Structure of lintnerized starch is related to X-ray diffraction pattern and susceptibility to acid and enzyme hydrolysis of starch granules

Acid-resistant residues (lintnerized starches, Ls) were prepared from starches showing A-, B- and C- X-ray diffraction patterns. Ls retained the same X-ray crystalline type as their native counterparts with an improvement in diffraction intensity. Fluorophore-assisted capillary electrophoresis (FACE) study indicated that structural characteristics of Ls were associated with X-ray diffraction patterns. Double helices originated from linear chains with an approximate average degree of polymerisation (DP) 14, 16, and 15 would span the entire length of crystalline lamellae of A-, B-, and C-type starches, respectively. The proportion of singly branched materials (SB) with DP 25 protected in Ls was higher for A-type Ls (10-17%) than for B-type Ls (4-6%) and C-type Ls (8%). The structures of SB were similar in which branched chain (DP 13-15) was longer than main chain (DP 10-12). The structural characteristics of Ls are discussed in relation to acid and enzymatic degradations of starch granules.     

Amylopectin molecular structure reflected in macromolecular organization of granular starch

For lintners with negligible amylose retrogradation, crystallinity related inversely to starch amylose content and, irrespective of starch source, incomplete removal of amorphous material was shown. The latter was more pronounced for B-type than for A-type starches. The two predominant lintner populations, with modal degrees of polymerization (DP) of 13-15 and 23-27, were best resolved for amylose-deficient and A-type starches. Results indicate a more specific hydrolysis of amorphous lamellae in such starches. Small-angle X-ray scattering showed a more intense 9-nm scattering peak for native amylose-deficient A-type starches than for their regular or B-type analogues. The experimental evidence indicates a lower contrasting density within the "crystalline" shells of the latter starches. A higher density in the amorphous lamellae, envisaged by the lamellar helical model, explains the relative acid resistance of linear amylopectin chains with DP > 20, observed in lintners of B-type starches. Because amylopectin chain length distributions were similar for regular and amylose-deficient starches of the same crystal type, we deduce that the more dense (and ordered) packing of double helices into lamellar structures in amylose-deficient starches is due to a different amylopectin branching pattern.     

Amylose–lipid complexation: a new fractionation method

Amylose fractions of different peak Degree of Polymerisation (DP) (DP20, DP60, DP400, DP950) were complexed with docosanoic acid (C22) and glyceryl monostearate (GMS) at 60 and 90 °C. Complexation yields, relative crystallinities, dissociation temperatures and enthalpies increased with amylose chain lengths (DP20–DP60–DP400). Relative crystallinities and thermal stabilities of the DP950-complexes were slightly lower than those of the other amylose fractions, probably due to increased conformational disorders, resulting in crystal defaults. Molecular weight distributions of the complexes revealed that, irrespective to the complexation temperature, the critical DP for complex formation and precipitation was 35 and 40 for complexes with GMS and C22, respectively, corresponding to the length needed to accommodate two GMS- or C22-molecules within an amylose helix. Complexation of dextrins with a well-chosen lipid, allows to separate starch derived dextrins with a predictable critical chain length as border. Dextrins, of sufficient DP will complex and precipitate, while the shorter dextrins will remain in solution.     

Glycosaminoglycan destabilization of DNA–chitosan polyplexes for gene delivery depends on chitosan chain length and GAG properties

Chitosan-based gene delivery systems are promising candidates for non-viral gene therapy. A wide range of chitosans has been studied to optimize the properties of the DNA–chitosan complexes to yield high transfection efficiencies. An important parameter to control is the polyplex stability to allow transport towards the cells, subsequent internalization and release of DNA intracellularly. The stability of the DNA–chitosan complexes was here studied after exposure to heparin and hyaluronic acid (HA) using atomic force microscopy (AFM) and ethidium bromide (EtBr) fluorescence assay. To study the effect of polycation chain length on the polyplex stability, chitosans with a degree of polymerization (DP) varying from ∼10 to ∼1000 were employed for DNA compaction. Whereas HA was unable to dissociate the complexes, the degree of dissociation caused by heparin depended on both the chitosan chain length and the amount of chitosan used for complexation. When increasing the chitosan concentration, larger heparin concentrations were required for polyplex dissociation. Furthermore, increasing the chitosan chain length yielded more stable complexes. Varying the chitosan chain length thus provides a tool for controlling the ability of the polyplex to deliver therapeutic gene vectors to cells.     

