6533b832fe1ef96bd129a169

RESEARCH PRODUCT

Preparation of extracts from mature spruce needles for enzymatic analyses

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description

It was possible to extract simultaneously several active enzymes involved in the carbohydrate or the amino acid metabolism from spruce needles [Picea abies (L.) Karst.] when a) a 100 mM Na-Pi buffer of pH 7.5 containing 5% PVPP and 0.5% Triton X-100 was used and when b) the resulting crude extracts were freed from lowmolecular-weight compounds by gel-chromatography using the separation medium Fractogel TSK HW-40. Besides Triton X-100, Triton X-305, Myrij-52 and Brij-35 were tested, but 0.5% Triton X-100 brought about the most active enzyme extracts. In crude extracts prepared from spruce needles during the early summer a high increase in absorbance at 334 nm was observed when the co-substrate NADP+ was added, thus making reliable spectrophotometric assays impossible. The interfering low-molecular-weight substances could be eliminated by gel chromatography. As separation media Bio-Gel P-6 DG, Sephadex G-25 m, Trisacryl GF 05 and Fractogel TSK HW-40 (F) were tested, with Fractogel yielding the highest activities. With the methods described in this paper the activities of the following enzymes were determined: glucose-6-phosphate dehydrogenase (EC 1.1.1.49), 6-phosphogluconate dehydrogenase (EC 1.1.1.44), glucose-6-phosphate isomerase (EC 5.3.1.9), shikimate dehydrogenase (EC 1.1.1.25), NAD+-malate dehydrogenase (EC 1.1.1.37), glutamate dehydrogenase (EC 1.4.1.2), aspartate aminotransferase (EC 2.6.1.1) and alanine aminotransferase (EC 2.6.1.2). The activities estimated for NAD+-malate dehydrogenase and 6-phosphogluconate dehydrogenase are in the range of those published for the needle enzymes of white spruce and Scots pine, respectively.