Growth Kinetics of Microbacterium lacticum and Nitrate-Dependent Degradation of Ethylbenzene under Anaerobic Conditions

A pure strain of Microbacterium lacticum DJ-1 capable of anaer-obic biodegradation of ethylbenzene was isolated from soil contaminated with gasoline. Growth of the strain and biodegradation of ethylbenzene in batch cultures led to stoichiometric reduction of nitrate. M. lacticum DJ-1 could degrade 100 mg L^?1 of ethylbenzene completely, with a maximum degradation rate of 15.02 ± 1.14 mg L^?1 day^?1. Increasing the initial concentration of ethy-lbenzene resulted in decreased degradative ability. The cell-specific growth rates on ethylbenzene conformed to the Haldane–Andrew model in the substrate level range of 10–150 mg L^?1. Kinetic parameters were determined by nonlinear regression on specific growth rates and various initial substrate concentrat-ions, and the values of the maximum specific growth rate, half saturation constant, and inhibition constant were 0.71 day^?1, 34.3 mg L^?1, and 183.5 mg L^?1, respectively. This is the first report of ethylbenzene biodegradation by a bacterium of Microbacterium lacticum under nitrate-reducing conditions.     

Stereo- and Regioselective Hydroxylation of α-Ionone by Streptomyces Strains

A total of 215 Streptomyces strains were screened for their capacity to regio- and stereoselectively hydroxylate β- and/or α-ionone to the respective 3-hydroxy derivatives. With β-ionone as the substrate, 15 strains showed little conversion to 4-hydroxy- and none showed conversion to the 3-hydroxy product as desired. Among these 15 Streptomyces strains, S. fradiae Tü 27, S. arenae Tü 495, S. griseus ATCC 13273, S. violaceoniger Tü 38, and S. antibioticus Tü 4 and Tü 46 converted α-ionone to 3-hydroxy-α-ionone with significantly higher hydroxylation activity compared to that of β-ionone. Hydroxylation of racemic α-ionone [(6R)-(−)/(6S)-(+)] resulted in the exclusive formation of only the two enantiomers (3R,6R)- and (3S,6S)-hydroxy-α-ionone. Thus, the enzymatic hydroxylation of α-ionone by the Streptomyces strains tested proceeds with both high regio- and stereoselectivity.Ionones and their derivatives are important intermediates in the metabolism of terpenoids, e.g., in carotenoid biosynthesis, and have been isolated from many sources (1a, 11). Compounds with a trimethylcyclohexane building block constitute essential aroma elements in many plant oils and thus have attracted the attention of the flavor and fragrance industry (3). Further, ionone derivatives, e.g., 3-hydroxy-β-ionone, could prove valuable intermediates for the chemoenzymatic synthesis of carotenoids, e.g., for astaxanthin and zeaxanthin (5).Microbial transformation of α- and/or β-ionone to a number of hydroxy and oxo derivatives has been reported for several fungal strains (2, 4, 8, 9, 18), mainly of the genus Aspergillus, but not for bacterial strains. 3-Hydroxy-α-ionone was observed, among other metabolites, when Cunninghamella blakesleeana ATCC 8688 (2) or Aspergillus niger JTS 191 (18) was used.Many species of the order Actinomycetes are known to catalyze a broad spectrum of xenobiotic transformations. Several cytochrome P-450-dependent monooxygenases from Streptomyces strains, which catalyze the hydroxylation of a wide range of substrates, have been investigated on the molecular level (12) and thus provide an interesting potential as biocatalysts for specific hydroxylation reactions by recombinant techniques.As a first step in this direction, we now report the screening of 215 Streptomyces strains for their capacity to hydroxylate β- and/or α-ionone to the respective 3-hydroxy derivatives in a regio- and stereoselective manner. The structure and stereochemistry of the main biotransformation product were characterized unequivocally by nuclear magnetic resonance (NMR) spectroscopy.     

Isolation of Human α-Fetoprote in Two Fractionation Steps and Demonstration of Homogeneity

Human α-fetoprotein (hAFP) has been isolated from cord serum in 40% yield using an isolation procedure consisting of only two major steps: affinity chromatography followed by preparative polyacrylamide gel electrophoresis (PAGE). The final product appeared homogeneous on the basis of five independent criteria for purity. Sodium dodecyl sulfate gel electrophoresis (SDS-PAGE) demonstrated a single polypeptide chain with molecular weight of 71,000. The protein exhibited an apparent isoelectric point (pÍ) of 4.85, molecular radius of 3.0 nm and a valence (net H⁺/molecule) of 21.9 derived from computation of analytical PAGE data. The two-step isolation procedure made it possible for a single operator to isolate milligram amounts of hAFP in a matter of weeks.     

