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Substrate specificity and other properties of the inducible S3 secondary alkylsulphohydrolase purified from the detergent-degrading bacterium Pseudomonas C12B.

ABSTRACT: The inducible S3 secondary alkylsulphohydrolase of the soil bacterium Pseudomonas C12B was purified to homogeneity (683-fold from cell-free extracts by a combination of column chromatography on DEAE-cellulose. Sephadex G-100 and Blue Sepharose CL-6B. The enzyme has a molecular weight in the region of 40000--46000, and is active over a broad range of pH from 5 to 9, with maximum activity at pH 8.2. The preferred substrates of the enzyme are the symmetrical secondary alkylsulphate esters such as heptan-4-yl sulphate and nonan-5-yl sulphate and the asymmetric secondary octyl and nonyl sulphate esters with the sulphate group attached to C-3 or C-4. However, for each asymmetric ester, the L-isomer is much more readily hydrolysed than the D-isomer. This specificity is interpreted in terms of a three-point attachment of the substrate to the enzyme's active site. The alkyl chains on either side of the esterified carbon atom are bound in two separate sites, one of which can only accommodate alkyl chains of limited size. The third site binds the sulphate group. Enzymic hydrolysis of this group is accompanied by complete inversion of configuration at the asymmetric carbon atom. The implied cleavage of the C--O bond of the C--O--S ester linkage was confirmed by 18O-incorporation studies.

SUBMITTER: Shaw DJ

PROVIDER: S-EPMC1162506 | biostudies-other | 1980 Apr

REPOSITORIES: biostudies-other

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Purification and properties of the P2 primary alkylsulphohydrolase of the detergent-degrading bacterium pseudomonas C12B.

Project description:The P2 primary alkylsulphohydrolase of the soil bacterium Pseudomonas C12B was purified to homogeneity (200-250-fold) by column chromatography on DEAE-cellulose, Sephadex G-100 and butyl-agarose. The intact protein is a dimer with a mol. wt. of 160 000. Activity towards primary alkyl sulphate esters was maximal at pH 8.3, varied little in the range pH 7.8-8.7, but decreased sharply at higher pH. For a homologous series of primary alkyl sulphate substrates (C6-C12), logKm decreased linearly with increasing chain length, corresponding to a contribution to the free energy of association between enzyme and substrate of -2.5kJ/mol for each additional CH2 group in the alkyl chain. logKi for the competitive inhibition by secondary alkyl 2-sulphate esters followed a similar pattern (-2.4kJ/mol for each additional CH2 group) except that only n-1 carbon atoms effectively participate in hydrophobic bonding, implying that the C-1 methyl group is not involved. logKi values for inhibition primary alkanesulphonates also depended linearly on chain length but with a diminished gradient, indicating a free-energy increment of -1.2kJ/mol per additional CH2 group. The collective results showed the presence of a hydrophobic site on the enzyme capable of accomodating an alkyl chain of considerable length. Cationic structures (in the form of arginine, lysine or histidine), whose presence might be expected for binding the anionic sulphate group, were not detectable at the active site.

| S-EPMC1161265 | biostudies-other

Purification and properties of the S1 secondary alkylsulphohydrolase of the detergent-degrading micro-organism, Pseudomonas C12B.