Mechanism of cellulase reaction on pure cellulosic substrates

Cellulase reaction mechanism was investigated with the use of following pure cellulosic substrates: Microcrystalline cellulose (Avicel), α‐cellulose (Sigma), filter paper, cotton, and non‐crystalline cellulose (NCC). NCC is amorphous cellulose prepared in our laboratory by treatment with concentrated sulfuric acid. When hydrolyzed with cellulase, NCC produces significant amount of cello‐oligosaccharides (COS) as reaction intermediates along with glucose and cellobiose. The COS produced by cellulase were categorized into two different moieties based upon their degree of polymerization (DP): low DP (less than 7) COS (LD‐COS) and high DP COS (HD‐COS). Endo‐glucanase (Endo‐G) reacts rapidly on the NCC reducing its DP to 30–60, after which the Endo‐G reaction with NCC ceases. HD‐COS is produced from NCC by the action of Endo‐G, whereas LD‐COS is produced by exo‐glucanase (Exo‐G). β‐Glucosidase (β‐G) hydrolyzes LD‐COS to produce cellobiose, but it does not hydrolyze HD‐COS. DP of NCC affects the action of Exo‐G in such a way that the overall yield is high for high DP NCC. This is in line with previous findings that substrate‐recognition by Exo‐G requires binding on β‐glucan chain with DP of 10 for the hydrolysis to take place. The individual cellulose chain residues within solid having DP less than 10 therefore remain unreacted. The percentage of the unreacted portion would be lower for high DP NCC, which results high overall conversion. The surface area and the number of reactive sites on the substrate facilitate adsorption of enzyme therefore the initial rate of the hydrolysis. The overall extent of conversion of cellulose, however, is controlled primarily by its inherent characteristics such as DP and crystallinity. Biotechnol. Bioeng. 2009;102: 1570–1581. © 2008 Wiley Periodicals, Inc.     

Selective inhibition of dipeptidyl peptidase 4 by targeting a substrate-specific secondary binding site

Dipeptidyl peptidase 4/CD26 (DP4) is a multifunctional serine protease liberating dipeptide from the N-terminus of (oligo)peptides which can modulate the activity of these peptides. The enzyme is involved in physiological processes such as blood glucose homeostasis and immune response. DP4 substrate specificity is characterized in detail using synthetic dipeptide derivatives. The specificity constant k(cat)/K(m) strongly depends on the amino acid in P?-position for proline, alanine, glycine and serine with 5.0 x 10? M?1 s?1, 1.8 x 10? M?1 s?1, 3.6 x 102 M?1 s?1, 1.1 x 102 M?1 s?1, respectively. By contrast, kinetic investigation of larger peptide substrates yields a different pattern. The specific activity of DP4 for neuropeptide Y (NPY) cleavage comprising a proline in P?-position is the same range as the k(cat)/K(m) values of NPY derivatives containing alanine or serine in P?-position with 4 x 10? M?1 s?1, 9.5 x 10? M?1 s?1 and 2.1 x 10? M?1 s?1, respectively. The proposed existence of an additional binding region outside the catalytic center is supported by measurements of peptide substrates with extended chain length. This 'secondary' binding site interaction depends on the amino acid sequence in P?'-P?'-position. Interactions with this binding site could be specifically blocked for substrates of the GRF/glucagon peptide family. By contrast, substrates not belonging to this peptide family and dipeptide derivative substrates that only bind to the catalytic center of DP4 were not inhibited. This more selective inhibition approach allows, for the first time, to distinguish between substrate families by substrate-discriminating inhibitors.     

