Glossy mutants of maize. VIII. Accumulation of fatty aldehydes in surface waxes of gl5 maize seedlings

In corn seedlings (Zea mays L.) homozygous for the mutation gl5, the surface waxes are characteristically altered. In this mutant the main wax constituents (83.5%) are aldehydes while in the normal waxes alcohols predominate (62.7%). Moreover, in the normal waxes aldehydes and alcohols are made up mainly of the C₃₂ term (99%), whereas in gl5 waxes the principal aldehyde is still C₃₂ (90.7%) but the free alcohol composition pattern is noticeably modified. Here the predominant terms are C₂₄, C₂₆, and C₂₈, with C₃₂ representing only 16.6% of the total. The results indicate that the mutant induces a block in the synthesis of fatty alcohols while accumulating fatty aldehydes, the substrates from which the alcohols originate.     

Microbial Oxidation of Hydrocarbons and Related Compounds by Whole-Cell Suspensions of the Methane-Oxidizing Bacterium H-2

Previously, a thermophilic obligate methane-oxidizing bacterium, H-2 (type I), was isolated in our laboratory. H-2 is a new type of methylotroph because of the G+C content of DNA; it uses both the ribulose monophosphate pathway and the serine pathway for carbon assimilation and possesses a new quinone. In addition, we found that resting cell suspensions of H-2 had the ability to oxidize a variety of compounds different from the other methane-oxidizing bacteria as follows. (i) C₁ to C₈n-alkanes are hydroxylated and further oxidized, yielding mixtures of the corresponding alcohols, aldehydes, acids, and ketones. Liquid alkanes are transformed through a different oxidative pathway from that of gaseous ones. (ii) Both gaseous (C₂ to C₄) and liquid (C₅, C₆) n-alkenes are oxidized to their corresponding 1,2-epoxides. (iii) Liquid monochloro and dichloro n-alkanes (C₅, C₆) are oxidized, yielding their corresponding acids or haloacids. (iv) Diethyl ether is oxidized to acetic acid; no ethanol and acetaldehyde are detected. (v) Cyclic and aromatic compounds are also oxidized. (vi) Secondary alcohols (C₃ to C₁₀) are oxidized to their corresponding methyl ketones.     

Production of Methyl Ketones from Secondary Alcohols by Cell Suspensions of C2 to C4n-Alkane-Grown Bacteria

Nineteen new C₂ to C₄n-alkane-grown cultures were isolated from lake water from Warinanco Park, Linden, N.J., and from lake and soil samples from Bayway Refinery, Linden, N.J. Fifteen known liquid alkane-utilizing cultures were also found to be able to grow on C₂ to C₄n-alkanes. Cell suspensions of these C₂ to C₄n-alkane-grown bacteria oxidized 2-alcohols (2-propanol, 2-butanol, 2-pentanol, and 2-hexanol) to their corresponding methyl ketones. The product methyl ketones accumulated extracellularly. Cells grown on 1-propanol or 2-propanol oxidized both primary and secondary alcohols. In addition, the activity for production of methyl ketones from secondary alcohols was found in cells grown on either alkanes, alcohols, or alkylamines, indicating that the enzyme(s) responsible for this reaction is constitutive. The optimum conditions for in vivo methyl ketone formation from secondary alcohols were compared among selected strains: Brevibacterium sp. strain CRL56, Nocardia paraffinica ATCC 21198, and Pseudomonas fluorescens NRRL B-1244. The rates for the oxidation of secondary alcohols were linear for the first 3 h of incubation. Among secondary alcohols, 2-propanol and 2-butanol were oxidized at the highest rate. A pH around 8.0 to 9.0 was found to be the optimum for acetone or 2-butanone formation from 2-alcohols. The temperature optimum for the production of acetone or 2-butanone from 2-propanol or 2-butanol was rather high at 60°C, indicating that the enzyme involved in the reaction is relatively thermally stable. Metal-chelating agents inhibit the production of methyl ketones, suggesting the involvement of a metal(s) in the oxidation of secondary alcohols. Secondary alcohol dehydrogenase activity was found in the cell-free soluble fraction; this activity requires a cofactor, specifically NAD. Propane monooxygenase activity was also found in the cell-free soluble fraction. It is a nonspecific enzyme catalyzing both terminal and subterminal oxidation of n-alkanes.     

