Differences In Rates Of Hydrolysis Research Articles

Apolipoprotein E content of VLDL limits LPL-mediated triglyceride hydrolysis

High levels of circulating triglycerides (TGs), or hypertriglyceridemia, are key components of metabolic diseases, such as type 2 diabetes, metabolic syndrome, and CVD. As TGs are carried by lipoproteins in plasma, hypertriglyceridemia can result from overproduction or lack of clearance of TG-rich lipoproteins (TRLs) such as VLDLs. The primary driver of TRL clearance is TG hydrolysis mediated by LPL. LPL is regulated by numerous TRL protein components, including the cofactor apolipoprotein C-II, but it is not clear how their effects combine to impact TRL hydrolysis across individuals. Using a novel assay designed to mimic human plasma conditions in vitro, we tested the ability of VLDL from 15 normolipidemic donors to act as substrates for human LPL. We found a striking 10-fold difference in hydrolysis rates across individuals when the particles were compared on a protein or a TG basis. While VLDL TG contents moderately correlated with hydrolysis rate, we noticed substantial variations in non-apoB proteins within these particles by MS. The ability of LPL to hydrolyze VLDL TGs did not correlate with apolipoprotein C-II content, but it was strongly inversely correlated with apolipoprotein E (APOE) and, to a lesser extent, apolipoprotein A-II. Addition of exogenous APOE inhibited LPL lipolysis in a dose-dependent manner. The APOE3 and (particularly) APOE4 isoforms were effective at limiting LPL hydrolysis, whereas APOE2 was not. We conclude that APOE on VLDL modulates LPL activity and could be a relevant factor in the pathogenesis of metabolic disease.

Forecasting linear aliphatic copolyester degradation through modular block design

The development of efficient methods to predict the degradation of renewable polymeric materials is continuously sought in the field of polymer science. Herein, we present a modular build-up approach to create polyester-based materials with forecasted degradation rates based on the hydrolysis of the constituent polymer blocks. This involved the strategic combination of critical factors affecting polyester hydrolysis, i.e. hydrophobicity and degree of crystallinity. The starting point of this method was a toolbox of polymers with different hydrophobicities and degrees of crystallinity, as well as an understanding of their inherent differences in hydrolysis rate. Knowledge of the hydrolysis of each polymer block module enabled the prediction of the overall degradation behavior of the constructed copolymers. Taking advantage of the primary factors that affect polymer degradation, block copolymers could be independently designed to incorporate soft or rigid and faster or slower degradation properties. This approach generated a shift for how molecular design can be used to predict the degradation behavior of intended materials for different applications.

Textural and morphological studies of transition metal doped SBA-15 by co-condensation method

The 3d transition metals were incorporated into SBA-15 matrix by co-condensation synthesis method. Very low concentrations of metals were introduced into silica framework by maintaining the metal to silica ratio in the synthesis gel at 0.01. The difference in hydrolysis rates of metal and silica precursors have led to textural modifications while demonstrating the structural integrity akin to pristine SBA-15. The physicochemical properties obtained offer some insights into the P123 micelle aggregation and mechanism of formation of silica network in the presence of metal salts under similar synthesis conditions of pure SBA-15. The metal doping into SBA-15 leads to increased pore diameters. Higher lattice constants (a0) observed in these samples are attributed to the increased pore wall thickness. The significant retention of the hexagonal mesostructure seen in LXRD indicates diminutive influence of metal salts at lower concentrations. Macroscopic morphologies studied by SEM show the formation of spheres along with conventional fibre-like rods. The 3d-transition metals were incorporated in SBA-15 by co-condensation method. The structural and textural properties of modified SBA-15 materials elucidate the increased pore wall thickness besides retaining their typical two dimensional hexagonal mesochannels with p6mm symmetry. The metal dopants have promoted the condensation of silica and induced morphological changes.

