Cysteine-induced H2S emission, ATP depletion, and membrane electrical responses in oat coleoptiles |
| |
Authors: | Thomas B Kinraide Thomas E Staley |
| |
Institution: | Appalachian Soil and Water Conservation Research Lab., Agricultural Research Service, United States Department of Agriculture, P.O. Box 867, Beckley, WV 25802-0867, U.S.A. |
| |
Abstract: | Incubation of oat ( Avena sativa L. cv. Victory) coleoptile segments in 4 m M L-cysteine reduced the tissue ATP level to 42 nmol ( g fresh weight)?1 (35% of normal) over a 2 h period. Emissions of H2S accompanied this depletion in ATP suggesting an H2S production by desulfhydration of cysteine similar to that reported in other plants. Additions of exogenous H2S to the sections also caused ATP depletion. Aminooxyacetate, an inhibitor of cysteine desulfhydrase (EC 4.4.1.1), eliminated the cysteine-induced H2S emission and the ATP depletion. Prolonged exposure to cysteine depressed the electrical polarity of the cell membrane from – 116 mV to –85 mV. That and other electrical responses appear to reflect a reduced capacity for ATP-dependent H+ extrusion. These effects should be taken into account whenever cysteine is used in physiological experiments. |
| |
Keywords: | Amino acid aminooxyacetate sulfide transport |
|
|