An enzyme with fatty acid ␣-oxidation activity (49 nkat mg Ϫ1 ; substrate: lauric acid) was purified from germinating pea (Pisum sativum) by a five-step procedure to apparent homogeneity. The purified protein was found to be a 230-kD oligomer with two dominant subunits, i.e. a 50-kD subunit with NAD ϩ oxidoreductase activity and a 70-kD subunit, homolog to a pathogen-induced oxygenase, which in turn shows significant homology to animal cyclooxygenase. On-line liquid chromatography-electrospray ionization-tandem mass spectrometry revealed rapid ␣-oxidation of palmitic acid incubated at 0°C with the purified ␣-oxidation enzyme, leading to (R)-2-hydroperoxypalmitic acid as the major product together with (R)-2-hydroxypalmitic acid, 1-pentadecanal, and pentadecanoic acid. Inherent peroxidase activity of the 70-kD fraction decreased the amount of the (R)-2-hydroperoxy product rapidly and increased the level of (R)-2-hydroxypalmitic acid. Incubations at room temperature accelerated the decline toward the chain-shortened aldehyde. With the identification of the dual function ␣-dioxygenase-peroxidase (70-kD unit) and the related NAD ϩ oxidoreductase (50-kD unit) we provided novel data to rationalize all steps of the classical scheme of ␣-oxidation in plants.Fatty acid hydroperoxides are reactive intermediates in the oxylipin pathways of fatty acid oxygenation in plants and fungi

The substrate selectivities of the α oxidation of saturated, unsaturated, and heteroatom-containing (oxygen, sulfur) carboxylic acids 1 by the enzyme extract of peas (Pisum sativum) indicate that this biotransformation proceeds highly enantioselectively. For the first time, the synthesis of optically pure 2-hydroxy acids 2 has been achieved on the semipreparative scale (1 mmol) by α hydroxylation of long-chain carboxylic acids with molecular oxygen, catalyzed by the α oxidase of peas. For derivatives with sulfur atom in the chain, no sulfoxidation is observed. The functionalities (carbon double and triple bonds, oxygen, and sulfur atoms) must be at least three carbon atoms away from the carboxylic acid group to achieve efficient asymmetric hydroxylation. The absolute configuration of the 2-hydroxy acids 2 was assigned by comparison of the gas-chromatographic data with that of authentic reference compounds and by application of the exciton-coupled-circular-dichroism (ECCD) method. This unprecedented asymmetric biocatalytic methodology should be valuable for the preparation of enantiomerically pure (R)-2-hydroxy acids.

This work is the second part of a milk study evaluating the effect of package light transmittance on the vitamin content of milk, in this case on UHT whole milk. The milk was stored at three different light intensities in polyethylene terephthalate (PET) bottles with varying light transmittance as described by Saffert et al. (2006). Changes in the vitamin A, B 2 and D 3 content were monitored over a storage period of 12 weeks at 23°C. Losses in vitamins A and B 2 were most pronounced in completely transparent PET bottles exposed to the highest light intensity. In these bottles, a reduction of the light intensity reduced the vitamin A loss from 88 to 66%, while in the case of vitamin B 2 the complete decomposition was just delayed from 4 to 8 weeks storage. The vitamin D 3 losses in clear PET bottles were almost independent of the light intensity. For pigmented PET bottles, the impact of package light transmittance and light intensity differed for each vitamin. An increase in package light transmittance and light intensity was found to be most decisive for vitamin B 2 stability. In the case of vitamin D 3 , only the increase in light intensity was found to be of relevance, whereas for vitamin A stability the influence of increased package light transmittance and light intensity could not be clearly observed. In dark-stored 'control' samples, the analysed vitamins were almost stable.

This work is the third and last part of a milk study evaluating the effect of package light transmittance on the vitamin content of milk, in this case on fortifi ed UHT low-fat milk. The milk was stored under light with an intensity of 700 lux in polyethylene terephthalate (PET) bottles with varying light transmittance to monitor the changes in the vitamin A, B 2 and D 3 contents over a storage period of 12 weeks at 23°C. Milk packed in pigmented PET bottles with the lowest light transmittance, which was stored in the dark under the same experimental conditions, served as the 'control' sample. In clear PET bottles, a reduction of 93% of the initial content was observed for vitamin A and 66% for vitamin D 3 , while the vitamin B 2 content was completely degraded. In all pigmented PET bottles, the vitamin retention was only slightly higher; the losses ranged between 70 and 90% for vitamin A, between 63 and 95% for vitamin B 2 , and between 35 and 65% for vitamin D 3 depending on the pigmentation level. In the dark-stored 'control' sample, a 16% loss could be observed for vitamin A, while the level of vitamins B 2 and D 3 remained almost stable.