Degradation of Cinnamate via β-Oxidation to Benzoate by a Defined,Syntrophic Consortium of Anaerobic Bacteria

A syntrophic consortium was enriched in a basal medium containing cinnamate as the carbon and energy source. It was found to consist of three morphologically distinct microbes, viz., a short, rod-shaped, non-motile bacterium with distinctly pointed ends, Papillibacter cinnamivorans; a rod-shaped, motile bacterium with rounded ends, Syntrophus sp.; and a methanoarchaeon, Methanobacterium sp. This methanogen was then replaced by a collection strain of Methanobacterium formicicum. A syntrophic interdependency of the three partners of the consortium was observed during growth on cinnamate. In the presence of bromoethanesulfonic acid (BESA), cinnamate was transformed to benzoate, whereas under methanogenic conditions without BESA, cinnamate was first transformed to benzoate via β-oxidation and subsequently completely degraded into acetate, CH₄, and CO₂. Papillibacter cinnamivorans was responsible for benzoate production from cinnamate, whereas a syntrophic association between Syntrophus sp. and the methanogen degraded benzoate to acetate, CH₄, and CO₂. A new anaerobic degradation pathway of cinnamate into benzoate via β-oxidation by a pure culture of P. cinnamivorans is proposed. Received: 27 December 2001 / Accepted: 28 March 2002     

Hydroxylation and Further Oxidation of Δ9-Tetrahydrocannabinol by Alkane-Degrading Bacteria

The microbial biotransformation of Δ⁹-tetrahydrocannabinol was investigated using a collection of 206 alkane-degrading strains. Fifteen percent of these strains, mainly gram-positive strains from the genera Rhodococcus, Mycobacterium, Gordonia, and Dietzia, yielded more-polar derivatives. Eight derivatives were produced on a mg scale, isolated, and purified, and their chemical structures were elucidated with the use of liquid chromatography-mass spectrometry, ¹H-nuclear magnetic resonance (¹H-NMR), and two-dimensional NMR (¹H-¹H correlation spectroscopy and heteronuclear multiple bond coherence). All eight biotransformation products possessed modified alkyl chains, with hydroxy, carboxy, and ester functionalities. In a number of strains, β-oxidation of the initially formed C₅ carboxylic acid led to the formation of a carboxylic acid lacking two methylene groups.Δ⁹-Tetrahydrocannabinol (Δ⁹-THC) is the decarboxylated product of the corresponding Δ⁹-THC acid, the major cannabinoid present in the cannabis plant (Cannabis sativa L., Cannabaceae). This compound is officially registered as a drug for the stimulation of appetite and antiemesis in patients under chemotherapy and human immunodeficiency virus therapy regimens. Other biological activities ascribed to this compound include lowering intraocular pressure in glaucoma, acting as an analgesic for muscle relaxation, immunosuppression, sedation, bronchodilation, and neuroprotection (11).Δ⁹-THC and many of its derivatives are highly lipophilic and poorly water soluble. Calculations of the n-octanol/water partition coefficient (K_o/w) of Δ⁹-THC at neutral pH vary between 6,000, using the shake flask method (15), and 9.44 × 10⁶, by reverse-phase high-performance liquid chromatography estimation (19). The poor water solubility and high lipophilicity of cannabinoids cause their absorption across the lipid bilayer membranes and fast elimination from blood circulation. In terms of the “Lipinsky rule of 5” (14), the high lipophilicity of cannabinoids hinders the further development of these compounds into large-scale pharmaceutical products.To generate more water-soluble analogues, one can either apply de novo chemical synthesis (as, e.g., in reference 16) or modify naturally occurring cannabinoids, e.g., by introducing hydroxy, carbonyl, or carboxy groups. Chemical hydroxylation of compounds such as cannabinoids is difficult (Δ⁹-THC is easily converted into Δ⁸-THC under mild conditions), and therefore microbial biotransformation of cannabinoids is potentially a more fruitful option to achieve this goal.So far, studies on biotransformation of Δ⁹-THC were mainly focused on fungi, which led to the formation of a number of mono- and dihydroxylated derivatives. Previous reports on the biotransformation of cannabinoids by various microorganisms are summarized in Table ​Table1.1. The aim of the present study was to test whether bacterial strains are capable of transforming Δ⁹-THC into new products (with potentially better pharmaceutical characteristics) at a higher yield and specificity than previously found for fungal strains. For this purpose, we have chosen to use a collection of alkane-degrading strains, since it was shown in previous studies (8, 18, 20) that alkane oxygenases often display a broad substrate range. Production of novel cannabinoid derivatives that might have interesting pharmacological activities was another objective of this project.