Night work as a risk factor for future cause-specific disability pension: A prospective twin cohort study in Sweden

The objectives of the study were to investigate the associations between night work and disability pension (DP) due to all causes, cardiovascular (CVD), mental, and other diagnoses, adjusting for familial confounding. The material of the study included comprehensive survey data on 27 165 Swedish twins born in 1935–1958 that were linked with DP data for the survey period (1998–2003) to 2013. Night work was assessed as years of working nights at least every now and then, and categorized into not at all, 1–10 years and over 10 years. For statistical analyses, Cox proportional hazards regressions were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). The results of the study indicated that over 10 years duration of night work had an age- and sex-adjusted HR of 1.48 (95% CI 1.11–1.98) for DP due to CVD and 1–10 years of night work an HR of 1.28 (95% CI 1.06–1.55) for DP due to mental diagnoses, but attenuated when covariates were adjusted for. Both 1–10 years (HR 1.27, 95% CI 1.17–1.39) and >10 years of night work (HR 1.20, 95% CI 1.08–1.34) were associated with DP due to all causes and other diagnoses. These risks remained after adjusting for covariates. To conclude, even modest exposure in terms of duration of night work is a risk factor for all-cause DP, but also for DP due to mental and other diagnoses. The risk of DP due to CVD seems to be associated with longer (>10 years) periods of night work. All the associations between night work and DP seem to be influenced by various covariates.     

Regioselectivity of enzymatic modification of poly(methyl acrylate)

Enzymes are potentially useful catalysts for polymerization as well as modification of polymers. While lipases have been used previously for polymerization reactions, they have not been used for modification of polymers. In this report, lipases were used to determine regioselective modification of ester functions in a telomer of poly(methyl acrylate). The influence of chain length on the extent of transesterification of methyl acrylate telomers of DP(n) 6-50 was studied by examining the relationship between the extents of enzymic modification to other telomerization parameters. The regioselectivity was observed when the average DP(n) of telomers is in a range of 6-22. At a higher DP(n) (>22), however, the average number of reacting ester functions per telomer strongly deviated from the theoretically predicted value. This phenomenon was suspected as a result of steric hindrance caused by folding of longer telomer chains. To verify this hypothesis, acrylate telomers at a DP(n) ranging from 10 to 42 were synthesized using a shorter telogen, i.e., 2,2'-ethanedithiol. The transesterification of these telomers showed a deviation in a degree of conversion when DP(n) was greater than 10, possibly indicating the inhibition caused by steric hindrance. Therefore, regioselective modification of acrylic polymers, which is difficult to achieve by conventional chemical methods, may be accomplished enzymatically.     

Molecular configuration of amylose and its complexes in aqueous solutions. Part II. Relation between the DP of helical segments of the amylose–iodine complex and the equilibrium concentration of free iodine

The iodine which is added to an aqueous amylose solution is bound only partly by the amylose while forming the blue complex and partly remains free. The equilibrium normality of the free and the bound iodine at half-saturation of amylose by iodine is designated as [I_f]_v and [I_b]_w, respectively. The stability of the poly iodine chain formed within the axis of amylose helices depends on its length, i.e., indirectly on the DP of the amylose helices: the greater this stability, the lower the [I_f]_v value. The amylose molecule consists of helical segments. Such a molecule may behave as a random coil. The average length of the helical segments in freshly prepared amylose-iodine complexes depends on temperature, pH, iodide concentration, the presence of other complex-forming agents, and the DP of the amylose. This latter factor is investigated in the present paper. By the aid of an automatically recording photometrictitrating device the coherent values of [I_b] and [I_f] were determined. Plotting these values against DP _n for mechanochemically degraded as well as for periodateo-xidized amyloses resulted in curves consisting of two linear sections. The break of the curves occurred between DP _n 110 and 130. It was concluded that below DP _n = 100 the DP of helical segments (= sDP _n) is identical to the DP _n of the total molecule, i.e., the molecule consists of only a single, relatively stiff helix. Above this limit the molecule contains several helical segments. The DP of these helical segments can be calculated as follows: sDP _n = 141.1 ? 10.2 × 10⁵[I_f]_v. This equation is considered to be valid for 0.5–0.6 mg. amylose in 100 ml. 0.1N HCl at 20°C., λ = 650 mμ, euuvet diameter 3.4 cm., the feed rate of the iodate-iodide titrating solution (in acid medium resulting in a 5 × 10^?3N I₂ solution with a molar iodide to iodine ratio of 1.5) is 0.4ml./min. Amylose molecules of, e.g., DP ⁿ = 1380 consist of an average of 11.4 segments having a DP of about 120 and consisting of an average of 15–18 helical turns.     

