DNA replication of SV40-infected cells. VII. Formation of SV40 catenated and circular dimers

The binding of methyl isonitrile (CH₃Nandz.tbnd;C) to hemoglobin β chains has been studied by measuring the ¹H nuclear magnetic resonance transverse relaxation times for methyl isonitrile as a function of protein concentration, temperature and ¹⁴N decoupling. Binding of methyl isonitrile both at the heme iron and at a non-specific site (or sites) has an effect upon the measured nuclear spin relaxation times. The results yield a value of 57 ± 12 seconds^?1 (20 °C) for the “off” rate constant K_?1 for specific binding and an Arrhenius activation energy for k_?1 of 14 ± 3 kcal mol^?1.     

Infrared and raman studies of the methyl cis undecenoates and of the methyl undecynoates

The infrared spectra (of CCl₄ solutions) and the Raman spectra (of the neat liquids) of the eight isomeric methyl cis-undecenoates, of methyl undec-10-enoate, and of the nine isomeric methyl undecynoates have been obtained. Conjugation of the double bond with the carbonyl group lowers the wavenumber value of ν(CC) by 8 cm^?1 from the mean value of 1657 cm^?1. Conjugation of the triple bond with the carbonyl group gives rise to a single Raman band due to ν(CC) at 2241 cm^?1 whereas the non-conjugated, non-terminal triple bond gives a Fermi resonance doublet at 2234 and 2293 cm^?1.     

Electron transfer from pyridinyl radicals, hydrated electrons, CO2.- and O2.- to bacterial cytochrome P450.

Several rate constants for one-electron reduction of cytochrome P450 are more rapid in the absence than in the presence of the specific substrate. The respective values for methyl viologen, nicotinamide adenine dinucleotide and the 1-methyl-4-(and -3-)carbamidopyridinium radicals are 2.6, 3.4, 6 and 35 × 10⁷ M^?1 s^?1 without camphor, and 0.15, 0.1, 1.8 and 110 × 10⁷ M^?1 s^?1 for the camphor complex. Hydrated electrons react with cytochrome P450 with a rate constant of 3.0 × 10¹⁰ M^?1 s^?1 whether camphor is bound or not, but little of the reduction takes place at the haem iron. No reduction of the haem iron by $\text{CO}{}_2{}^{\mathrm{?-}}$ or $\text{O}{}_2{}^{\mathrm{?-}}$ could be detected, whether camphor is bound or not.     

Esteroproteolytic enzymes from the submaxillary gland. Kinetics and other physicochemical properties.

Two esteroproteolytic enzymes (A and D) have been isolated from the mouse submaxillary gland and shown to be pure by ultracentrifugation, immunoelectrophoresis, acrylamide-gel electrophoresis, and amino acid analyses. The enzymes have molecular weights of approximately 30,000 and are structurally and antigenically related. Narrow pH optima between 7.5 and 8.0 are exhibited by both enzymes. The “pK₁'s” are between 6.0 and 6.5 and the “pK₂'s” are near 9.0. A marked preference for arginine-containing esters is shown by both enzymes. The maximum specific activity of enzyme A on p-tosylarginine methyl ester (TAME) at pH 8 was 2500–3000 μm min^?1 mg^?1 and for enzyme D, 400–600 μm min^?1 mg^?1. With TAME as substrate, the K_m for enzyme A was 8 × 10^?4m at 25 °C and 6 × 10^?4m at 37 °C. For D, K_m was 3 × 10^?4 at 25 °C and 2 × 10^?4m at 37 °C.An apparent activation of enzyme D by tosylarginine (TA), a product of TAME hydrolysis, and all α-amino acids examined was due to removal of an inhibitor by chelation. This effect could be duplicated by 8-hydroxyquinoline and diethyldithiocarbamate but not by EDTA. Enzyme A was not affected by these substances to any remarkable extent. Several divalent ions proved to be potent inhibitors of enzyme D. Both enzymes are inactivated by the active site reagents diisopropyl phosphofluoridate and tosyllysine chloromethylketone but much less rapidly than is trypsin. Nitrophenyl-4-guanidionobenzoate reacts with a burst of nitrophenol liberation but with a rapid continuing hydrolysis. One active site per molecule is indicated. Enzyme D is inactivated by urea, reversibly at 10 m and with maximal permanent losses at 6 m. Autolysis of the unfolded form by the native enzyme when they coexist at intermediate urea concentrations appears to occur.Identity of enzyme D and the epithelial growth factor binding protein is demonstrated.     

