thiol protease, followed by the release of the dipeptide Ser‐Tyr from the liberated fragment (1‐5) by angotensin‐converting enzyme. It is further suggested that the thiol protease and angiotensin‐converting enzyme are also responsible for the initial minor cleavages of the Gly 6 ‐Leu 7 bond and the Trp 3 ‐Ser 4 bond, respectively.