Unprecedented reactivity of alkoxo/hydroxide-bridged dinuclear copper(II) complexes as artificial carboxylesterase: Effects of Gemini 16-6-16 micelles and bimetallic synergistic effect

One μ-alkoxo/hydroxide-bridged dinuclear copper(II) complex (Cu2L) and a mononuclear analogue (CuL) with symmetric Schiff base compound were employed as carboxylesterase models to promote the hydrolysis of a carboxylic acid ester, p-nitrophenyl picolinate (PNPP). Also the introducing of a Gemini surfactant, bis(hexadecyldimethylammonium)hexane bromide (16-6-16, 2Br−), gave interested observations relative to those controlled trials preformed in buffer and a micellar solution of traditional single-chain surfactant, CTAB (cetyltrimethylammonium bromide). The results indicated that the dinuclear Cu2L efficiently accelerated PNPP hydrolysis with 18,096- and 49,569.6-fold rate enhancement under moderate conditions (pH 7.00, 25°C) in buffer and 16-6-16 micellar solution, respectively. Much greater rate enhancement was observed in 16-6-16 micelles in contrast with CTAB micelles, launching 1.6–2.6 folds difference in hydrolysis rate of PNPP at pH 7.00. Additionally, the Cu2L-induced PNPP hydrolysis showed a bell-shaped rate-pH profile, which is an enzyme-like behaviour. Interestingly, rate–pH curves could provide the direct evidence for the interfacial effects of Gemini 16-6-16 micelles on the deprotonation of coordinated water, indicating about 0.2 unit pKa1 difference of the Cu2L-bound H2O between in micellar phase and bulk phase. Cu2L was found to be approximately 199.3- and 288.7-fold reactive than CuL in buffer and 16-6-16 micellar solution, respectively. Significant activity difference between both complexes probably results from the bimetallic coorperation of the two catalytic copper sites and more open binding site of Cu2L.

C2 Hydroxyl Group Governs the Difference in Hydrolysis Rates of Methyl-α-d-glycero-d-guloseptanoside and Methyl-β-d-glycero-d-guloseptanoside

A computational investigation into the hydrolysis of two methyl septanosides, methyl-α-D-glycero-D-guloseptanoside and methyl-β-D-glycero-D-guloseptanoside was undertaken. These septanosides were chosen as model compounds for comparison to methyl pyranosides and allowed direct comparison of α versus β hydrolysis rates for a specific septanoside isomer. Results suggest that hydrolysis takes place without proceeding through a transition state, an observation that was suggested in previous computational studies on exocyclic bond cleavage of carbohydrates. A conformational analysis of α- and β-anomers 1 and 2 and their corresponding oxocarbenium 3, coupled with relaxed potential energy surface (PES) scans (M06-2X/6-311+G**, implicit methanol), indicated that hydrolysis of the α-anomer is favored by 1-2 kcal/mol over the β-anomer, consistent with experiment. Model systems revealed that the lowest energy conformations of the septanoside ring system destabilize the β-anomer by 2-3 kcal/mol relative to the α-anomer, and the addition of a single hydroxyl group at the C2-position on a minimal oxepane acetal can reproduce the PES for the septanoside 1. These results suggest that the C2 hydroxyl plays a unique role in the hydrolysis mechanism, destabilizing the septanoside via its proximity to the anomeric carbon and also through its interaction with the departing methanol from the α-anomer via hydrogen-bonding interactions.