Accumulation of rosmarinic, chlorogenic and caffeic acids in in vitro cultures of Eryngium planum L.

Eryngium planum L. cell and organ cultures were maintained on Murashige and Skoog media (MS), supplemented with exogenous hormones of different types and various concentrations for high biomass growth. The callus and cell suspension cultures were treated with increased sucrose concentration and/or elicited by methyl jasmonate for the enhancement of selected phenolic acids accumulation. Three phenolic acids, rosmarinic acid (RA), chlorogenic acid (CGA) and caffeic acid (CA), were detected by HPLC-DAD in those cultures. The sum of their content in the dry material was found to be higher in the shoot culture (3.95 mg g^?1), root culture (7.05 mg g^?1), callus (6.20 mg g^?1) and cell suspension (2.04 mg g^?1) than in the leaves (1.87 mg g^?1) and roots (0.76 mg g^?1) of intact plants. The major compound of in vitro cultures was always rosmarinic acid. The content of RA could be increased approximately threefold (16.24 mg g^?1) in the callus culture and approximately twofold (3.91 mg g^?1) in the cell suspension culture by elicitation with 100 μM methyl jasmonate (MeJA). The higher concentration of sucrose (S) in the medium (5, 6 %) led to over a twofold increase of CGA content in the callus culture (2.54 mg g^?1). The three mentioned phenolic acids have been found in E. planum undifferentiated and differentiated in vitro cultures for the first time.     

The mixture of kresoxim‐methyl and boscalid,an excellent alternative controlling grey mould caused by Botrytis cinerea

Grey mould, caused by the fungus Botrytis cinerea, is one of the most destructive diseases in greenhouses for which serious fungicide resistance has developed. Between 2003 and 2005, 213 isolates of B. cinerea from two geographical regions were characterised for baseline sensitivity to kresoxim‐methyl. In the absence of salicylhydroxamic acid (SHAM), the mean 50% effective concentration (EC₅₀) values were 6.67 ± 0.61 (mean ± SD) and 0.37 ± 0.10 mg L^?1 during growth and germination, respectively. In the presence of 100 mg L^?1 SHAM, baseline sensitivities were distributed as unimodal curves with mean EC₅₀ values of 2.38 ± 0.21 and 0.28 ± 0.09 mg L^?1 for inhibiting growth and inhibiting germination, respectively. The mixture of kresoxim‐methyl and boscalid showed good control efficacy against strawberry grey mould disease. After the mixture was extensively used on strawberry for 2 years, 50 isolates were collected and determined for their sensitivity to kresoxim‐methyl and boscalid, respectively. The mean EC₅₀ of germination inhibition by boscalid was 0.39 ± 0.08 mg L^?1. The mean EC₅₀ of germination inhibition by kresoxim‐methyl was 0.26 ± 0.07 mg L^?1 in the presence of 100 mg L^?1 SHAM. Sensitivities of B. cinerea to both kresoxim‐methyl and boscalid did not show any significant decrease. These results suggest that their mixture is a satisfactory alternative candidate for management of grey mould disease in greenhouses.     

Superoxide formation in spinach chloroplasts: electron spin resonance detection by spin trapping.

The new technique of spin trapping has been applied to a biological system for the first time. The light induced generation of O₂^? by chloroplasts in the presence of oxygen has been shown by the production of the O₂^? adduct of the spin trap 5,5-dimethyl-1-pyrroline-1-oxide. The O₂^? adduct was detected by electron spin resonance spectroscopy. Methyl viologen enhanced the production of the O₂^? adduct thus providing support for the hypothes is that methyl viologen accepts electrons from the primary acceptor of photosystem I and subsequently reduces O₂ to O₂^?.     