Specific inhibition of alkane synthesis with accumulation of very long chain compounds by dithioerythritol, dithiothreitol, and mercaptoethanol in Pisum sativum

Sodium [1-¹⁴C]acetate and [1-¹⁴C]stearic acid were readily incorporated into hydrocarbons, secondary alcohols, wax esters, aldehydes, primary alcohols, and fatty acids in young pea leaves (Pisum sativum). Dithioerythritol, dithiothreitol, and mercaptoethanol (but not glutathione and cysteine) severely inhibited the incorporation of labeled acetate into alkanes and secondary alcohols with accumulation of label in wax ester and aldehyde fractions. Detailed radio gas-chromatographic analyses of the fatty acids of both the surface lipid components and internal lipids showed that dithioerythritol and mercaptoethanol specifically inhibited n-hentriacontane (C₃₁) synthesis and caused accumulation of C₃₂ aldehyde, suggesting that the inhibition was at or near the terminal step in alkane biosynthesis, presumably decarboxylation. Trichloroacetate, at a concentration that inhibited C₃₁ alkane synthesis but not the synthesis of alcohols (C₂₆ and C₂₈) specifically inhibited the formation of C₃₂ aldehyde but not that of the C₂₆ or C₂₈ aldehyde. From these results, it is concluded that the C₃₂ aldehyde is derived from the C₃₂ acyl derivative which is the precursor of C₃₁ alkane.     

Microbial oxidation of methanol: Properties of crystallized alcohol oxidase from a yeast, Pichia sp

Alcohol oxidase (alcohol:oxygen oxidoreductase) was crystallized from a methanolgrown yeast, Pichia sp. The crystalline enzyme is homogenous as judged from polyacrylamide gel electrophoresis. Alcohol oxidase catalyzed the oxidation of short-chain primary alcohols (C₁ to C₆), substituted primary alcohols (2-chloroethanol, 3-chloro-1-propanol, 4-chlorobutanol, isobutanol), and formaldehyde. The general reaction with an oxidizable substrate is as follows: Primary alcohol + O₂ → aldehyde + H₂O₂ Formaldehyde + O₂ → formate + H₂O₂. Secondary alcohols, tertiary alcohols, cyclic alcohols, aromatic alcohols, and aldehydes (except formaldehyde) were not oxidized. The K_m values for methanol and formaldehyde are 0.5 and 3.5 mm, respectively. The stoichiometry of substrate oxidized (alcohol or formaldehyde), oxygen consumed, and product formed (aldehyde or formate) is 1:1:1. The purified enzyme has a molecular weight of 300,000 as determined by gel filtration and a subunit size of 76,000 as determined by sodium dodecyl sulfate-gel electrophoresis, indicating that alcohol oxidase consists of four identical subunits. The purified alcohol oxidase has absorption maxima at 460 and 380 nm which were bleached by the addition of methanol. The prosthetic group of the enzyme was identified as a flavin adenine dinucleotide. Alcohol oxidase activity was inhibited by sulfhydryl reagents (p-chloromercuribenzoate, mercuric chloride, 5,5′-dithiobis-2-nitrobenzoate, iodoacetate) indicating the involvement of sulfhydryl groups(s) in the oxidation of alcohols by alcohol oxidase. Hydrogen peroxide (product of the reaction), 2-aminoethanol (substrate analogue), and cupric sulfate also inhibited alcohol oxidase activity.     