Synthesis of highly ordered cellulose II in vitro using cellodextrin phosphorylase

Synthesis of cellulose in vitro is expected to afford tailor-made cellulosic materials with highly homogeneous structure compared to natural cellulosic materials. Here we report the enzymatic synthesis of cellulose II with high crystallinity from glucose and α-glucose 1-phosphate (αG1P) by cellodextrin phosphorylase (CDP). Although glucose had been believed not to act as a glucosyl acceptor of CDP, a significant amount of insoluble cellulose was precipitated without accumulation of soluble cello oligosaccharides when glucose was mixed with αG1P and CDP. This phenomenon can be explained in terms of the large difference in acceptor reactivity between glucose and cello oligosaccharides. ¹H NMR spectrometric analysis revealed that this insoluble cellulose had an average degree of polymerization (DP) of nine. TEM observation, together with electron and X-ray diffraction studies, indicated that the insoluble cellulose formed platelet-shaped single lamellar crystals of cellulose II, several μm in length and several hundred nm in width; this is large compared to reported cellulose crystals. The thickness of the lamellar crystal is 4.5 nm, which is equivalent to a chain length of a cello oligosaccharide with DP nine and is consistent with the ¹H NMR spectroscopic results. These results suggest that cello oligosaccharides having an average DP of nine are synthesized in vitro by CDP when glucose is used as an acceptor, and the product forms highly crystalline cellulose II when it precipitates.     

The effects of load and training pattern on acute neuromuscular responses in the upper body

The purpose of this study was to examine the effects of repetition maximum (RM) loads and training patterns on acute neuromuscular responses in the upper body. Markers of fatigue were monitored under a descending pattern (DP), in which repetitions decreased in subsequent sets, and an ascending pattern (AP), in which repetitions increased in subsequent sets. Both training patterns were performed using 5- and 10-RM loads. Fatigue was assessed by monitoring changes in force output, motor unit activation and muscle twitch characteristics (peak twitch [PT], time to PT [TPT], and ? relaxation time [RT]). All 4 protocols (5-RM DP, 5-RM AP, 10-RM DP, and 10-RM AP) produced significant decreases pre to postprotocol in force output, TPT, and ?RT. With the exception of 5-RM DP, all protocols produced significant decreases in motor unit activation. Pre to postprotocol, PT forces were potentiated under 5-RM loads, whereas they were depressed under 10-RM loads. Hence, a main effect for training protocols showed that changes in PT force were significantly different under 5-RM, as compared to 10-RM loads. The results indicate that central fatigue may be independent of load and pattern, whereas peripheral fatigue would appear to be dependent on load but not pattern.     

Potato phosphorylase catalyzed synthesis of amylose-lipid complexes

On-line size-exclusion chromatography monitoring of potato phosphorylase catalyzed amylose synthesis--starting from alpha-D-glucose-1-P and maltohexaose--revealed rather monodisperse amylose populations. In the presence of lipids, amylose-lipid complexes spontaneously formed and precipitated. They were recovered by centrifugation, freeze-dried, and characterized by wide-angle X-ray diffraction and differential scanning calorimetry. The presence of lipids during amylose synthesis led to lower amylose degrees of polymerization (DP). Lipid chain length defined amylose DP, which increased in the order myristic acid (C14), glyceryl monostearate (GMS), stearic acid (C18), and docosanoic acid (C22). The thermal stability of the complexes increased in the same manner, with the C22 complexes having the highest dissociation temperature. In addition, we hypothesized that these results provide additional evidence for the fringed micellar organization of (semi-enzymically synthesized) amylose-lipid complexes.     

Ultrasonic wave spectroscopy study of sugar oligomers and polysaccharides in aqueous solutions: the hydration length concept

The determination of apparent persistence length and radius of gyration of maltodextrins in water is achievable through high-resolution ultrasonic spectroscopy measurements. Classical hydration number for those carbohydrates is characteristic of an apparent persistence degree of polymerisation of the polymer. A force-field based molecular modeling of a 10DP malto-oligomer allows measurement of the corresponding length for the lowest energetic conformation in solution. A good agreement between the apparent radii of gyration determined by this technique and the freely rotating polymer chain model is found with radii of gyration calculated from the intrinsic viscosity.     