TABLE 1.

Previous biotransformation experiments conducted using various microorganisms to transform cannabinoids

Distinct Actions by Paenibacillus sp. Strain E18 α-l-Arabinofuranosidases and Xylanase in Xylan Degradation

We cloned a Paenibacillus sp. strain E18 5.3-kb xylanolytic gene cluster that contains three open reading frames encoding two family 43 α-l-arabinofuranosidases (Abf43A and Abf43B) and one family 10 xylanase (XynBE18). The deduced amino acid sequences of Abf43A and Abf43B were at most 68% and 63% identical to those of two putative family 43 proteins from Clostridium sp. strain DL-VIII ({"type":"entrez-protein","attrs":{"text":"EHI98634.1","term_id":"357170460","term_text":"EHI98634.1"}}EHI98634.1 and {"type":"entrez-protein","attrs":{"text":"EHI98635.1","term_id":"357170461","term_text":"EHI98635.1"}}EHI98635.1), respectively, but were only 11% identical to each other. Recombinant Abf43A and Abf43B had similar activities at 45°C and pH 6.0 but varied in thermostabilities and substrate specificities. Abf43B was active against only 4-nitrophenyl α-l-arabinofuranoside, whereas Abf43A acted on 4-nitrophenyl α-l-arabinofuranoside, wheat arabinoxylan, 4-nitrophenyl α-d-xylopyranoside, and sugar beet arabinan. The sequential and combined effects on xylan degradation by XynBE18, Abf43A, and Abf43B were characterized. For beechwood, birchwood, and oat spelt xylans as the substrates, synergistic effects were found when XynBE18 and Abf43A or Abf43B were incubated together and when the substrates were first incubated with Abf43A or Abf43B and then with XynBE18. Further high-performance liquid chromatography (HPLC) analysis showed that the amounts of xylobiose and xylose increased sharply in the aforementioned reactions. For water-soluble wheat arabinoxylan as the substrate, Abf43A not only released arabinose but also had a synergistic effect with XynBE18. Synergy may arise as the result of removal of arabinose residues from xylans by α-l-arabinofuranosidases, which eliminates steric hindrance caused by the arabinose side chains and which allows xylanases to then degrade the xylan backbone, producing short xylooligosaccharides.     

Hydroxylation and glycosylation of Δ9-tetrahydrocannabinol by Catharanthus roseus cell suspension culture

Δ⁹-tetrahydrocannabinol is the active constituent in Cannabis sativa, with reported analgesic, anti-emetic, anti-oxidative, neuroprotective, and anti-inflammatory activities. Δ⁹-THC has been used to treat a number of disease states including pain, anxiety, asthma, glaucoma, and hypertension. Poor water solubility of Δ⁹-THC greatly reduces its clinical effectiveness. Consequently, there is a need to modify the compound to increase its polarity and pharmaceutical efficacy. The aim of this study was to test the capability of Catharanthus roseus suspension cultured cells to convert Δ⁹-THC into more polar derivatives. The transformed metabolites were analyzed and isolated by HPLC. Structures of some new derivatives were proposed on the basis of molecular ion peaks and fragmentation patterns obtained from LC-MS and UV spectra obtained by HPLC, respectively. Δ⁹-THC was rapidly absorbed by Catharanthus roseus cultured cells and upon biotransformation new glycosylated and hydroxylated derivatives were isolated by preparative HPLC. In addition, cannabinol was detected as degradation product, including its glycosylated derivative. Based on these results, it is concluded that Catharanthus cultured cells have great potential to transform Δ⁹-THC into more polar derivatives and can be used for the large scale production of new cannabinoids, which can be a source of new compounds with interesting pharmacological profiles.     

Anaerobic Metabolism of Catechol by the Denitrifying Bacterium Thauera aromatica—a Result of Promiscuous Enzymes and Regulators?

