Low Molecular Weight Acids Research Articles

Advances in understanding the podzolization process resulting from a multidisciplinary study of three coniferous forest soils in the Nordic Countries

Geochemical, mineralogical, micromorphological, microbiological, hydrochemical and hydrological joint investigations were performed at two coniferous podzolic sites in the north of Sweden and at one in the south of Finland. Mycorrhizal fungi were found to create numerous pores (3–10-μm diameter) in many weatherable mineral grains in the eluvial (E) horizon. During the growing season, identified low molecular weight (LMW) organic acids such as citric, shikimic, oxalic and fumaric acids comprised 0.5–5% of the DOC and 0.5–15% of the total acidity in soil solutions. Between 20% and 40% of the dissolved Al was bound to the identified LMW organic acids. Mineral dissolution via complexing LMW acids, probably exuded in part by the mycorrhiza hyphae, is likely to be a major weathering process in podzols. We found no evidence for a decreasing C/metal ratio of the migrating organo-metal complexes that could explain the precipitation of secondary Fe and Al in the illuvial (B) horizon. Instead, microbial degradation of organic ligands resulting in the release of ionic Al and Fe to the soil solution may be an important process facilitating the formation of solid Al–Si–OH and Fe–OH phases in the podzol B horizon. However, within the B horizon transport as proto-imogilite (PI) sols might be possible. In the B horizon, the extractable Al and Fe was predominantly inorganic. The large specific surface area (SSA) removable by oxalate extraction, the high point of zero charge salt effect (PZSE), the low cation exchange capacity (CEC) and the high sulphate exchange capacity (SEC), pointed to the presence of short-range ordered variable charge phases. Imogolite type material (ITM) was indeed identified in all B horizons by IR spectroscopy and crystalline imogolite was found in the deep B horizon of one profile. Mössbauer spectroscopy indicated that Fe in the form of ferrihydrite was formed by intergrowth with an Al–Si–OH phase. The high amounts of Fe and Al transported from the O to the E horizon indicate that there could be an upward transport of these elements before they are leached to the B horizon. We hypothesize that the LMW Al complexes are transported by hyphae to the mor (O) layer, partly released and subsequently complexed by high molecular weight (HMW) acids.

Equilibrium models of aluminium and iron complexation with different organic acids in soil solution

The percentage of Al and Fe bound to identified low molecular weight (LMW) organic acids and phosphate in soil solution was calculated using a chemical equilibrium model. The highest fractions were obtained for the O1 horizon solutions with median values between 38–49% for Al and 18–29% for Fe. Generally the percentage declined in the deeper horizons Acceptable agreement with experimental values using ultrafiltration (<1000 D) was found especially for the spring and summer samplings. In the autumn samples, larger deviations between the modelled and ultrafiltered fractions were found. The major part of the remaining Al and Fe in solution was calculated to be bound to undefined organic acids most likely of higher molecular weight. Speciation studies of some individual organic acids are presented. Citric acid proved to be the most important complex former of the LMW acids in the O and E horizons while oxalic acid was dominant in the B horizon solutions. The total level of organic complexation of Al, Fe, Ca and Mg was also studied. It was found that >85% of the Al and >95% of the Fe were organically bound. The opposite was seen for Ca and Mg for which >85% was modelled to occur as inorganic ions. The modelling results support the theory that LMW organic acids contribute to the translocation of Al and Fe in the podzolization process.

Low molecular weight acid phosphatase/phosphotyrosyl protein phosphatase in the developing chick brain: partial characterization and levels during development.

