Heat modification of ribulose-1,5-bisphosphate carboxylase/oxygenase by temperature pretreatment of wheat (Triticum aestivum L.) seedlings

Abstract

The effect of low-, ambient- and high-temperature pretreatments (48 h at 4° C, 20° C or 36° C) of wheat seedlings (spring wheat Triticum aestivum L., cv. Kolibri) on the solubility properties of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCase; EC 4.1.1.39) was studied. The extractable protein moiety of heat-pretreated plants exhibited increased solubility in dilute buffer (50 mM k-phosphate, pH 6.8), compared with protein extracted from 4° C- or 20° C-plants. The salting-out characteristics for ammonium-sulfate precipitation confirmed this finding since a delayed precipitation of extractable protein from 36°C-plants was observed. Using polyacrylamide gel electrophoresis, the in-vivo temperature-induced differences in protein solubility could be traced back to a change in the solubility of RuBPCase. The RuBPCase was purified from wheat seedlings, and the purified enzyme also exhibited differential solubility. In order to evaluate this further, purified RuBPCase was subjected to probing for conformational properties. A decrease of fluorescence of the RuBPCase 1-anilino-8-naphtalene sulfonate complex revealed that the RuBPCase from 36° C-plants had a more hydrophilic protein surface. Titration of the sulfhydryl groups of native RuBP-Case with 5,5'-dithiobis (2-nitrobenzoic acid) pointed to a reduced accessibility of the R-SH groups in the case of the 36° C-type of RuBPCase. The large subunit of RuBPCase from 4° C/20° C-plants tended to give rise to an artificial lower-molecular-weight polypeptide which could not be found in crude or purified RuBPCase from heat-pretreated wheat seedlings.

Ribulose‐l,5‐bisphosphate carboxylase activity and influence of air pollution in spruce

“…2). Using purified RuBP carboxylase from wheat leaves (Weidner and Fehling 1985) as an internal standard, we could demonstrate that the level of enzyme activity, attainable by the extraction procedure used here agrees well with the in vivo total RuBP carboxylase activity present in the spruce needles: The mixing experiment (Tab. 2) yielded complete recovery of the added wheat enzyme activity.…”

“…Absorbance at 366 nm was recorded. The true concentration of the purchased RuBP preparation was controlled routinely, employing a purified RuBP carboxylase preparation (Weidner and Fehling 1985).…”

Changes in the Leaf Polypeptide Patterns of Barley Plants Exposed to Soil Flooding

“…Changes in the composition of proteins are important in the mechanism of adaptation to stress. Among these proteins, Rubisco is considered to be involved in the process of plant growth, development and productivity (Weidner and Fehling 1985).…”