The alteration of intracellular enzymes. III. The effect of temperature on the kinetics of altered and unaltered yeast catalase

1. The very large increase in catalase activity (Euler effect) which follows treatment of yeast cells with CHCl₃, UV and n-propanol is accompanied by highly significant changes in kinetic properties. With respect to the enzymatic decomposition of H₂O₂, the thermodynamic constants of the activation process µ, ΔH‡, ΔS‡, ΔF‡, decrease, following treatment of the intracellular enzyme, by 4.5 kcal., 4.5 kcal., 10.1 e.u. and 1.7 kcal., respectively, all these differences being significant at the 1 per cent level. 2. Similar differences exist between the untreated, intracellular enzyme on the one hand, and the extracted yeast and crystalline beef liver catalases on the other. Significant differences in these thermodynamic constants do not exist among the treated intracellular, extracted yeast, and crystalline liver catalases. 3. These data provide unequivocal confirmation of the phenomenon of enzyme alteration reported previously, and confirm previous evidence that the extracted and crystalline enzymes have also undergone enzyme alteration and have properties which are identical with, or very similar to, those of the catalase altered in situ. 4. With respect to the process of heat destruction of catalase, the greatly diminished stability to heat of the altered enzymes, previously reported, has been confirmed. The thermodynamic constants of activation of this process have likewise changed following alteration, in the case of µ, ΔH‡, and ΔS‡ an increase of 20.6 kcal., 20.6 kcal., and 70 e.u., respectively, and of ΔF‡ a decrease of 2.8 kcal. 5. All these data have been shown to be consistent with, and in some cases predictable from, the interfacial hypothesis, which states that the unaltered catalase exists within the cell adsorbed to some interface, in a partially, but reversibly, unfolded configuration of relatively low specificity; enzyme alteration consists, in the case of catalase, of desorbing the enzyme from the interface into its rolled-up, soluble, highly specific configuration. While the interfacial hypothesis has successfully withstood this experimental attack, the present data do not provide its unequivocal proof, since they are consistent with any hypothesis of alteration in which the unaltered, intracellular enzyme is in a relatively disordered state by comparison to the altered enzyme. While evidence of an interfacial process in enzyme alteration has been adduced previously, critical proof of the interfacial hypothesis awaits creation of a model system, in which most of the aspects of intracellular alteration can be reproduced. 6. Certain of the changes in kinetic properties following alteration of the intracellular enzyme, such as increased activity and the modified energies and entropies of activation of both enzyme-substrate system and heat destruction of the catalase itself, might be explained by a decrease (two orders of magnitude) in the effective hydrogen ion concentration, allowing the intracellular enzyme to be brought to the same pH as the extracellular medium. If such a pH change does, in fact, occur, it is necessary to invoke the interfacial hypothesis to explain why the unaltered, intracellular enzyme is in equilibrium with a medium whose pH is approximately 2 units lower than that of the cytoplasm itself. 7. It is concluded that kinetic data of this kind may be used to shed light on the structure of a soluble, cytoplasmic enzyme, not attached to any of the formed elements within the cell, yet organized within it in a condition of relatively low structural specificity; further, that information obtained exclusively from a study of the kinetics of the extracted or crystalline enzymes may not, in the case of this enzyme, at least, be extrapolated to the same enzyme within the intact cell.     

Purification and characterization of constitutive polyethylene glycol (PEG) dehydrogenase of a PEG 4000-utilizing Flavobacterium sp. no. 203