Project description:The S1 secondary alkylsulphohydrolase of the detergent-degrading micro-organism, Pseudomonas C12B, was separated from other alkylsulphohydrolases and purified to homogeneity. Under the experimental conditions used the enzyme completely hydrolysed d-octan-2-yl sulphate (d-1-methylheptyl sulphate), but showed no activity towards the corresponding l-isomer. Additional evidence has been obtained to indicate that it is probably optically stereospecific for d-secondary alkyl sulphate esters with the ester sulphate group at C-2 and with a chain length of at least seven carbon atoms. Enzyme activity towards racemic samples of heptan-2-yl sulphate (1-methylhexyl sulphate), octan-2-yl sulphate and decan-2-yl sulphate (1-methylnonyl sulphate) increased with increasing chain length. l-Octan-2-yl sulphate is a competitive inhibitor of the enzyme, as are certain primary alkyl sulphates and primary alkanesulphonates. Inhibition by each of the last two types of compounds is characteristic of the behaviour of an homologous series. Inhibition increases with increasing chain length and plots of log K(i) values against the number of carbon atoms in each alkyl chain show the expected linear relationship. A crude preparation of the S2 secondary alkylsulphohydrolase was used to show that this particular enzyme hydrolyses l-octan-2-yl sulphate, but is probably inactive towards the corresponding d-isomer. The similarity of the S1 and S2 enzymes to the CS2 and CS1 enzymes respectively of Comamonas terrigena was established, and some comments have been made on the possible roles of these and other alkylsulphohydrolases in the biodegradation of detergents.

| S-EPMC1183839 | biostudies-other

Specificity of P2 primary alkylsulphohydrolase induction in the detergent-degrading bacterium Pseudomonas C12B. Effects of alkanesulphonates, alkyl sulphates and other related compounds.

Project description:Primary alkanesulphonates were shown to serve as non-metabolizable (gratuitous) inducers of the P2 primary alkylsulphohydrolase enzyme in resting cell suspensions of Pseudomonas C12B. The effects of increasing concentrations of inducer on the production of enzyme were complex and suggestive of a multiphasic phenomenon. However, it was possible to determine Kinducer constants (analogous to Km or Ki) for alkanesulphonates of chain length from C7 to c12. these decreased with increasing chain length in a manner characteristic of an homologous series. Primary alkyl sulphates also served as good inducers of alkylsulphohydrolase, but valid kinetic values could not be obtained because these esters are good substrates for the enzyme and are therefore appreciably hydrolysed during the induction period. Small amounts of enzyme were also produced when cyprinol sulphate, dodecyltriethoxy sulphate C12H23-[O-CH2-CH2]3-O-SO3-Na+), Crag herbicide and some secondary alkyl sulphates were tested as inducers.

| S-EPMC1161264 | biostudies-other

Primary alkylsulphatase activities of the detergent-degrading bacterium Pseudomonas C12B. Purification and properties of the P1 enzyme.

Project description:The P1 primary alkylsulphatase of Pseudomonas C12B was purified 1500-fold to homogeneity by a combination of streptomycin sulphate precipitation of nucleic acids, (NH4)2SO4 fractionation and chromatography on columns of DEAE-cellulose, Sephacryl S-300 and butyl-agarose. The protein was tetrameric with an Mr of 181000-193000, and exhibited maximum activity at pH 6.1. Primary alkyl sulphates of carbon-chain length C1-C5 or above C14 were not substrates, but the intermediate homologues were shown to be substrates, either by direct assay (C6-C9 and C12) or by gel zymography (C10, C11, C13 and C14). Increasing the chain length from C6 to C12 led to diminishing Km. Values of delta G0' for binding substrates to enzyme were dependent linearly on chain length, indicating high dependence on hydrophobic interactions. Vmax./Km values increased with increasing chain length. Inhibition by alk-2-yl sulphates and alkane-sulphonates was competitive and showed a similar dependence on hydrophobic binding. The P1 enzyme was active towards several aryl sulphates, including o-, m- and p-chlorophenyl sulphates, 2,4-dichlorophenyl sulphate, o-, m- and p-methoxyphenyl sulphates, m- and p-hydroxyphenyl sulphates and p-nitrophenyl sulphate, but excluding bis-(p-nitrophenyl) sulphate and the O-sulphate esters of tyrosine, nitrocatechol and phenol. The arylsulphatase activity was weak compared with alkylsulphatase activity, and it was distinguishable from the de-repressible arylsulphatase activity of Pseudomonas C12B reported previously. Comparison of the P1 enzyme with the inducible P2 alkylsulphatase of this organism, and with the Crag herbicide sulphatase of Pseudomonas putida, showed that, although there are certain similarities between any two of the three enzymes, very few properties are common to all three.

| S-EPMC1146854 | biostudies-other

The mechanism of action of primary alkylsulphohydrolase and arylsulphohydrolase from a detergent-degrading micro-organism.