Low molecular weight acid phosphatase/phosphotyrosyl protein phosphatase is largely expressed in chick brain tissue during development. The enzyme was purified from brain extract prepared from 19-day-old chick embryos and from adult chickens using ammonium sulfate fractionation, gel filtration on Sephadex G-75 and two DEAE-Cellulose ion-exchange chromatography steps. The purified enzymes from embryo and adult chick brains show identical molecular weight values (about 18-20 kDa) and biochemical and structural properties such as substrate specificity, sensitivity to inhibitors, and number of free reactive sulphydryl groups. These data suggest that they are the same enzyme protein. Although the total acid phosphatase activity does not change appreciably during development, the activity associated with the low molecular weight acid phosphatase/phosphotyrosyl protein phosphatase markedly increases after birth and reaches the adult values within the first week of life. Taken together, our results suggest an involvement of the low molecular weight acid phosphatase/phosphotyrosyl protein phosphatase in postnatal development and maturation of chick brain tissue. The variations in tyrosine phosphorylation profile of chick brain polypeptides analyzed by Western blotting at the same developmental stages are also reported.

Chemical Characterization of Reproduction Cork from Spanish Quercus Suber

The chemical composition of Quercus suber reproduction cork was studied in planks from three different trees at different stages of their industrial processing and in samples collected in seven locations in the three main Spanish production areas. Extracts in chloroform, methanol and water, neùtral and acid fractions of waxes, suberin, lignin, holocellulose and pentosans, and polyphenols (low molecular weight polyphenols and tannins), were quantified. Suberin was the main component in all the samples, followed by lignin and holocellulose in lower concentrations. The most affected variables throughout the industrial processing were: lignin, chloroform and water extracts and the acid fraction of waxes. These variables did not allow one to distinguish the studied trees, which are differentiated by the percentages of methanol extracts, the tannic fraction of polyphenols, the free of suberin residue and the holocellulose content. Four variables were selected as those which provided the greatest discrimination among provenances: methanol extract, low molecular weight polyphenols, desuberinized residue and acid fraction of waxes. However, the studied populations can not be clearly distinguished by their chemical composition and no relationship was found between geographical proximity of their provenances and chemical resemblance.

Study on Migration Behavior of Organic Acids of Low Molecular Weights in Capillary Zone Electrophoresis

An equation to describe the migration behavior of organic acids of low molecular weight in capillary zone electrophoresis(CZE) is derived based on the knowledge of the electric chemistry and the theory of acid-base equilibrium. The equation can be readily applied to predicted the migration order for organic acids in CZE. The predictions using the equation agree well with the experiment results by us and other workers. Also, the equation may be used for the estimation of electroosmotic mobility and the calculation of the dissociation constants for acids.

Induction of a Germination Specific, Low Molecular Weight, Acid Phosphatase Isozyme with Specific Phosphotyrosine Phosphatase Activity in Lentil (Lens esculenta) Seeds

A germination specific isozyme of acid phosphatase (EC 3.1.3.2) hydrolysingO-phospho-L-Tyrosine, pH optima 5.5 is induced in lentil seeds. When seeds at 0 h, 24 h and 36 h of germination are electrophorezed, native PAGE on specific enzyme staining shows several constitutive isozymes of acid phosphatases. At 48 h, an isozyme is induced which gradually decreases and then disappears at 108 h of germination. The short lived, induced isozyme is present in the embryo and seed-coat but not in the plumule and the radical. Induction of this isozyme is inhibited by cycloheximide and actinomycin-D and increased by plant growth regulators such as heteroauxin and gibbrellic acid treatment during germination. The induced isozyme is a single 30 kD polypeptide, with subunit molecular mass of 25 kD, shows activity forO-phospho-L-Tyrosine. It is strongly inhibited by vanadate (μM), molybdate, tungustate as also by iodoacetate,p-chloromercuribenzoate and diethylpyrocarbonate. This study shows for the first time that the germination induced low molecular weight Acid phosphatase is a Tyrosine phosphatase super family class IV enzyme, having a role in cellular differentiation and development during seed germination.

Phosphotyrosine-protein-phosphatase and diabetic disorders. Further studies on the relationship between low molecular weight acid phosphatase genotype and degree of glycemic control.