Mechanistic approach of the difference in non‐enzymatic hydrolysis rate between the L and D enantiomers of no‐carrier added 2‐[18F]fluoromethyl‐phenylalanine

AbstractNo‐carrier added (n.c.a.) 2‐[18F]fluoromethyl‐l‐phenylalanine was found to be very sensitive to hydrolysis in aqueous solutions. This problem was solved partially by the addition of calcium ions (0.04 M), increasing the shelf‐life to at least 6 h. In this paper the defluorination reaction was studied in detail to elucidate its mechanism. Therefore, L and D enantiomers of 2‐[18F]FMP and 4‐[18F]FMP were synthesized, as well as 2‐[18F]fluoromethyl‐phenethylamine and 4‐[18F]fluoromethyl‐phenethylamine, both decarboxylated ‘mimetic’ molecules of the amino acid analogues. Radiosynthesis, using a customized Scintomics automatic synthesis hotboxthree module, resulted in a high overall yield and a radiochemical purity of >99%. The defluorination rates of all compounds were studied by HPLC. The L enantiomer of n.c.a 2‐[18F]FMP defluorinated seven times faster than the D enantiomer and 2‐[18F]fluoromethyl‐phenethylamine. Both enantiomers of 4‐[18F]FMP and 4‐[18F]fluoromethyl‐phenethylamine were stable. From these data, the reaction mechanism, involving two distinct intramolecular interactions, was derived. First, the interaction between the amine and the benzylic fluorine weakens the carbon–fluorine bond. Secondly, the formation of a second hydrogen bridge between the carboxyl group and one of the benzylic hydrogen atoms renders the fluorine atom even more susceptible to hydrolysis. The latter interaction induces an additional chiral center. The probability of its formation differs considerably between L and D enantiomers of n.c.a. 2‐[18F]FMP, which explains the difference in hydrolysis rate. Copyright © 2010 John Wiley & Sons, Ltd.

Biochemical and biological evidence of the activity of high potencies

1. A method is described for investigating the possible action of microdoses of mercuric chloride on the hydrolysis of soluble starch with malt diastase. 2 The microdoses of the mercuric chloride used in the latest crucial series carried out in 1946, 1948, and 1952, were what are termed ‘high potencies’ made in accordance with the pharmaceutical method of preparation of drags ordinarily used in the practice of homceotherapy. 3 These microdoses were prepared by separate stages of dilution, the solution at each stage being subjected to mechanical shock. The solutions were, theoretically, ‘dilutions’ of the order of 1 in 10−61 and on present physical theory would not contain any molecules of the original mercuric chloride. 4 The difference in rate of hydrolysis between flasks containing starch, diastase, and distilled water (controls) and flasks containing starch, diastase and microdoses of mercuric chloride (tests) were compared colorimetrically by the Spekker absorptiometer, and the frequencies of the differences statistically analysed, as the results obtained showed biological scatter. More than 500 such comparisons were carried out. The differences of means were examined by the Fisher “t” test, the variances tested and Cochrane and Cox’s test applied where indicated. All the series gave a highly significant difference in the rate of hydrolysis between controls and tests, the microdoses stimulating the process. Statistically the significance is shown by the fact that a probability of 5 The distribution, control methods, and accessory control procedures were considered to exclude, as a cause of the effects, adsorption of the original drug and the presence of extraneous contaminants by chance solely in test flasks. The only difference between control and microdose flasks was the addition of microdose, the distilled water being common to both controls and tests. 6 It was concluded that a factor, unidentified, derived from the mercuric chloride used, was present in solutions prepared by serial dilution with mechanical shock which could affect the distilled water diluent, that this change was transferable to subsequent ‘ultra-molecular’ stages of ‘dilution’, and that this factor was the source of the activity in the microdose solutions producing the acceleration of the rate of hydrolysis. 7 In an addendum there is described recent biological work which is also providing evidence of the presence of an active selective factor in ‘high potencies’ derived from Strophanthus sarmentosus by the same methods of dilution with mechanical shock.