Dynamic Structure of Proteins in Solid State. 1H and 13C NMR Relaxation Study

Abstract

Temperature dependencies of ¹H non-selective NMR T₁ and T₂ relaxation times measured at two resonance frequencies and natural abundance ^l3C NMR relaxation times T_l and T_lr measured at room temperature have been studied in a set of dry and wet solid proteins—;Bacterial RNase, lysozyme and Bovine serum albumin (BSA). The proton and carbon data were interpreted in terms of a model supposing three kinds of internal motions in a protein. These are rotation of the methyl protons around the axis of symmetry of the methyl group, and fast and slow oscillations of all atoms. The correlation times of these motions in solid state are found around 10^?11, 10^?9 and 10^?6 s, respectively. All kinds of motion are characterized by the inhomogeneous distribution of the correlation times. The protein dehydration affects only the slow internal motion. The amplitude of the slow motion obtained from the carbon data is substantially less than that obtained from the proton data. This difference can be explained by taking into account different relative inter- and intra- chemical group contributions to the proton and carbon second moments. The comparison of the solid state and solution proton relaxation data showed that the internal protein dynamics in these states is different: the slow motion seems to be few orders of magnitude faster in solution.     

Effect of azoxystrobin and kresoxim‐methyl on rice blast and rice grain yield in China

Sensitivity to azoxystrobin and kresoxim‐methyl of 80 single‐spore isolates of Magnaporthe oryzae was determined. The EC₅₀ values for azoxystrobin and kresoxim‐methyl in inhibiting mycelial growth of the 80 M. oryzae isolates were 0.006–0.056 and 0.024–0.287 µg mL^?1, respectively. The EC₅₀ values for azoxystrobin and kresoxim‐methyl in inhibiting conidial germination of the M. oryzae populations were 0.004–0.051 and 0.012–0.105 µg mL^?1, respectively. There was significant difference in sensitivity to azoxystrobin or kresoxim‐methyl between the tested isolates representing differential sensitivity to carbendazim (MBC) and kitazin P (IBP); however, there was no correlation between this difference in sensitivity to azoxystrobin or kresoxim‐methyl and sensitivity to MBC or IBP, indicating that there was no cross‐resistance between azoxystrobin or kresoxim‐methyl and MBC or IBP. In the protective and curative experiments, kresoxim‐methyl exhibited higher protective and curative activity than azoxystrobin when applied at 150 and 250 µg mL^?1 accordingly, while azoxystrobin exhibited stronger inhibitory activity against M. oryzae isolates than that of kresoxim‐methyl in the in vitro test. The results of field experiments also suggested that both azoxystrobin and kresoxim‐methyl at 187.5 g.a.i. ha^?1 gave over 73% control efficacy in both sites, exhibiting excellent activity against rice blast. Taken together, azoxystrobin and kresoxim‐methyl could be a good substitute for MBC or IBP for controlling rice blast in China, but should be carefully used as they were both at‐risk.     

Bacterial degradation of strobilurin fungicides: a role for a promiscuous methyl esterase activity of the subtilisin proteases?

Abstract

Strobilurin fungicides are some of the most heavily used antifungal chemicals in agriculture. However, little is known of their fate in the environment. We have identified bacteria that slowly transform strobilurin fungicides via hydrolysis of a methyl ester group in the toxophore, rendering them non-fungicidal. A carboxypeptidase (subtilisin Carlsberg) was found to have this activity, albeit with low specific activity (2.4 × 10^?2 nmol s^?1 mg^?1), and to possess specificity towards an analog of the fungicidal isomer of commercial strobilurins. Substrate-docking studies using the known structure for subtilisin Carlsberg revealed a plausible explanation for both the activity and isomer specificity of this class of hydrolase. These findings suggest that the promiscuous strobilurin methyl esterase activity of the subtilisin-like carboxypeptidases may have a role in the environmental fate of the strobilurin fungicides.     

Unraveling the stability of plasma proteins upon interaction of synthesized uridine products: biophysical and molecular dynamics approach