We have studied a new sample of 276 NIDDM patients from the population of Penne (Italy). Comparison of the new data with those of 214 diabetic pregnant women from the population of Rome reported in a previous paper has shown that the pattern of association between low molecular weight acid phosphatase genotype and degree of glycemic control is similar in the two classes of diabetic patients.Among nonobese subjects the proportion of ACP1*A (the allele showing the lowest enzymatic activity) is lower in diabetic patients with high glycemic levels (mean value greater than 8.9 mmol/l) than in diabetic patients with a low glycemic level (mean value less than 8.9 mmol/l). Among obese subjects no significant association is observed between glycemic levels and ACP1. Among nonobese subjects the concentration of f isoform of ACP1 is higher in patients showing a high glycemic level than in patients showing a low glycemic level. No significant difference is observed for s isoform.

Acid phosphatases of Esox lucius: tissue distribution and partial characterization

The presence of different acid phosphatase classes was examined in organs and tissues of the fish Esox lucius. The enzymes were separated by Sephadex G‐200 column chromatography, and characterized as regards tissue distribution, molecular weight, metal ion activation, inhibition, pH optima, temperature sensitivity, rate of hydrolysis and substrate specificity. High and low molecular weight acid phosphatases as well as high and low molecular weight Zn2+‐dependent acid phosphatases were present in pike organs and tissues. In addition, their biochemical properties and tissue distribution are very similar to that of respective bird and mammalian enzymes.

Enhancement of therapeutic efficacy of bleomycin by incorporation into biodegradable poly-d,l-lactic acid.

A new system for the delivery bleomycin (BLM) to target lesions was established by incorporating BLM into a small cylinder of a biodegradable polylactic acid (PLA) of low molecular weight. Cross-sectional analysis of the system (BLM-PLA) showed that BLM particles were uniformly enclosed in the PLA matrix. In vitro studies demonstrated that BLM was released continuously for more than 3 weeks from BLM-PLA immersed in saline. BLM-PLA was implanted subcutaneously into the backs of rats. A high concentration of BLM was maintained in the connective tissues near the implants for 2 weeks. In contrast, the level of BLM activity was low when a BLM solution (BLM-SOL) was administered subcutaneously by injection. The concentration of BLM in the abdominal lymph nodes was significantly higher following BLM-PLA implantation than following subcutaneous BLM-SOL injection. The inhibitory effects of BLM-PLA and BLM-SOL on tumor growth were compared with no treatment using a subcutaneously transplanted Yoshida sarcoma. The antitumor effect of BLM-PLA was significantly higher than that of BLM-SOL and no treatment. BLM-PLA also resulted in a more favorable distribution of BLM than BLM-SOL. Thus, BLM-PLA proved to be effective in controlling this experimentally transplanted tumor.

Activity reduction of radioactive mixed wastes for subsequent carboxylate determinations

Tank wastes are usually very basic, pH>12, and extremely radioactive. An ion exchange method for removing most of the radioactive components has been developed. The sample can then be removed from the hot cell facility to be analyzed for chelator, chelator fragments, and low-molecular weight acids. The use of cation exchange resin in the sample preparation does not introduce or remove any organic carbon.

Bovine kidney low molecular weight acid phosphatase: FMN-dependent kinetics.

A low molecular weight bovine kidney acid phosphatase, electrophoretically homogeneous and with a relative molecular mass of 17.8 kDa, was used in this work. Among the various substrates tested, FMN was found to be the most effective, at pH 7.0. Distinct activation energy values were obtained for p-nitrophenyl phosphate- (45.44 kJ mol-1) and flavin mononucleotide- (28.60 kJ mol-1) hydrolysis reactions. The FMN hydrolysis was strongly inhibited by Cu2 and pCMB, but activated by guanosine. Pyridoxal-phosphate and vanadate were competitive inhibitors for the FMN-dependent reaction.