Effect of mixing on enzymatic hydrolysis of steam-pretreated spruce: a quantitative analysis of conversion and power consumption

BackgroundWhen scaling up lignocellulose-based ethanol production, the desire to increase the final ethanol titer after fermentation can introduce problems. A high concentration of water-insoluble solids (WIS) is needed in the enzymatic hydrolysis step, resulting in increased viscosity, which can cause mass and heat transfer problems because of poor mixing of the material. In the present study, the effects of mixing on the enzymatic hydrolysis of steam-pretreated spruce were investigated using a stirred tank reactor operated with different impeller speeds and enzyme loadings. In addition, the results were related to the power input needed to operate the impeller at different speeds, taking into account the changes in rheology throughout the process.ResultsA marked difference in hydrolysis rate at different impeller speeds was found. For example, the conversion was twice as high after 48 hours at 500 rpm compared with 25 rpm. This difference remained throughout the 96 hours of hydrolysis. Substantial amounts of energy were required to achieve only minor increases in conversion during the later stages of the process.ConclusionsImpeller speed strongly affected both the hydrolysis rate of the pretreated spruce and needed power input. Similar conversions could be obtained at different energy input by altering the mixing (that is, energy input), enzyme load and residence time, an important issue to consider when designing large-scale plants.

Mechanistic approach of the difference in hydrolysis rate between the 2‐ and 4‐isomers of no‐carrier‐added [18F]fluoromethyl‐L‐phenylalanine

AbstractNo‐carrier‐added (n.c.a.) 2‐[18F]fluoromethyl‐l‐phenylalanine (2‐[18F]FMP) was found to be very sensitive to hydrolysis in aqueous solutions. In this paper, the defluorination reaction was studied in detail to elucidate its mechanism. Therefore, besides 2‐[18F]FMP and 4‐[18F]FMP, 2‐[18F]fluoromethyl‐phenethylamine (2‐[18F]FMPAM) and 4‐[18F]FMPAM were synthesized, both ‘mimetic’ molecules of the decarboxylated amino acid analogues. Radiosynthesis, using a customized Scintomics automatic synthesis hotboxthree module, resulted in a high overall yield and a radiochemical purity of >99%. The defluorination rates of all compounds were studied by HPLC. The defluorination rate of 2‐[18F]FMLP at 50°C was approximately 300 times faster than that of n.c.a. 4‐[18F]FMLP. The defluorination rate of 2‐[18F]FMPAM is somewhat lower than of 2‐[18F]FMP but still very high in comparison with 4‐[18F]FMPAM, which is virtually stable. It allowed to elucidate the reaction mechanism ruled by two distinct intramolecular interactions. First, the hydrogen bond interaction between the amine and the benzylic fluorine weakening the carbon–fluorine bond. Secondly, the formation of a second hydrogen bond between the carboxyl oxygen atom and one of the benzylic hydrogen atoms rendering the benzyl fluoride group even more susceptible to hydrolysis. Copyright © 2010 John Wiley & Sons, Ltd.

Critical importance of loop conformation to avidin-enhanced hydrolysis of an active biotin ester

The homotetrameric and biotin-binding properties of avidin and streptavidin have been exploited for a myriad of biotechnological applications and theoretical studies. Among the few differences between the two proteins is the capacity of avidin to hydrolyze biotinyl p-nitrophenyl ester (BNP), as opposed to streptavidin, which fully protects the same pseudosubstrate from hydrolysis. Combined mutagenesis and X-ray analysis have been used to attempt to understand this diametric difference in activities. It was found that a charged residue and one of the loops (L3,4) are together responsible for this difference. Recently, the avidin-related analogue AVR4 was found to have an even more pronounced BNP-hydrolysis activity than avidin. Again, the combination of charged residue(s) (Asp39 and/or Arg112) and the rigid conformation of the L3,4 loop was suggested to be responsible for the observed hydrolysis reaction. However, replacement of the latter charged residues in AVR4 resulted in only a modest reduction in hydrolytic activity at most, whereas replacement of the L3,4 loop of avidin with the rigid loop of AVR4 caused a dramatic increase in the activity of avidin. These results clearly demonstrate that the main feature responsible for the observed differences in rates of hydrolysis among the avidins is the conformational status of the L3,4 loop, which imposes conformational constraints on the pseudosubstrate, thereby rendering it susceptible to nucleophilic attack by solvent. In this context, the hydrolytic properties of the avidins reflect enzyme catalysis, in that subtleties in substrate binding are the determining features of catalytic efficiency.