The anaerobic metabolism of catechol (1,2-dihydroxybenzene) was studied in the betaproteobacterium Thauera aromatica that was grown with CO₂ as a cosubstrate and nitrate as an electron acceptor. Based on different lines of evidence and on our knowledge of enzymes and genes involved in the anaerobic metabolism of other aromatic substrates, the following pathway is proposed. Catechol is converted to catechylphosphate by phenylphosphate synthase, which is followed by carboxylation by phenylphosphate carboxylase at the para position to the phosphorylated phenolic hydroxyl group. The product, protocatechuate (3,4-dihydroxybenzoate), is converted to its coenzyme A (CoA) thioester by 3-hydroxybenzoate-CoA ligase. Protocatechuyl-CoA is reductively dehydroxylated to 3-hydroxybenzoyl-CoA, possibly by 4-hydroxybenzoyl-CoA reductase. 3-Hydroxybenzoyl-CoA is further metabolized by reduction of the aromatic ring catalyzed by an ATP-driven benzoyl-CoA reductase. Hence, the promiscuity of several enzymes and regulatory proteins may be sufficient to create the catechol pathway that is made up of elements of phenol, 3-hydroxybenzoate, 4-hydroxybenzoate, and benzoate metabolism.     

Conversion of (−)-Carvone and (+)-Carvone by a Strain of Aspergillus niger

The conversion of (?)-carvone and (+)-carvone by a strain of Aspergillus niger was studied as one of the series of biochemical reduction of terpenes.

(?)-Carvone was found to be reduced essentially to (+)-neodihydrocarveol, although (+)-dihydrocarvone and (+)-isodihydrocarvone were also formed in small amounts, whereas (+)-carvone was converted to (?)-isodihydrocarvone, (?)-isodihydrocarveol, (?)-neoisodihydrocarveol, (?)-dihydrocarvone, (?)-neodihydrocarveol, and (+)-dihydrocarveol, of which the former three were the major products.

The metabolic pathways for (?)-carvone and (+)-carvone by the strain of Aspergillus niger are discussed and the results on microbial and chemical reductions of carvone and dihydrocarvone are summarized.     

Degradation of wheat straw by a microbial community —stimulation by a polysaccharidase complex

Laboratory-scale reactors were used to watch aspects of biodegradation of wheat straw when supplemented with polysaccharidases (Czym) to increase the enzyme production of microorganisms involved during a composting process for mushroom production. Biochemical and biological parameters were tested both under aerobic and O₂-limited conditions to assess degradability. These were measurement of released CO₂ and NH₃, determination of neutral detergent fibre content and cellulase activities from compost extract. The addition of Czym to decomposing straw had three consequences: (i) it supplied and released low quantities of readily available sugars; (ii) it increased the cellulase activities in the substrates; (iii) it increased the number of bacteria under aerobic conditions. The three effects were linked and the small quantity of sugars released by the addition of Czym may have acted as an activator of bacterial activities through an inductive mechanism. Correspondence to: S. Libmond     

Effects of Two Carbamates on Infective Juveniles of Stemernema carpocapsae All Strain and Steinernema feltiae Ume? Strain

Laboratory bioassays were conducted to determine the effects of two carbamates, carbofuran (an acetylcholinesterase inhibitor) and fenoxycarb (a juvenile hormone analog), on survival and infectivity of the infective juveniles (IJ) of Steinernema feltiae Umeå strain and Steinernema carpocapsae All strain. Both insecticides caused mortality of IJ in a dose-related fashion. The two nematode species were equally sensitive to fenoxycarb (LD₅₀ ca. 0.03mg/ml). Whereas IJ of S. feltiae were several orders of magnitude more sensitive to carbofuran (LD₅₀ ≤ 0.2 μg/ml) than to fenoxycarb, S. carpocapsae IJ displayed approximately the same degree of sensitivity to carbofuran (LD₅₀ 0.01-0.03 mg/ml) as they did toward fenoxycarb. Toxicity of the carbamates was the same at all exposure periods from 24 to 168 hours'' duration. Determinations of infective doses of nematodes required to cause 50% mortality of Galleria mellonella larvae showed that the infectivity of IJ that survived exposure to either of the two carbamates was not compromised by treatment.     