Abstract

Most of the drugs binding to human serum albumin (HSA) are transported to various parts of the body. Here, we have studied the molecular interaction between HSA and synthesized uridine derivatives, 1-[(3R, 4S, 5?R)-2-methyl-3, 4-dihydroxy-5-(hydroxymethyl)oxolan-2-yl]pyrimidine-2,4-dion.)(C-MU); [(2R,3R,4R,5R)-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-3,4-dihydroxy-4-methyl-tetrahydrofuran-2-yl] methyl methyl phosphochloridate (CM-MU) and [(2R,3S,4R,5R)-5-(2,4-dioxopyrimidin-1-yl)-2-methyl-3,4-dihydroxyoxolan-2-yl] methyl dihydrogen phosphate (P-MU). Cytotoxic studies of these synthesized compounds with mouse macrophages (RAW 246.7) and HeLa cells (human cervical cancer cells) and binding mechanism of these uridine derivatives with HSA were performed. Subsequently, fluorescence quenching was observed upon titration of uridine derivatives with HSA via static mode of quenching, and the binding constants (K_2-C-MU = 4?±?0.03?×?10⁴M^?1, K_5-CM-MU = 1.95?±?0.03?×?10⁴ M^?1 and K_5-P-MU =1.56?±?0.03?×?10⁴ M^?1) were found to be in sync with the computational results. Further, molecular displacement and molecular docking data revealed that all the derivatives are binding in the subdomain IIA and IIB regions of HSA. The protein secondary structure of complexes was determined by circular dichroism, indicating partial unfolding of the protein upon addition of the uridine derivatives. Furthermore, atomic force microscopy data reveal the change in topology upon binding of 2-C-MU, 5-CM-MU and 5-P-MU with HSA, indicating change in the microenvironment around tryptophan region. Additionally, cytotoxicity studies on HeLa and Raw Cell lines suggested that these molecules have significant anti-proliferative and anti-inflammatory properties. Hence, the study may be of help for development of new drugs based on uridine derivatives which may be helpful for combating various potential diseases.

Communicated by Ramaswamy H. Sarma     

Theoretical studies on the conformations of methyl glycopyranosides

The σ-charges on various atoms of methyl glycosides have been computed by using the MO-LCAO method of Del Re. The potential and free energies of methyl aldohexopyranosides and methyl aldopentopyranosides in their C1(d) and 1C(d) conformations have been calculated. Minimization of the energies of these conformations has been studied by suitably tilting the axial C-C and C-O bonds. Considerable release of strain is achieved when tilts of 4.5 and 3° are given to the axial hydroxymethyl and hydroxyl groups, respectively, that are involved in Hassel-Ottar effect. A tilt of 3° is also found necessary for the axial OMe group involved in the Hassel-Ottar effect. The calculated free-energy values are in accord with experimental ones, after adding a value of 0.8 kcal.mole^?1 for the anomeric effect of -OMe group. These studies predict that all of the methyl aldohexopyranosides, except methyl α-d- and methyl β-d-idopyranosides, favour the C1 conformation. On the other hand, the energy calculations also predict that, of the eight methyl aldopentopyranosides studied, only methyl α-d- and methyl β-d-xylopyranosides and methyl α-d -ribopyranoside favour the C1(d) conformation; for the other pentopyranosides, considerable amounts of both C1(d) and 1C(d) conformations are present in the equilibrium mixture. The calculated values of the percentage of α-anomer present in the equilibrium mixture agree fairly well with those obtained experimentally.     

A new approach to the characterization of the B and A forms of DNA by I.R. spectroscopy

The RNA conformational changes of B, A and C forms are reflected in the infrared absorption spectra in the region of 800 cm^?1 to 900 cm^?1 and allow one to investigate unoriented samples. The transition to the A form is characterized by the appearence of bands at about 870 cm^?1 and at 813 cm^?1 whereas the B and the C forms exhibit a band at 837 cm^?1, these bands undoubtedly arise from phosphate diester stretching vibrations and yield information about backbone conformation. The presence of these infrared bands provides a criterion for testing the simultaneous presence of two coexisting forms of DNA. It represents a useful method for structural studies of nucleic acid complexes such as protein-DNA for which it is difficult to obtain orientation.     

Striking susceptibility of a kinin-yielding pentadeca-peptide to tryptic hydrolysis

Hydrolysis of Lys-Arg-Pro-Gly-Phe-Ser-Pro-Phe-Arg-Ser-Val-Gln-Val-Ser by trypsin (EC 3.4.21.4) yields lysyl-bradykinin by rupture of the Arg-Ser bond. The k_cat/K_m value found for this hydrolysis was 1.4 × 10¹⁰ M^?1 × sec^?1, which is 10^?5-fold higher than that obtained for the hydrolysis of bradykinyl-Ser-Val-Gln-Val-Ser. This effect was abolished by acetylation of the lysine amino groups of the pentadecapeptide. Contrarywise, the esterolytic activity of trypsin on bradykinin methyl ester was the same as in lysyl-bradykinin methyl ester. The high susceptibility of Lys-bradykinyl-Ser-Val-Gln-Val-Ser to trypsin catalysis is striking because: a) it constitutes the first example that an amino acid residue distant from the bond split may enhance trypsin catalysis; b) this pentadecapeptide is the best synthetic substrate so far described for trypsin and c) the value of k_cat/K_m for its hydrolysis is unusually high for proteases.     