Synthesis and Evaluation of Biocompatible pH-Sensitive Hydrogels as Colon-Specific Drug Delivery Systems

Because of the growing importance of pH-sensitive hydrogels as drug delivery systems, biocompatible copolymeric hydrogels based N-vinyl-2-pyrrolidinone (NVP) and methacrylic acid (MAA) were designed and synthesized. These hydrogels were investigated for oral drug delivery. Radical copolymerizations of N-vinyl-2-pyrrolidinone (NVP) and methacrylic acid (MAA) with the various ratios of cross-linking agent were carried out at 70 °C. Azabisisobutyronitrile (AIBN) was the free-radical initiator employed and Cubane-1,4-dicarboxylic acid (CDA) linked to two 2-hydroxyethyl methacrylate (HEMA) group was the crosslinking agent (CA) used for hydrogel preparations. The hydrogels were characterized by differential scanning calorimetry and FT-IR. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). A model drug, olsalazine [3,3′-azobis (6-hydroxy benzoic acid)] (OSZ) as an azo derivative of 5-aminosalicylic acid (5-ASA), was entrapped in these gels and the in-vitro release profiles were established separately in both enzyme-free SGF and SIF. The drug-release profiles indicated that the amount of drug released depended on the degree of swelling. The swelling was modulated by the amount of crosslinking of the polymer bonded drug (PBDs) prepared. Based on the great difference in hydrolysis rates at pH 1 and 7.4, these pH-sensitive hydrogels appear to be good candidates for colon-specific drug delivery.

Jacobs wins Dow contract for new PET facility

1.1. Aminopeptidases hydrolysing l-alanine-β-naphthylamide (AlaNA), l-arginine-β-naphthylamide (ArgNA) and l-leucine-β-napthylamide (LeuNA) were studied in homogenate and after fractionation (gel filtration, chromatofocusing) of various parts of the rat prostatic complex (ventral lobe, VP; lateral lobe. LP; posterior lobe, PP; coagulating gland, CG) and seminal vesicles (VS).2.2. Marked differences were observed in the hydrolysis rates of these substrates in the various tissues studied.3.3. After fractionation up to seven activities were separated with differences in pH-optima. pI-values, molecular weights, substrate preferences and modifier characteristics.4.4. The number of enzyme activities characteristically varied between the tissues studied. Depending on the enzyme pattern in each part the differences in hydrolysis rates of the three substrates became apparent.

Enzymes and chelating agent in cotton pretreatment

Desized cotton fabric and cotton seed-coat fragments (impurities) have been treated with commercial cellulase (Celluclast 1.5 L), hemicellulase–pectinase (Viscozyme 120 L) and xylanase (Pulpzyme HC) enzymes. Seed-coat fragments hydrolyzed much faster than the cotton fabric itself. This relative difference in hydrolysis rates makes possible a direct enzymatic removal of seed-coat fragments from desized cotton fabric. Addition of chelating agents such as ethylenediamine-tetra-acetic acid (EDTA) markedly enhanced the directed enzyme action. Pretreatments carried out in acidic solution at pH 5 increased the lightness of seed-coat fragments, contrary to the samples treated in neutral medium at pH 7. Alkaline scouring resulted in darker seed-coat fragments except for the samples pretreated with Pulpzyme HC plus EDTA. This effect is similar to that observed in the biobleaching process in pulp and paper industry.