Viability of Plant–Pathogenic Fungi Reduced by Anaerobic Digestion

Feedstock of anaerobic digestion infected with phytopathogens could enhance the risk of spreading those pathogens to uninfested field through digestate. The viability of Fusarium proliferatum, Fusarium verticillioides, Sclerotinia sclerotiorum, and Rhizoctonia solani was investigated in anaerobic digestion experiments using infected plant material of sorghum (Sorghum bicolor), sugar beet (Beta vulgaris subsp. vulgaris var. altissima), and potato (Solanum tuberosum L.). Results from lab-scale reactors were confirmed in full-scale biogas plants. Anaerobic digestion under mesophilic conditions (35–42 °C) reduced most of the phytopathogens of feedstocks investigated. Thus, S. sclerotiorum and R. solani lost their viability within 6 h. In the case of sorghum, however, Fusarium spp. infected feedstock required a maximum of 138 h for sanitation. Thus, the risk of spreading plant pathogens with the digestate can only be decreased when the feedstock would undergo an additional treatment before anaerobic digestion or of the resulting digestate.     

Degradation of Phospholipids and Liquefaction of Pressed Baker’s Yeast by Acetic Acid Vapour

When pressed baker’s yeast (Saccharomyces cerevisiae) was exposed to the vapour of acetic acid, autolysis of yeast cells was induced in 3 or 4 hr. In order to elucidate the mechanism of the autolysis caused by the AcOH-treatment, we investigated variations in the lipid content of yeast cells during the treatment. The degradation of phospholipids and the accumulation of free fatty acids occurred within 3 hr. Formic acid exerted a similar effect on the pressed yeast. The effect of propionic acid was not seen in 3hr but was after 18 hr. When the homogenate of fresh yeast cells was incubated in the acidic region below pH 4.5 for 1 hr, phospholipids were hydrolyzed and free fatty acids were accumulated. Such deacylation of phospholipids was observed even at pH 6 on incubation for 12hr, but not observed at pH 7 or above pH 9. At pH 8, although phospholipids were somewhat degraded, free fatty acids almost never accumulated but diacylglycerol did accumulate.

Therefore, yeast cells have inherently phospholipid-acylhydrolases and, on AcOH-treatment, such enzymes may degrade membrane phospholipids to induce the autolysis of pressed yeast.     

β-TrCP-Mediated Ubiquitination and Degradation of PHLPP1 Are Negatively Regulated by Akt

PHLPP1 belongs to a novel family of Ser/Thr protein phosphatases that serve as tumor suppressors by negatively regulating Akt signaling. Our recent studies have demonstrated that loss of PHLPP expression occurs at high frequency in colorectal cancer. In this study, we identified PHLPP1 as a proteolytic target of a β-TrCP-containing Skp-Cullin 1-F-box protein (SCF) complex (SCF^β-TrCP) E3 ubiquitin ligase in a phosphorylation-dependent manner. Overexpression of wild-type but not ΔF-box mutant β-TrCP leads to decreased expression and increased ubiquitination of PHLPP1, whereas knockdown of endogenous β-TrCP has the opposite effect. In addition, we show that the β-TrCP-mediated degradation requires phosphorylation of PHLPP1 by casein kinase I and glycogen synthase kinase 3β (GSK-3β), and activation of the phosphatidylinositol 3-kinase/Akt pathway suppresses the degradation of PHLPP1 by inhibiting the GSK-3β activity. Furthermore, expression of a degradation-deficient PHLPP1 mutant in colon cancer cells results in a more effective dephosphorylation of Akt and inhibition of cell growth. Taken together, our findings demonstrate a key role for β-TrCP in controlling the level of PHLPP1, and activation of Akt negatively regulates this degradation process.Hyperactivation of phosphatidylinositol 3-kinase/Akt signaling is commonly associated with human cancers (1, 5, 27). Inability to terminate the growth and survival signals mediated by Akt is one of the major mechanisms contributing to the development of cancer (1, 22, 32). The activation of Akt involves two phosphorylation steps: it is first phosphorylated at the activation loop (Thr308) within the kinase core by PDK-1 and subsequently at the hydrophobic motif (Ser473) in the C terminus by the TORC2 complex (22). Since the activity of Akt is tightly controlled by phosphorylation, dephosphorylation of Akt leads to effective signaling termination by inactivating the kinase. Recently, a novel family of Ser/Thr protein phosphatases, PHLPP, has been identified to fulfill the role of a negative regulator for Akt via direct dephosphorylation (3, 14). Two isoforms of PHLPP, namely PHLPP1 and PHLPP2, are found in this phosphatase family. Although the two isoforms of PHLPP share their ability to dephosphorylate Akt, each PHLPP preferentially regulates a subset of Akt isoforms in human lung cancer cells (3). Several lines of evidence suggest that PHLPP functions as a tumor suppressor. For example, overexpression of PHLPP in glioblastoma and colon cancer cells inhibits tumorigenesis in xenografted nude mice (14, 20), while decreased PHLPP expression correlates with increased metastastic potential in breast cancer cells (26). Furthermore, our recent studies have shown that downregulation of both PHLPP isoforms occurs at high frequency in colorectal cancer clinical samples (20). Loss of tumor suppressor expression can be caused by alterations at the gene level such as loss of heterozygosity or gene methylation. However, dysregulation of protein degradation pathways has also been implicated as a reason for downregulation of tumor suppressors (2, 6, 16).The ubiquitin (Ub) proteasome pathway controls degradation of the majority of eukaryotic proteins (12). β-TrCP belongs to a large family of F-box-containing proteins, and it serves as the substrate recognition subunit in the SCF (Skp1-Cullin 1-F-box protein) Ub-E3 ligase protein complex (4). By regulating the proteolytic process of its substrates, β-TrCP plays an important role in controlling cell cycle and cancer biogenesis (10). It is believed that β-TrCP-mediated ubiquitination requires phosphorylation of its substrates (35). A consensus binding motif with the sequence of DSG(X)_2-nS (so-called “phospho-degron”) has been proposed, in which the two serine residues are phosphorylated prior to binding to β-TrCP (4). However, variations of this motif, including replacement of the serine residues with phosphomimetic residues (e.g., Glu or Asp) in the substrate sequence, have been shown to be equally effective in mediating association with β-TrCP (31, 34).In this study, we report the identification of PHLPP1 as a proteolytic target of β-TrCP. We show that the degradation process of PHLPP1 depends on casein kinase I (CK1)- and glycogen synthase kinase 3 (GSK-3)-mediated phosphorylation, and activation of Akt negatively regulates PHLPP1 turnover. In addition, a PHLPP1 phosphorylation/degradation mutant antagonizes Akt more effectively in colon cancer cells.     

