Open AccessOrnithine‐δ‐Transaminase Heterogeneity and Regulation
Author(s) -
Volpe Pietro,
Menna Tonino,
Pagano Giovanni
Publication year - 1974
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1974.tb03503.x
Subject(s) - transaminase , ornithine aminotransferase , ornithine , enzyme , kidney , biochemistry , biology , enzyme assay , chemistry , amino acid , endocrinology , arginine
In previous work it has been shown that end‐product regulation of ornithine‐δ‐transaminase in liver and kidney is mediated by different amino acids. It is now described that the enzyme purified from liver has different properties from that obtained from kidney with regards to temperature optimum, rate of heat inactivation and K m values. In HeLa cells grown in suspension and synchronized with thymidine, the “liver” form of ornithine‐δ‐transaminase appears in the S phase, while the “kidney” form of ornithine‐δ‐transaminase appears in the G 1 phase. In the G 2 phase there seems to be some mixing of the two enzyme forms. These data and reciprocal oscillation of proline content per cell and ornithine‐δ‐transaminase activity in the M and G 1 phases suggest that only in these stages of the cell cycle the enzyme is subjected to the same type of regulation as in kidney.