Project description:Previous studies have shown that secondary alkylsulphohydrolases from certain detergent-degrading micro-organisms are unusual esterases in that they catalyse fission of the C-O bond of the alkyl sulphate ester linkage. The position of bond fission catalysed by a primary alkylsulphatase and an arylsulphohydrolase present in Pseudomonas C12B has now been investigated. The primary alkylsulphatase behaved like the secondary alkylsulphohydrolases in cleaving the C-O bond of potassium heptan-1-yl sulphate. In contrast, the arylsulphohydrolase, in common with other similar enzymes previously studied, catalysed the fission of the O-S bond of potassium p-nitrophenyl sulphate.

| S-EPMC1183735 | biostudies-other

A Broad Temperature Active Lipase Purified From a Psychrotrophic Bacterium of Sikkim Himalaya With Potential Application in Detergent Formulation.

Project description:Bacterial lipases with activity spanning over a broad temperature and substrate range have several industrial applications. An efficient enzyme-producing bacterium Chryseobacterium polytrichastri ERMR1:04, previously reported from Sikkim Himalaya, was explored for purification and characterization of cold-adapted lipase. Optimum lipase production was observed in 1% (v/v) rice bran oil, pH 7 at 20°C. Size exclusion and hydrophobic interaction chromatography purified the enzyme up to 21.3-fold predicting it to be a hexameric protein of 250 kDa, with 39.8 kDa monomeric unit. MALDI-TOF-MS analysis of the purified lipase showed maximum similarity with alpha/beta hydrolase (lipase superfamily). Biochemical characterization of the purified enzyme revealed optimum pH (8.0), temperature (37°C) and activity over a temperature range of 5-65°C. The tested metals (except Cu2+ and Fe2+) enhanced the enzyme activity and it was tolerant to 5% (v/v) methanol and isopropanol. The Km and Vmax values were determined as 0.104 mM and 3.58 U/mg, respectively for p-nitrophenyl palmitate. Bioinformatics analysis also supported in vitro findings by predicting enzyme's broad temperature and substrate specificity. The compatibility of the purified lipase with regular commercial detergents, coupled with its versatile temperature and substrate range, renders the given enzyme a promising biocatalyst for potential detergent formulations.

| S-EPMC7329984 | biostudies-literature

Substrate specificity and reaction mechanism of purified alkane hydroxylase from the hydrocarbonoclastic bacterium Alcanivorax borkumensis (AbAlkB).

Project description:An alkane hydroxylase from the marine organism Alcanivorax borkumensis (AbAlkB) was purified. The purified protein retained high activity in an assay with purified rubredoxin (AlkG), purified maize ferredoxin reductase, NADPH, and selected substrates. The reaction mechanism of the purified protein was probed using the radical clock substrates bicyclo[4.1.0]heptane (norcarane), bicyclo[3.1.0]hexane (bicyclohexane), methylphenylcyclopropane and deuterated and non-deuterated cyclohexane. The distribution of products from the radical clock substrates supports the hypothesis that purified AbAlkB hydroxylates substrates by forming a substrate radical. Experiments with deuterated cyclohexane indicate that the rate-determining step has a significant CH bond breaking character. The products formed from a number of differently shaped and sized substrates were characterized to determine the active site constraints of this AlkB. AbAlkB can catalyze the hydroxylation of a large number of aromatic compounds and linear and cyclic alkanes. It does not catalyze the hydroxylation of alkanes with a chain length longer than 15 carbons, nor does it hydroxylate sterically hindered C-H bonds.

| S-EPMC3595352 | biostudies-literature

Further studies on the substrate specificity and inhibition of the stereospecific CS2 secondary alkylsulphohydrolase of Comamonas terrigena.