Polyethylene glycol (PEG) 4000-utilizing bacterium no. 203 was identified as a Flavobacterium species. 2, 6-Dichlorophenol-indophenol (DCIP)-dependent PEG dehydrogenase was constitutively formed in nutrient broth, glucose and PEG media. However, the enzyme formation was repressed in the presence of an excess amount (over 0.25%) of PEG 400 or 1000. PEG dehydrogenase was purified approximately 34 fold by precipitation with ammonium sulfate, solubilization with benzalkonium chloride, chromatography with DEAE-Toyopearl 650 M and hydroxylapatite and gel filtration on Toyopearl HW-55. The molecular weight of the purified PEG dehydrogenase was calculated to be approximately 2.20 × 10⁵, a value which seemed to consist of four subunits with the same molecular weight of 5.70 × 10⁴. The enzyme was stable below 40°C and in the pH range of 7.0 and 8.0. The optimum pH and temperature of the activity were around 8.0 and 40°C, respectively. The enzyme reduced DCIP and coenzyme Q₁ and Q₂. PEG dehydrogenase showed activity toward various PEG molecules (dimer-PEG 20,000). The apparent K_m values for PEG 400, 1000, 4000 and 6000 were about 1.0, 1.7, 2.8 and 5.9 mM, respectively. The enzyme oxidized primary aliphatic alcohols of C₃–C₁₂, the corresponding aldehydes of C₃–C₇, aromatic alcohols and aldehydes, diols, etc. The enzyme was inactive on ethylene glycol, glycerol, secondary alcohols and sugar alcohols. The enzyme activity was strongly inhibited by sulfhydryl agents or heavy metals and 1, 4-benzoquinone. The purified enzyme showed absorption apectrum similar to that of PEG 6000 dehydrogenase which has already been reported to be a quinoprotein. The prosthetic group of the enzyme was extracted with methanol and identified as PQQ from its prosthetic group capability for glucose dehydrogenase and the fluorescence spectrum.     

Hydroxylation of n-alkanes to secondary alcohols and their esterification in the grasshopper Melanoplus sanguinipes

Labeled n-alkanes administered to the grasshopper $\text{Melanoplus}$$\text{sanguinipes}$ are hydroxylated at or near the middle of the carbon chain. The secondary alcohols formed are then esterified. Chain length specificity is evident in both the hydroxylation of n-alkanes and the esterification of secondary alcohols, with the shorter chain C₂₃, C₂₁, C₁₉, and C₂₅ compounds converted to secondary alcohol wax esters more readily than the longer chain C₂₇, C₂₉, and C₃₁ compounds. Secondary alcohols and ketones are not reduced to alkanes.     

Ketonic rancidity in coconut due to xerophilic fungi

A type of deterioration called ketonic rancidity occurred in coconut after inoculation with four xerophilic fungi, Eurotium amstelodami, E. chevalieri, E. herbariorum and Penicillium citrinum. The fungi were incubated at low water activity and oxygen tension. A homologous series of aliphatic methyl ketones and secondary alcohols C₅C₁₁ were isolated and identified in the rancid samples after fungal growth. Evidence is presented that odd numbered methyl ketones (C₅C₁₁) are derived from even numbered short chain fatty acids with one more carbon atoms than the ketones via a modified β-oxidation of the parent fatty acid. Heptan-2-one and heptan-2-ol are the main reaction products except in the case of E. herbariorum where even numbered hexan-2-one, hexan-2-ol, octan-2-one and octan-2-ol were produced. Other moulds grown on coconut under similar conditions—Aspergillus flavus Link and Chrysosporium farinicola (Burnside) Skou (C. fastidium Pitt)—did not cause ketonic deterioration.     

Composition and structure of secondary fatty alcohols and ketones,isolated from Pyrus malus skin wax

A homologous series of long-chain secondary fatty alcohols from C₂₁ to C₂₉ (C₂₉ being Predominant) has been isolated from the skin wax of a Bulgarian apple variety, Bouhavitsa. The alcohols were found only in a free state. Long-chain fatty ketones, with C₂₉ again markedly prevalent, have been isolated for the first time from the skin wax of this, and another variety, Tetovka. The C₂₉-ketone from both samples was identified by means of MS as nonacosan-10-one. A complete similarity has been found in the relative amounts of C₂₉ in the mixtures of secondary alcohols, ketones and paraffins.     

