UV-B Radiation Mediated Alterations in the Nitrate Assimilation Pathway of Crop Plants 2. Kinetic Characteristics of Nitrite Reductase |
| |
Authors: | Balakumar T. Sathiameena K. Selvakumar V. Ilanchezhian C. Murugu Paliwal K. |
| |
Affiliation: | (1) Centre for Plant Biochemistry and Molecular Biology, Department of Botany, The American College, Madurai, 625 002, India |
| |
Abstract: | Cowpea [Vigna unguiculata (L.) Walp. cv. Co 4] seedlings were subjected to a weighted irradiance of 3.2 W m-2 s-1 of biologically effective ultraviolet-B radiation (UV-B, 280–320 nm) and the changes in the kinetic and other characteristics of nitrite reductase (NiR) were recorded. The activity of NiR was hampered by 19 % under UV-B irradiation compared to the control. The UV-B treated plants required higher concentrations of nitrate for the induction of NiR synthesis than the controls. The NiR activity decay kinetics showed that the UV-B treatment significantly lowers the t1/2 of the enzyme, thereby indicating a reduced rate of enzyme turnover. The comparison of kinetic characteristics of nitrate reductase (NR) and NiR under UV-B treatment showed that NiR was not so sensitive to UV-B radiation as NR. As shown by enzyme turnover rates, NiR extracted from plants irradiated by UV-B in situ was less sensitive to UV-B radiation than the enzyme extract subjected to in vitro UV-B irradiation. Though NiR was less damaged by UV-B treatment than NR, subtle changes occurred in its kinetic characteristics. This revised version was published online in June 2006 with corrections to the Cover Date. |
| |
Keywords: | nitrate reductase nitrite reductase enzyme induction and kinetics Vigna unguiculata |
本文献已被 SpringerLink 等数据库收录! |