Canadian Forest Service Publications

Measurement and some aspects of regulation of initial and total Ribulose-1,5-biphosphate carboxylase/oxygenase activity in Douglas-fir. 1991. Mitchell, A.K.; Hinckley, T.M. Photosynthetica 25(3): 385-394.

Year: 1991

Issued by: Pacific Forestry Centre

Catalog ID: 3141

Language: English

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Abstract

A technique was developed to estimate initial and total ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activity in crude extracts from Douglas-fir [Pseudotsuga menziesii Mirb. (Franco)]. Extraction of sufficient RuBPCO to estimate initial activity required grinding the leaves in liquid nitrogen prior to homogenizing them in a buffer containing a detergent and a suite of protective agents. Interactions between Mg+2 and CO2 in the buffer necessitated its preparation CO2-free. Extraction buffer pH affected estimates of initial activity more than total activity. Regulation of Douglas-fir RuBPCO activity was primarily by carbamylation. Comparison of total activity in light and dark indicated CAlP was not a major regulatory mechanism in Douglas-fir. Shoot phenology had no significant effect on either initial or total activity in 1-year-old leaves. Temperature did not affect total activity but initial activity significantly increased between 5 and 15°C in spring and between 15 and 25°C in summer.