Characterization of the amsI gene product as a low molecular weight acid phosphatase controlling exopolysaccharide synthesis of Erwinia amylovora

The ams region, responsible for amylovoran synthesis of the fireblight pathogen Erwinia amylovora, contains the gene amsI encoding a 144 amino acid protein with homology to mammalian low molecular weight acid phosphatases [Bugert and Geider (1995) Mol. Microbiol. 15, 917–933]. A DNA fragment with amsI was cloned under the control of the lac promoter on a high copy number plasmid. The gene product of amsI is about 17 kDa in a protein expression system and had the enzymatic activity of an acid phosphatase. This is the first report about a low molecular weight acid phosphatase activity in prokaryotes. As part of the large ams transcript, expression of amsI was affected by the activator proteins RcsA and RcsB. Overexpression of amsI in E. amylovora caused a strong increase of acid phosphatase activity, but additionally a strong reduction in EPS synthesis, phenotypically similar to a mutation in the gene. The gene product may participate in changes of phosphorylation required for the biosynthesis of EPS such as recycling the lipid carrier diphosphate to the monophosphate form.

Separation of organic low molecular weight aluminium complexes in soil solution by liquid chromatography

A size exclusion chromatography method was developed for the separation of Al complexes of low molecular weight organic acids in soil solution. Bio-Gel P2 was used in a 1.6 x 30 cm column and the mobile phase consisted 0f 0.l M NaSCN of pH 4. The low molecular weight acids were determined by HPLC. The results show that 28–37% of the Al in the soil solution of the 0-horizon was bound t0 these acids. In the lower horizons Al coincided with the UV-trace at 400 run indicating organic complexes. Si was found in one major peak which was assumed to be a low molecular weight compound possibly silicic acid. As a compliment ultrafiltration was employed for characterisation

Fatty Acids of Cannabis Seeds

The chemical composition of the fatty acids in twenty four different samples of cannabis seeds was determined by gas liquid chromatography with flame ionization detector and coupled with a mass spectrometer. The identification of twenty fatty acids was based on comparison with authentic samples. In addition six other components were detected in some samples and shown to be oxygenated acids. The data showed that the seeds could be divided broadly into two groups, one with saturated and unsaturated fatty acids averaging 9.5±1.7% and 89.4±1.9% respectively, and the other with averages of 60.1±4.1% and 21.9±6.1% of the respective fatty acids. Examination of the effect of seed maturity on the fatty acid composition showed that the more mature the seeds are, the higher is the percentage of unsaturated fatty acids and the lower the percentage of saturated ones. Detection of oxygenated low molecular weight acids in the second group could be attributed to ageing. Comparison of the fatty acid composition of seeds of drug and fibre types showed no significant difference among mature seeds. In addition, there was no correlation between the fatty acid composition of the seeds and their geographical origin.

Phosphotyrosine protein phosphatases and diabetic pregnancy: an association between low molecular weight acid phosphatase and degree of glycemic control.

Low molecular weight acid phosphatase encoded by the highly polymorphic locus ACP1 is a member of the protein-tyrosin phosphatase family (PTPases) which plays an essential role in the control of receptor signalling through phosphotyrosine pathways. Recent experiments have shown that purified rat liver ACP, corresponding to human ACP1, is able to hydrolyze a phosphotyrosine-containing synthetic peptide corresponding to the 1146-1158 sequence of the human insulin receptor, and shows a high affinity for it. This prompted us to analyze the degree of glycemic control in relation to ACP1 genetic variability in a sample of 214 diabetic pregnant women including IDDM, NIDDM and gestational diabetes. The ACP1 genotype was also determined in 482 non-diabetic pregnant women. In diabetic women glycemic levels in the last trimester of pregnancy appear to be significantly associated with the ACP1 genotype, and correlate positively with ACP1 enzymatic activity. The data suggest that quantitative variations of ACP1 may influence the clinical manifestations of diabetic disorders, and call for further studies on the role of this enzyme in the modulation of insulin-receptor phosphotyrosine pathways.

Light-Induced Degradation of Aquatic Humic Substances by Simulated Sunlight

Abstract Filtered (0.22 μm) humic surface water and solutions of isolated fulvic and humic acids at pH 4 and 7 were treated with simulated sunlight. Silver nitrate was used as a bactericide in order to determine the extent of microbial degradation during exposure of the surface water sample. In most sets of samples the decrease in the dissolved organic carbon (DOC) content was found to be independent of the added silver. This reveals that the loss of carbon does not to any substantial extent result from growth of bacteria in the water. After prolonged irradiation part of the dissolved organic matter in the surface water sample was found to precipitate as iron complexes. Several aliphatic carboxylic acids of low molecular weight were quantified by gas chromatography/mass spectrometry after irradiation of the water samples for 48 h. These acids accounted for 10% of the remaining DOC in the surface water sample. The photo-induced degradation of the dissolved humic acid reference was slower than the corresponding degradation of the dissolved fulvic acid reference, and it was found to be further retarded at pH 4. Accordingly, the net concentration of the identified carboxylic acids was lowest in the humic acid solutions.

