Harold E. Pattee

Lipoxygenase isozymes of peanut.

Lipoxygenase was isolated and partially purified from peanut seed by ammonium sulfate precipitation, gel filtration, and ion exchange column chromatography. Three isozymes of lipoxygenase were identified. Two had pH optima of 6.2, and the other an optimum of 8.3. Molecular weight of each isozyme was 7.3×104, as determined by gel filtration. The alkaline optimum isozyme was not inhibited by NaCN and was inhibited by CaCl2 except at very low concentrations. The acid optimum isozymes were inhibited by NaCN and were stimulated by CaCl2 concentrations up to ca. 0.7 mM.

Characterization of peanut oil tricacyglycerols by HPLC, GLC and EIMS

Twenty-three peanut oil triacylglycerols have been characterized by liquid chromatography, gas chromatography and electron impact mass spectrometry. High resolution was achieved using two 8-cm × 6.2-mm reverse phase columns in series, and 20 of the triacylglycerols were separated in an analysis time of less than 45 min. Triacylglycerols were identified by analyzing each liquid chromatography fraction for carbon number, fatty acid composition and mass fragmentation pattern. The combined application of these methods permitted the identification of triacylglycerols representing combinations of all of the fatty acids present in peanut oil.

Anatomical Changes During Ontogeny of the Peanut (Arachis hypogaea L.) Fruit: Mature Megagametophyte through Heart-Shaped Embryo

Correlative light (LM) and scanning electron microscopy (SEM) of the same microtomed section was used to investigate components within the embryo sac of Arachis to the heart-shaped embryo phase of development. Morphometric data on the locule, ovule, embryo sac, and proembryo show that they reach maximum size during aerial development ca. 5 days after anthesis. After the onset of peg elongation, these components contract in size, and the apical locule and its components contract more than the basal. At the time of maximum aerial size, the proembryo is in the eight-cell stage and remains at that stage until the peg tip penetrates the soil surface. The first observed changes in the proembryo on reinitiation of growth is the swelling of the two basal tiers of cells from which the suspensor forms. Correlative LM and SEM of endosperm show physical contacts, in the form of cytoplasmic strands, between the connective cell layer at the base of the proembryo and the free-nuclear endosperm. These cytoplasmic strands are also layered against the integumentary tapetum and extend to the chalazal end of the embryo sac. These connections may have a role in the supply of nutrients to the developing embryo.

Peanut alkaline lipase.

Peanut alkaline lipase, (glycerol ester hydrolase EC 3.1.1.3), pH optimum 8.5, was isolated from acetone powders prepared from developing and germinated peanut seed (Arachis hypogaea L. var. NC-2). Enzyme activity/seed increased in successive developmental stages. The course of the hydrolytic reaction was linear with regard to enzyme concentration and all times tested up to periods exceeding 60 min. Km for the reaction was determined to be 2.6×10−4M. Molecular weight of peanut lipase, as estimated by Sephadex gel filtration and sodium dodecyl sulfate gel electrophoresis, was ca. 55,000.

Isolation of isomeric hydroperoxides from the peanut lipoxygenase- linoleic acid reaction

Hydroperoxides were isolated from the peanut lipoxygenase-linoleic acid reaction mixture and were separated as their methyl esters by high performance liquid chromatography. Mass spectrometry and infra-red analysis indicated the isolated hydroperoxides to be 13-hydroperoxy-cis-9,trans- 11-octadecadienoic acid; 13-hydroperoxy-trans- 9,trans- 11-octadeca-dienoic acid; and 9-hydroperoxy-trans-l0,trans- 12- octadecadienoic acid. The percentages of the hydro-peroxides in the reaction mixture were 72.8%, 3.6%, and 23.6% under the conditions used. 1 Paper No. 4973 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, NC 27607.

Changes in carotenoid and oil content during maturation of peanut seeds

To understand the changes in the color of peanut oil during maturation of the seeds, measurements were made of carotenoid and oil contents per kernel and carotenoid concentration of extracted peanut oil between the 4th and 12th weeks from pegging. Initially carotenoid concentration in the oil declined rapidly followed by a 50% decline between the 6th and 12th week. Changes in the carotenoid content and oil content of the peanut kernel indicated that the decrease in carotenoid concentration was due to a dilution produced by the rapid increase in oil content. Evidence is presented to indicate that the carotenoids are in areas separated from the oil containing spherosomes of the peanut kernel.

Calcium activation of peanut lipoxygenase

Peanut lipoxygenase isozyme 1 (pH optimum, 8.3) was strongly activated by 0.5–1.0 mM Ca++, and the rate of activation was maximum when the ratio of substrate to Ca++ was ca. 2∶1. Peanut lipoxygenase isozymes 2 and 3 (pH optima, 6.2) were activated by calcium but did not have an optimum level of activity. Calcium differentially activated peanut lipoxygenase causing the rate of pentane production to increase much more rapidly than the rate of oxygen consumed by the enzyme reaction. At pH 6.2, in the absence of calcium, the percentages of the hydroperoxide isomers produced by peanut lipoxygenase were 74.9% 13-hydroperoxycis-9,trans-11-octadecadienoic acid (13 LOOHcis-trans), 2.6% 13-hydroperoxytrans-9,trans-11-octadecadienoic acid (13 LOOHtrans-trans) and 22.5% 9-hydroperoxy 10, 12-octadecadienoic acid (9 LOOH). The presence of 1 mM Ca++ at pH 6.2 did not significantly affect the percentage distribution of the hydroperoxides produced. However, at pH 8.3, the percentage distribution of hydroperoxides produced was 45.2% 13 LOOHcis-trans, 10.9% 13 LOOHtrans-trans and 43.9% 9 LOOH in the absence of Ca++ and 57.0% 13 LOOHcis-trans, 8.0% 13 LOOHtrans-trans and 35.0% 9 LOOH in the presence of 1 mM Ca++.

Aerobic pentane production by soybean lipoxygenase isozymes

The effects of oxygen on production of pentane and compounds absorbing at 234 nm and 285 nm by soybean lipoxygenase isozymes I and II were examined in a model system. Aerobic conditions increased pentane production. Differences in dienone formation (A285) and diene conjugation (A234) indicate the reaction sequences of the 2 isozymes are not the same.

Carotenoid pigments of peanut oil

A method for analysis of carotenoid pigments in peanut oil is described. The major carotenoid pigments found in peanut oil were beta-carotene and lutein. A sample of oil from immature peanuts contained 60 µg of beta-carotene and 138 µg of lutein per liter of oil. The total carotenoid concentration in oil from mature peanuts appears to be less than 1 µg per liter of oil.

A preconcentration and subsequent gas liquid chromatographic analysis method for trace volatiles

A glass column containing a porous polymer was used to concen-trate headspace volatiles from enzymatically mediated reactions and inserted directly into the injection port of a gas liquid chromatog-raphy (GLC) for elution and separation of adsorbed volatiles. The polymer column was placed in an entrainment system attached to a water aspirator at 30 psi to collect volatiles produced by the en-zymatic reaction. A useful chromatogram was obtained from 1 g of raw material by this method. Volatiles collected in this manner could be stored on the polymer matrix at ambient temperatures without deleterious effects for subsequent GLC analysis. Multiple columns of the same or different trapping material could also be used in the entrainment system.