Degradation of oil sludge by landfarming — a case-study at the Ghent harbour

Large-scale landfarming experiments have been performed on a loamy sand soil. An amount of 1,350 m³/ha oil sludge together with nutrients (N,P,K) and a bacterial inoculum were applied at two different times over a five-year period. At both test periods, biodegradation of the hydrocarbons (HC) was best fitted with first order reaction kinetics with degradation rates ranging from about 4 g HC/kg dry soil per year to about 15 g HC/kg dry soil per year. Toxicity tests on the aqueous soil extracts as well as plant growth and worm tests on the landfarm soil showed no striking negative effects of residual hydrocarbons. Migration of oil, nitrate and phosphate to the groundwater was minimal. In view of the diversity of solvents recommended in the literature, twenty extractants were tested for their capacity to remove HC from the loamy sand soil. Chlorinated solvents, such as dichloromethane and chloroform, were the most effective. Yet, in view of its effectiveness and low toxicity, acetone appears a suitable solvent for the extraction of soils and sediments polluted with hydrocarbons. This case-study revealed that oil sludge can effectively be treated by landfarming, if appropriate technical measures are taken and a sufficient time (minimum 15 years) for bioremediation is provided.     

Phosphorylation of LSD1 by PKCα Is Crucial for Circadian Rhythmicity and Phase Resetting

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Degradation of β-Conglycinin β-Homotrimer by Papain: Independent Occurrence of Limited and Extensive Proteolysis

Limited and extensive proteolysis occur when β-conglycinin β homo-trimer (β₃-conglycinin) from soybeans is attacked by papain. Slow limited proteolysis is restricted to cleavage of β₃-conglycinin polypeptides into subunit halves (N- and C-terminal domains) that are further slightly truncated. The kinetics of limited and extensive proteolyses analyzed separately indicates that the two processes occur independently from the very beginning of the reaction. In contrast, limited proteolysis of phaseolin from common beans has been found to be prerequisite for the onset of its extensive proteolysis. The dramatic distinction between the degradation patterns of β₃-conglycinin and phaseolin, homologous storage 7S globulins, suggests the existence of intrinsic differences in their structures. This hypothesis is supported by comparative analysis of the accessibilities to the solvent of amino acid residues in phaseolin and β₃-conglycinin structures, which indicated the relatively low packing density of the latter, resulting in enhanced susceptibility of it to extensive proteolysis.     

Anaerobic microbial dehalogenation of organohalides — state of the art and remediation strategies

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