Phosphotyrosine-protein-phosphatases and human reproduction: an association between low molecular weight acid phosphatase (ACP1) and spontaneous abortion.

ACP1 (low molecular weight acid phosphatase) genetic polymorphism has been studied in 173 women with a history of two or more consecutive spontaneous abortions and in 1508 control subjects, including 482 normal pregnant women. The proportion of carriers of ACP1*C allele (*A/ *C, *B/*C) in women with a history of repeated spontaneous abortion is lower than in normal pregnant women and other control groups. Women with repeated spontaneous abortion show a specific decrease of ACP1 S isoform concentration as compared to normal pregnant women. The other component of ACP1 activity, the F isoform, does not show a significant difference between the two groups. The data suggest that women with ACP1 genotypes showing a high concentration of S isoform are relatively 'protected' against spontaneous abortion. Preliminary analysis of a sample of 352 normal puerperae along with their newborn babies supports this hypothesis.

Alterations of low molecular weight acid phosphatase protein level in Alzheimer's disease

We have previously reported that the activity of low molecular weight (LMW) acid phosphatase, which can remove tyrosine-linked phosphates of epidermal growth factor receptor, was significantly decreased in Alzheimer brains. In the present study, a specific antibody was prepared to analyze the protein level of this enzyme. Western blot analysis indicated that the level of LMW acid phosphatase protein was significantly reduced, whereas the activity of LMW acid phosphatase per enzyme molecule was not changed in Alzheimer brains. These results suggest that the reduction of LMW acid phosphate activity in Alzheimer brains is due to its decreased protein level in Alzheimer's disease.

Study of the bimolecular pyrolysis of acetic acid by the Austin Model 1 semi-empirical method

A bimolecular mechanism for the dehydration reactions involved in the pyrolysis of aliphatic acids of low molecular weight, e.g. acetic acid, was investigated theoretically by the semi-empirical AM1 (Austin Model 1) method. The AM1 results provide an acceptable description of the energy-related and structural aspects of the processes involved in the pyrolysis of acetic acid.

チロシン脱リン酸化作用を有する低分子量酸性ボスファターゼのアルツハイマー病における変動

Recent studies in Alzheimer brains have shown aberrant protein phosphorylation, suggesting an alteration in protein kinases and/or phosphoprotein phosphatases. The separation profile on Sephadex G-100 gel filtration chromatography revealed that two major forms of high-molecular-weight (HMW) and low-molecular-weight (LMW) acid phosphatase were present in the crude extracts of human brains. In Alzheimer brains, the LMW acid phosphatase activity was significantly decreased compared to that in control brains. A specific antibody was prepared to analyze the protein level of this enzyme. Western blot analysis indicated that the level of LMW acid phosphatase protein was significantly reduced, whereas the activity of LMW acid phosphatase per enzyme molecule was not changed in Alzheimer brains. These results suggest that the reduction of LMW acid phosphatase activity in Alzheimer brains is due to its decreased protein level in Alzheimer's disease. The endogenous substrate of LMW acid phosphatase in the brain was also investigated. LMW acid phosphatase was purified from bovine brain with a molecular mass of 17 kDa. The LMW acid phosphatase from bovine brain dephosphorylated a Mr. 170 kDa phosphotyrosine protein in rat brain extracts. This Mr. 170 kDa protein was considered to be the epidermal growth factor (EGF) receptor using a specific antibody. These results suggest that LMW acid phosphatase in the brain may regulate EGF receptor-dependent transmembrane signalling by dephosphorylating the phosphorylated receptor.