Project description:A series of d-alkan-2-yl sulphate esters (C(7)-C(14)) were prepared by sulphation of the resolved parent alcohols by a method that entails complete retention of configuration. These sulphate esters were tested as substrates for the stereospecific CS2 secondary alkylsulphohydrolase of Comamonas terrigena. V(max.) reached a maximum with the C(9) compound, whereas logK(m) decreased linearly as the alkyl-chain length was increased from C(7) to C(14). A parallel series of l-alkan-2-yl sulphates was also prepared, and these esters, together with homologous series of primary alkyl sulphates and primary alkanesulphonates, were shown to be competitive inhibitors of the CS2 enzyme. For each series of compounds, logK(i) values decreased linearly with increasing alkyl-chain length. Plots of chain length against the standard free energy of binding (DeltaG(0)) of substrate and inhibitors to the CS2 enzyme showed that the standard free energy of association of a -CH(2)- group with the enzyme was 2.0-2.4kJ/mol for all classes of compound studied, indicating an important contribution from hydrophobic interactions to the overall binding. Plots for d-alkan-2-yl sulphate substrates and primary alkyl sulphate inhibitors were nearly coincident, suggesting that the overall interaction between a primary ester and the enzyme is the same as that between the isomeric secondary substrate and the enzyme. Plots for l-alkan-2-yl sulphate and alkanesulphonate inhibitors were very similar to each other, but were displaced by 1.5-3.0kJ/mol from that for substrate binding. This indicates that the binding of any one of these particular inhibitors involves one carbon atom fewer than the number involved in binding a substrate of the same chain length. These observations are discussed in terms of a three-point attachment of substrate to the enzyme involving the alkyl chain, sulphate group and the C-1 methyl group.

| S-EPMC1162237 | biostudies-other

Preparation and characterization of substrates suitable for the study of stereospecific secondary alkylsulphohydrolases of detergent-degrading micro-organisms.

Project description:During the course of the purification of novel stereospecific secondary aklylsulphohydrolases present in certain detergent-degrading micro-organisms, it became apparent that substrates prepared by sulphating secondary alcohols with H2SO4 are heterogeneous. Apart from the racemization that occurs if resolved alcohols are sulphated, evidence is provided to show that other isomers are produced in which the position of the ester sulphate group on the alkyl chain has been altered. These changes can be avoided if pyridine/SO3 reagent (prepared with SO3) is substituted as sulphating agent. Experiments in which secondary alkyl sulphates prepared by both methods were tested as potential substrates for the two secondary alkylsulphohydrolase enzymes of Comamonas terrigena have provided initial information about the specificity of the enzymes.

| S-EPMC1183719 | biostudies-other

Direct coupling of detergent purified human mGlu5 receptor to the heterotrimeric G proteins Gq and Gs.

Project description:The metabotropic glutamate (mGlu) receptors are class C G protein-coupled receptors (GPCRs) that modulate synaptic activity and plasticity throughout the mammalian brain. Signal transduction is initiated by glutamate binding to the venus flytrap domains (VFT), which initiates a conformational change that is transmitted to the conserved heptahelical domains (7TM) and results ultimately in the activation of intracellular G proteins. While both mGlu1 and mGlu5 activate G?q G-proteins, they also increase intracellular cAMP concentration through an unknown mechanism. To study directly the G protein coupling properties of the human mGlu5 receptor homodimer, we purified the full-length receptor, which required careful optimisation of the expression, N-glycosylation and purification. We successfully purified functional mGlu5 that activated the heterotrimeric G protein Gq. The high-affinity agonist-PAM VU0424465 also activated the purified receptor in the absence of an orthosteric agonist. In addition, it was found that purified mGlu5 was capable of activating the G protein Gs either upon stimulation with VU0424465 or glutamate, although the later induced a much weaker response. Our findings provide important mechanistic insights into mGlu5 G protein-dependent activity and selectivity.

| S-EPMC5849714 | biostudies-literature

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