Changes in hydrolysis specificities of lipase from Rhizomucor miehei to polyunsaturated fatty acyl ethyl esters in different aggregation states

AbstractHydrolysis specificities of lipase from Rhizomucor miehei were compared for various fatty acyl ethyl esters. Activity yields of immobilized lipases, measured with 1 mM substrate, were more than 100%. Differences in hydrolysis rate and affinity for the substrates between lipase preparations were also typically higher during hydrolysis of substrates at 100 mM than at 1 mM, indicating better mass transfer effects for 1‐mM substrates. The native lipase showed higher affinity for polyunsaturated fatty acid substrates at 1 mM than at 100 mM. Hydrolysis rates for 1‐mM substrates were observed with immobilized lipases, fixed on anion exchange resin with glutaraldehyde and on cation exchange carrier with carbodiimide, and suggested some modification of the basic amino acid related to the lid of R. miehei lipase. Activation with these bifunctional reagents was not observed for 100‐mM substrates, indicating that interfacial activation always occurred because of aggregation of 100‐mM substrates. These results show that lipase from R. miehei recognizes molecular aggregation of lipids, and that various changes occur in the hydrolysis specificities for fatty acids.

Lipase-catalysed enantioselective hydrolysis: Interpretation of the kinetic results in terms of frontier orbital localisation

Abstract The initial velocities of the enantioselective hydrolysis of the esters derived from mono- and bicyclic alcohols and hemiacetals catalysed by Lipolase™ in water have been determined. The differences in hydrolysis rates within groups of sterically similar substrates have been interpreted in terms of frontier orbital localisation.

Differences in rate of hydrolysis of HMG-CoA reductase inhibitors in human and animal tissues

Differences in rate of hydrolysis of HMG-CoA reductase inhibitors in human and animal tissues

Covalent binding properties of the human complement protein C4 and hydrolysis rate of the internal thioester upon activation

The complement proteins C3 and C4 have an internal thioester. Upon activation on the surface of a target cell, the thioester becomes exposed and reactive to surface-bound amino and hydroxyl groups, thus allowing covalent deposition of C3 and C4 on these targets. The two human C4 isotypes, C4A and C4B, which differ by only four amino acids, have different binding specificities. C4A binds more efficiently than C4B to amino groups, and C4B is more effective than C4A in binding to hydroxyl groups. By site-directed mutagenesis, the four residues in a cDNA clone of C4B were modified. The variants were expressed and their binding properties studied. Variants with a histidine residue at position 1106 showed C4B-like binding properties, and those with aspartic acid, alanine, or asparagine at the same position were C4A-like. These results suggest that the histidine is important in catalyzing the reaction of the thioester with water and other hydroxyl group-containing compounds. When substituted with other amino acids, this reaction is not catalyzed and the thioester becomes apparently more reactive with amino groups. This interpretation also predicts that the stability of the thioester in C4A and C4B, upon activation, will be different. We measured the time course of activation and binding of glycine to C4A and C4B. The lag in the binding curve behind the activation curve for C4A is significantly greater than that for C4B. The hydrolysis rates (k0) of the thioester in the activated proteins were estimated to be 0.068 s-1 (t1/2 of 10.3 s) for C4A and 1.08 s-1 (t1/2 of 0.64 s) for C4B. These results indicate that the difference in hydrolysis rate of the thioester accounts, at least in part, for the difference in the binding properties of C4A and C4B.

13CO2 breath test to measure the hydrolysis of various starch formulations in healthy subjects.

13CO2 starch breath test was used to study the effect of physicochemical characteristics of starch digestion. As starch is hydrolysed to glucose, which is subsequently oxidised to CO2, differences in 13CO2 excretion after ingestion of different starch products must be caused by differences in hydrolysis rate. To study the effect of the degree of chain branching, waxy starch, containing 98% amylopectin, was compared with high amylose starch, containing 30% amylopectin, and normal crystalline starch, containing 74% amylopectin. The effect of the extent of gelatinisation was studied by comparing extruded starch and crystalline starch. Finally, the possible inhibitory effect of adding wheat fibre to extruded starch on the hydrolysis rate was studied. The 13CO2 excretion from two to four hours after intake of crystalline starch was significantly lower than that of extruded starch. Waxy starch was hydrolysed much faster than high amylose starch, but there was no significant difference between waxy starch and normal crystalline starch. Addition of wheat fibre did not influence the hydrolysis rate. The 13CO2 starch breath test is an attractive test for the study of factors affecting carbohydrate assimilation.