The vasorelaxant effect of (±)-15-deoxy-16-hydroxy-16(α/β)-vinyl-prostaglandin E2 (CL 115,129) and its methyl ester (CL 115,347) on the isolated ductus arteriosus preparation

CL 115,129 and its methyl ester, CL 115,347, were studied for their vasorelaxant effects and compared to that of prostaglandin (PG) E₂ and its methyl ester on isolated ductus arteriosus (DA) from fetal lambs and rabbits. CL 115,129 and CL 115,347 potently relaxed the oxygen-indomethacin constricted ductus in a concentration dependent manner. The threshold concentration was 1×10^?13M and the estimated EC₅₀'s (M) were 6.9×10^?8 and 4.3×10^?8, respectively, for CL 115,129 and CL 115,347. Also confirmed was the vasorelaxant ability of PGE₂. These studies indicate that the CL compounds possess potent vasorelaxant effects on the DA although less potent than PGE₂ or its methyl ester.     

Kinetic parameters for the binding of p-nitrophenyl alpha-d-mannopyranoside to concanavalin A.

Binding of the chromogenic ligand p-nitrophenyl α-d-mannopyranoside to concanavalin A was studied in a stopped-flow spectrometer. Formation of the protein-ligand complex could be represented as a simple one-step process. No kinetic evidence could be obtained for a ligand-induced change in the conformation of concanavalin A, although the existence of such a conformational change was not excluded. The entire change in absorbance produced on ligand binding occurred in the monophasic process monitored in the stopped-flow spectrometer. The value of the apparent second-order rate constant (k_a) for complex formation (k_a = 54,000 s^?1m^? at 25 °C, pH 5.0, Γ/2 0.5) was independent of the protein concentration when the protein was in the range of 233–831 μm in combining sites and in excess of the ligand. The apparent first-order rate constant (k_?a) for dissociation of the complex was obtained from the rate constant for the decomposition of the complex upon the addition of excess methyl α-d-mannopyranoside (k_?a = 6.2 s^?1 at 25 °C, pH 5.0, Γ/2 0.5). The ratio $\text{k}{}_{\mathrm{<mtext>a</mtext>}}{}_{\mathrm{<mtext>?</mtext><mtext>a</mtext>}}$ (0.9 × 10₄m^?1) was in reasonable agreement with value of 1.1 ± 0.1 × 10⁴m^?1 determined for the equilibrium constant for complex formation by ultraviolet difference spectrometry. Plots of ln($\text{k}{}_{\mathrm{<mtext>a</mtext>}}\text{T}$) and ln($\text{k}{}_{\mathrm{<mtext>a</mtext>}}\text{T}$) vs $\text{1}\text{T}$ were linear (T is temperature) and were used to evaluate activation parameters. The enthalpies of activation for formation and dissociation of the complex are 9.5 ± 0.3 and 16.8 ± 0.2 kcal/mol, respectively. The unitary entropies of activation for formation and dissociation of the complex are 2.8 ± 1.1 and 1.3 ± 0.7 entropy units, respectively. These entropy changes are much less than those usually associated with substantial changes in the conformation of proteins.     

Inhibition of two enzyme systems in Euchlanis dilatata (Rotifera: Monogononta) as biomarker of effect of metals and pesticides

The inhibitory effects on esterases and phospholipase A2 (PLA2) in the freshwater rotifer Euchlanis dilatata, native to Mexico, were assessed by fluorimetry after in vivo exposure (30?min) in laboratory conditions to sublethal concentrations of metals and pesticides. EC₅₀ values for esterases ranged from 7.9?×?10^?7 for DDT to 61.9 μg l^?1 for methyl parathion, while corresponding values for PLA2 ranged from 0.96?×?10^?6 for mercury to 69.2 μg l^?1 for lead. These enzyme systems in E. dilatata are very sensitive to the tested agents and suggest they would be suitable biomarkers. However, sensitivity to other environmental contaminants should be investigated in laboratory conditions and field studies to assess their potential as environmental biomarkers.     