Identification and Characterization of the Butane-Utilizing Bacterium,Arthrobacter sp. PG-3-2, Harboring a Novel bmoX Gene

A bacterium, PG-3-2, capable of butane-utilization as a sole carbon source was isolated from Puguang oilfield in Sichuan Province, China and identified as Arthrobacter sp. by 16S rRNA gene sequence and morphology characteristics. Butane-saturated medium was defined as optimal for the growth of PG-3-2. Proliferation of PG-3-2 was enhanced at low butanol concentrations (≤50 mM) and repressed at high concentrations (≥100 mM). Growth of strain PG-3-2 was supported by alkanes from C₂ to C₁₀ (except pentane) and various carbon substrates including primary alcohols, secondary alcohols, carboxylic acids, aldehydes, ketones, but not methane or its oxidation products. The rate of butane degradation by PG-3-2 was relatively high during the lag phase and prophase of the exponential phase. A bmoX gene, which encodes the alpha hydroxylase subunit of butane monooxygenase, was amplified from the genome of this bacterium. Sequence analysis revealed a high level of homology with alkane monooxygenase, thus indicating the existence of a novel bmoX gene involved in the butane degradation pathway in this Arthrobacter strain.     

Expression of secondary alcohol dehydrogenase in methanogenic bacteria and purification of the F420-specific enzyme from Methanogenium thermophilum strain TCI

In four species of methanogens able to grow with secondary alcohols as hydrogen donors the expression and properties of secondary alcohol dehydrogenase (sec-ADH) were investigated. Cells grown with 2-propanol and CO₂ immediately started to oxidize secondary alcohols to ketones if transferred to new media. In the presence of H₂, such cells reduced ketones or aldehydes to alcohols. In the absence of H₂, aldehydes were dismutated (without growth) to primary alcohols and fatty acids. None of these reactions was catalyzed by cells grown with only H₂ and CO₂ at non-limiting concentration. This indicated an induction or derepression of sec-ADH by its substrate. Apparently, sec-ADH in all strains enabled not only the reduction of ketones or aldehydes, but also the dismutation of the latter. Sec-ADH was also expressed if strains were grown on H₂ and CO₂ in the presence of non-oxidizable, tertiary alcohols. Methanogenium thermophilum expressed sec-ADH even without added alcohol when H₂ became limiting. From this species, an F₄₂₀-specific sec-ADH was purified; the final gel filtration chromatography yielded a single protein peak that coincided with the activity. The enrichment was 12-fold, the activity recovery 26%. SDS polyacrylamide gel electrophoresis indicated that the enzyme was a homodimer with an apparent M _r of 79,000. At the pH optimum around 4.2, the specific activity for oxidation of 2-propanol (130 mM) and reduction of acetone (20 mM) was 176 and 110 mol/ min·mg, respectively (40°C). The apparent K _m for 2-propanol and acetone (with 15 M F₄₂₀) was 2.5 and 0.25 mM, respectively. Aldehydes also were reduced.Non-standard abbreviations ADH alcohol dehydrogenase - Bis-Tris bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane - F₄₂₀ N-(N-L-lactyl--L-glutamyl)-L-glutamic acid phosphodiester of 7,8-didemethyl-8-hydroxy-5-deazariboflavin-5-phosphate - Mb. Methanobacterium - Mg. Methanogenium - Ms. Methanospirillum - OD₅₇₈ optical density at 578 nm - SDS sodium dodecyl sulfate     

The composition of external lipids from adult whiteflies,Bemisia tabaci and Trialeurodes vaporariorum