Forage Source and Maturity Effects on Enzymatic Digestion Rate of Isolated Cellulose

This study was conducted to determine the rate of enzymatic hydrolysis of isolated cellulose from grass and legume forages important to the southeastern USA, and to compare the difference in hydrolysis rate between grasses and legumes at two stages of maturity. Cellulose from six grass and nine legume species harvested at two stages of maturity were isolated using an acid chlorite delignification procedure followed by hemicellulose extraction with 0.12 M NaOH solution. Residual dry matter from isolated cellulose samples was determined to contain between 901 and 958 g kg− glucose. Cellulose samples were incubated at 40°C in a solution of commercially obtained cellulose enzyme for 8 h. Solutions were sampled at hourly intervals and analyzed for glucose concentration. Results indicated that glucose production was linear during the sampling period for all cellulose samples. The rate of enzymatic hydrolysis was greater (P < 0.01) for cellulose isolated from grass samples than from legume samples (8.06 and 6.94 mg kg 1 s 1, respectively). Stage of maturity also affected enzymatic digestion rate (P < 0.01). Rates for enzymatic digestion of cellulose from immature and mature forage were 8.61 and 8.06 mg kg 1 s 1, respectively. Even though enzymatic digestion rates between grasses and legumes were significantly different, the differences were small. Correlation between cellulose digestion rate and in vitro dry matter digestion of forage was not significant, indicating that cellulose digestion rate was not important in determining digestibility of whole plant tissue.

Reactivity of carboxylic acid and ester groups in the functionalized interfacial region of "polyethylene carboxylic acid" (PE-CO2H) its derivatives: differentiation of the functional groups into shallow and deep subsets based on a comparison of contact angle and ATR-IR measurements

We have differentiated the carboxylic acid groups present in the functionalized interface of “polyethylene carboxylic acid” (PE4O2H, a material prepared from low-density polyethylene film by reaction with aqueous chromic acid) into two subsets: those sufficiently close to the surface of the polymer to influence its wettability by water and those too deep to do so. This differentiation was accomplished by taking advantage of differences in rates of esterification of carboxylic acid groups in different regions of the functionalized interface and of differences in rates of hydrolysis of ester groups derived from them. The subset of functional groups influencing wettability comprises <30% of the total groups present in the functionalized interface and appears to be homogeneous in its chemical reactivity. The remaining groups (-70% of the total) do not directly influence wettability and appear to become less reactive with increasing depth in the polymer. The surface and subsurface carboxylic acid and ester moieties are both less reactive in hydrolysis and formation reactions than are these groups in organic molecules in solution. Reactivities of the interfacial functional groups depend on structure in ways having no analogy in reactions in solution. For example, the rate of base-catalyzed hydrolysis of esters present in the functionalized polymer interface is a strong function of the length of the alcohol component of the ester: n-octyl esters are more than 20000 times less reactive than methyl esters. We have also explored the acidity of the interfacial carboxylic acid groups using ATR-IR spectroscopy and contact angle measurements as probes. Both the local polarity of the environment of individual carboxylic acid groups and charge-charge interactions between carboxylate anions appear to be important in determining acidity. Comparisons of wettability of samples containing different proportions of carboxylic acid, carboxylate anion, and ester groups indicate that wettability is particularly sensitive to low concentrations of carboxylate anion. We hypothesize that this sensitivity reflects a limited ability of the functionalized interfacial region to reconstruct-perhaps only by small-amplitude rotations of its constituent carboxylate ions-in a way that minimizes its free energy by maximizing the number of these hydrophilic moieties in direct contact with the polar, aqueous liquid phase.