Quantum-chemical and empirical calculations on phospholipids. III. Hydration of the dimethylphosphate anion

The binding of water to the dimethylphosphate anion (DMP^?) was calculated using the PCILO method. We found binding energies of 25.95 kcal·mol^?1 in the O1-P-O3 plane bridging the anionic oxygen atoms and 19.3 kcal·mol^?1 for the one-site association of a water molecule to an anionic oxygen atom of DMP^?. In this range one water molecule added to DMP^? in the O1 … O3 bridged configuration has a significantly higher binding energy to DMP^? than water molecules added to other binding sites. The total binding energy of 5 water molecules to DMP^? is 92 kcal·mol^?1, a quantity which is about 10% less than the sum of the binding energies of the corresponding monohydrates.     

Coidingham Loch, S.E. Scotland

SUMMARY. 1. Coidingham Loch (Berwickshire. Scotland) (area. 8.4 ha, mean depth 2.9 m, max. depth 12.3 m) belongs to Hakansson's convex shape category. It lies in a basin of Silurian Greywackes rock within 0.25 km of coastal sea cliffs (c. 133 m a.s.l.). The theoretical hydraulic replacement time is 3.17 years. 2. The loch stratifies intermittently in summer. Fluctuations in oxygen concentration generally correspond to spells of mixing and stratification; low values of 10% saturation occur at the bottom. 3. The sum of the concentrations of major cations (Na+, K+, Ca²⁺, Mg²⁺) is in accordance with measured conductivities ranging between 380 μS cm^?1 and 420 μS cm^?1 (k.₂₅). The ratios (by equivalents) of Na⁺/Cl^? (0.04) are similar to those in sea-water, whilst values for Ca+²⁺/Cl^? (0.85–1.01) and Mg²⁺/Cl^? (0.79–0.88) reflect the bedrock. 4. Nitrate concentrations were lowest (<0.05 mg N1^?1) in summer following losses from the column of 107 mg N m^?2 1^?1, a rate corresponding well with published figures on microbial nitrate reduction. Nitrate increased at a rate of 8μg N I^?1 d^?1 to a winter maximum of 1.55 mg N I^?1. Mass balance calculations show that if this rise is attributed to run-off from surrounding land, a loss rate of 11.1 kg N ha^?1 yr^?1 would be required; this value is also commensurate with published figures. 5. Changes in phosphorus and factors controlling them contrast markedly with those of nitrate. The minimum concentration of 55 μg total P l^?1 (mainly in soluble reactive form) occurs in spring. An increase to the maximum ofc. 300 μg l^?1 in summer is sustained mainly by release from the sediments at a regular rate of 3 μg P l^?1 d^?1 (8.7 mg m^?2 d^?1). Adsorption by the sediments is considered to be the major process accounting for autumnal losses of phosphorus of 2.6 mg P M^?2d^?1. 6. Silica showed a less regular seasonal pattern, but varied some 45-fold with a maximum of 2.25 mg SiO₂, l_?1 in August.     

Parameters affecting productivity in the lipase-catalysed synthesis of sucrose palmitate

The industrial application of lipases for the synthesis of sucrose esters is usually limited by its low productivity, as we need a medium where a polar reagent (the sugar) and a non-polar fatty acid donor are soluble and able to react in the presence of the biocatalyst. In this work, we have studied the problems encountered when trying to increase the volumetric productivity of sucrose esters. The synthesis of sucrose palmitate was performed in 2-methyl-2-butanol:dimethylsulfoxide mixtures by transesterification of different palmitic acid donors with sucrose, catalysed by the immobilized lipase from Candida antarctica B (Novozym 435). A protocol for substrate preparation different from that previously reported was found to improve the reaction rate. Several parameters, such as sucrose and acyl donor loadings, the percentage of DMSO in the mixture and the nature of acyl donor, were investigated. Under the best experimental conditions (15% DMSO, 0.1 mol l^?1 sucrose, 0.3 mol l^?1 vinyl palmitate), a maximum of 45 g l^?1 sucrose palmitate was obtained in 120 h. Using methyl or ethyl palmitate, the highest productivity was 7.3 g l^?1 in 120 h using 20% DMSO with 0.2 mol l^?1 sucrose and 0.6 mol l^?1 acyl donor. The formation of free fatty acid, and the effect of the percentage of DMSO on the monoester/diester selectivity were also studied. To our knowledge, this is the first report on enzymatic synthesis of sucrose esters of long fatty acids using alkyl esters as acyl donors.