The total surface lipids, including the wax particles, of the adult whiteflies of Bemisia tabaci and Trialeurodes vaporariorum were characterized. At eclosion, there were similar amounts of long-chain hydrocarbons, aldehydes, alcohols and wax esters. Within a few hours post-eclosion, long-chain aldehydes and long-chain alcohols were the dominant surface lipid components, C₃₄ on B. tabaci and C₃₂ on T. vaporariorum. Hydrocarbons, mainly n-alkanes, were minor components of the surface lipids. The major wax esters were C₄₆ on B. tabaci and C₄₂ on T. vaporariorum. The major acid and alcohol moieties in the wax esters of B. tabaci were C₂₀ and C₂₆, respectively, and of T. vaporariorum were C₂₀ and C₂₂, respectively. Both B. tabaci and T. vaporariorum had a minor wax ester composed of the fatty acid C_18:1 esterified to the major alcohols, C₃₄ and C₃₂, respectively. Bemisia were readily distinguished from Trialeurodes based on the composition of their wax particles and/or their wax esters; however, no differentiating surface lipid components were detected between biotypes A and B of B. tabaci.     

Epicuticular waxes of Sorghum and some compositional changes with plant age

Epicuticular wax from mature plants of Sorghum bicolor SD-102 was compared with that from panicles and seedlings of the same variety at the fourth-fifth leaf stage of growth. The composition of wax from SD-102 panicles was quite different from that of mature leaf blades and sheaths. Free fatty alcohols were the dominant class of wax from SD-102 seedlings and C₃₂ was the major homologue of alcohols and aldehydes. For comparison purposes, the epicuticular waxes from whole plants of two other S. bicolor varieties, Alliance A and Martin A, grown up to the tasseling stage, have been analysed. The major wax components were free fatty acids. The typical chain lengths of aldehydes, free alcohols and free fatty acids were C₂₈ and C_30.p-Hydroxybenzaldehyde was not a wax component of the studied varieties of sorghum.     

Conversion of Some Saturated Fatty Acids,Aldehydes, and Alcohols into γ- and δ-Lactones

A series or γ- and δ-lactones could be found in the thermal oxidative products of normal saturated acids, aldehydes, and alcohols (C₉, C₁₀, and C₁₂, respectively) heated at 180°C in the presence of 0.1% KMnO₄. Their lactones were identified by gas chromatography, infrared spectroscopy, and mass spectroscopy. And they could be detected also in the volatile compounds occurred by heating of C₁₀ acid, aldehyde, and alcohol mixed with pork fat. So it was expected that lactones in meat fat flavor described in the earlier papers could be secondary products converted from saturated acids, aldehydes, and alcohols formed by oxidative degradation of meat fats. This process was presumed to be one of the mechanisms of the lactone formation.

It was discussed that lactones might be derived through mono or dihydroperoxides of acids, aldehydes, and alcohols.     

Aliphatic alcohols and aldehydes of the honey bee cocoon induce arrestment behavior in Varroa jacobsoni (Acari: Mesostigmata), an ectoparasite of Apis mellifera

The ectoparasitic mite Varroa jacobsoni reproduces in the capped brood of the honey bees Apis cerana and Apis mellifera. Observations on the reproductive behavior of the mite have shown a well-structured spatial allocation of its activity using the bee or cell wall for different behaviors. The resulting advantages for the parasite of this subdivision of the concealed brood environment suggests an important role for chemostimuli in these substrates. Extracts of the European honey bee cocoons induce a strong arrestment response in the mite, as indicated by prolonged periods of walking on the extracts applied on a semipermeable membrane and by systematically returning to the stimulus after encountering the treatment borders. Two thin-layer chromatography fractions of the cocoon extract eliciting arrestment were found to contain saturated C₁₇ to C₂₂ primary aliphatic alcohols and C₁₉ to C₂₂ aldehydes. We analyzed extracts of the cocoon and different larvae, pupae, and adults of both worker and drone A. mellifera to determine the relative amounts of these chemostimuli in the different substrates employed by Varroa. Both aldehydes and alcohols were more abundant in the cocoon than in the cuticle of adult or developing bees. Mixtures of the aliphatic alcohols and aldehydes at the proportions found in the cocoons acted synergistically on the arrestment response, but this activity disappeared when mixed in equal amounts. When these oxygenated chemostimuli were mixed with C₁₉ to C₂₅ alkanes at the proportions found in the cocoon extract, we observed a significantly lower threshold for the chemostimulant mixture. These results indicate how Varroa may use mixtures of rarer products to differentiate between substrates and host stages during its developmental cycle within honey bee brood cells. Arch. Insect Biochem. Physiol. 37:129–145, 1998. © 1998 Wiley-Liss, Inc.     

The role of alcohols in pheromone biosynthesis by two noctuid moths that use acetate pheromone components

Primary alcohols varying in chain length from C₁₃ to C₁₆, and in number, position, and geometric configuration of double bonds, were applied in dimethyl sulfoxide to the surface of the female sex pheromone glands of Heliothis subflexa (Gn.) and Hydraecia micacea (Esper). Capillary gas chromatographic analysis of extracts of the treated glands indicated that the alcohols were converted to the corresponding aldehydes by H. subflexa females and to the acetates by H. micacea females. Conversions of the alcohols showed no preferences for molecular weight, number, position, or geometry of the double bonds in either species. Application of the acetates of the primary alcohols to the gland surface of H. subflexa females resulted in the production of both the corresponding alcohols and aldehydes, while neither alcohols nor aldheydes were produced when acetates were applied to the glands of H. micacea. In addition, application of the acetates to the gland surface of Heliothis virescens (F.) resulted in the production of both the corresponding alcohols and aldehydes. However, no evidence was found to indicate that acetates are ever produced by the pheromone gland of females of H. virescens.     

The hydrolysis of the alkenyl group from enthanolamine-plasmalogen by oligodendroglial cell-enriched fractions

The rate of hydrolysis of the 1-0-alkenyl group of sn-1-alk-1′-enyl-2-acyl-glycerylphosphorylethanolamine (alkenyl, acyl-GPE; ethanolamine plasmalogen) by plasmalogenase is higher in oligodendroglial cell-enriched fractions from bovine brain compared with fractions enriched in neuronal perikarya and astroglia. The distribution of plasmalogenase activity in membrane fractions isolated from bovine oligodendroglia has been compared with that of ‘marker’ enzymes. The highest specific activity was in a fraction enriched in plasma membranes, whilst most activity was recovered in an endoplasmic reticulum membrane fraction. In bovine oligodendroglial cell homogenates, the enzyme had a neutral pH optimum, had no requirement for divalent cations and its activity towards 1-alkenyl-GPE (lysoplasmalogen) was half that with alkenyl, acyl-GPE. C₁₆ alkenyl groups were hydrolysed more rapidly than C₁₈ alkenyl groups. With ³H-labelled alkenyl, acyl-GPE as substrate, radioactivity in released aldehydes appeared in fatty acids esterified in phospholipid while the oxidation of fatty aldehydes was blocked by the addition of NADH. An NAD-dependent aldehyde dehydrogenase was found to be present in oligodendroglia which exhibited highest activity towards C₁₄C₁₈ aldehydes (K_m, 2 μM).     

Absence of long chain aldehydes in the wax of the Glossy II mutant of maize

Wax from the glll mutant of maize lacks aldehydes, which constitute 20 % in the normal genotype. The absence of aldehydes is not associated with a block in the synthesis of alcohols. Moreover in contrast to the wild type, glll wax is characterized by a higher content of C₁₆ and C₁₈ free acids, with a clear defect in the synthesis of C₂₄, C₂₆ and C₂₈ homologues. The results from this study are taken as evidence that the wild type elongation-decarboxylation I (EDI) pathway, leading to the synthesis of all the wax classes of compounds except esters, may be split into an early (EDIa) and a late (EDIb) group of reactions. Mutant glll is apparently defective at the EDIa, governing the synthesis of C₂₄–C₂₈ fatty acyl chains.