Glycosaminoglycan destabilization of DNA-chitosan polyplexes for gene delivery depends on chitosan chain length and GAG properties

Chitosan-based gene delivery systems are promising candidates for non-viral gene therapy. A wide range of chitosans has been studied to optimize the properties of the DNA-chitosan complexes to yield high transfection efficiencies. An important parameter to control is the polyplex stability to allow transport towards the cells, subsequent internalization and release of DNA intracellularly. The stability of the DNA-chitosan complexes was here studied after exposure to heparin and hyaluronic acid (HA) using atomic force microscopy (AFM) and ethidium bromide (EtBr) fluorescence assay. To study the effect of polycation chain length on the polyplex stability, chitosans with a degree of polymerization (DP) varying from approximately 10 to approximately 1000 were employed for DNA compaction. Whereas HA was unable to dissociate the complexes, the degree of dissociation caused by heparin depended on both the chitosan chain length and the amount of chitosan used for complexation. When increasing the chitosan concentration, larger heparin concentrations were required for polyplex dissociation. Furthermore, increasing the chitosan chain length yielded more stable complexes. Varying the chitosan chain length thus provides a tool for controlling the ability of the polyplex to deliver therapeutic gene vectors to cells.     

Dynamics of myosin heavy chain isoform transition in the longissimus muscle of domestic and wild pigs during growth: a comparative study

Dynamics of myofiber differentiation/maturation in porcine skeletal muscle is associated with domestication, breeding and rearing conditions. This study was aimed to comparatively elucidate the age-dependent myosin heavy chain (MyHC) isoform expression and transition pattern in domestic and wild pig (WP) skeletal muscle from birth until adulthood. Domestic pigs (DPs) of Large White breed raised in conventional production system were compared with WPs reared in a large hunting enclosure. Muscle samples for immuno/enzyme histochemistry were taken from the longissimus dorsi muscle within 24 h postmortem at 24 to 48 h, 21 to 23 days, 7 months and ~2 years postpartum. Based on the antibody reactivity to MyHCs (NCL-MHCs, A4.74, BF-F3) and succinate dehydrogenase activity, myofibers were classified into I, I/IIa, IIa, IIx and IIb types. In addition, foetal MyHC expression was determined with the use of F158.4C10 antibody. Maturation of the longissimus dorsi muscle in the WP was characterized by an accelerated transformation of the fast to slow MyHC during the first hours postpartum, followed by differentiation towards oxidative myofibers in which type I, IIa and IIx MyHCs predominated. In the DP, the transformation shifted towards glycolytic myofibers that expressed MyHC-IIb. The expression of foetal MyHC was higher in the DP than in the WP at 1 day of age, and the decline in the foetal MyHC during the first 3 weeks was more rapid in the WP than in the DP denoting an accelerated early postnatal muscle maturation in WP than DP piglets. All foetal MyHC-positive myofibers co-expressed IIa isoform, but not vice versa. The intense myofiber hypertrophy was evident from 3 weeks until 7 months of age. In this period, the myofiber cross-sectional area increased up to 10- and 20-fold in the WP and the DP, respectively. In the DP, the hypertrophy of all myofiber types was more pronounced than in the WP, particularly the hypertrophy of IIx and IIb myofibers. To summarize, the comparison between growing DP with wild ancestors showed that genetic selection and rearing conditions lead to substantial changes in the direction and intensity of postnatal MyHC transformation as evidenced by different proportion of individual myofiber types and differences in their hypertrophic potential.     

Oligosaccharide Substrate Preferences of Human Extracellular Sulfatase Sulf2 Using Liquid Chromatography-Mass Spectrometry Based Glycomics Approaches

Sulfs are extracellular endosulfatases that selectively remove the 6-O-sulfate groups from cell surface heparan sulfate (HS) chain. By altering the sulfation at these particular sites, Sulfs function to remodel HS chains. As a result of the remodeling activity, HSulf2 regulates a multitude of cell-signaling events that depend on interactions between proteins and HS. Previous efforts to characterize the substrate specificity of human Sulfs (HSulfs) focused on the analysis of HS disaccharides and synthetic repeating units. In this study, we characterized the substrate preferences of human HSulf2 using HS oligosaccharides with various lengths and sulfation degrees from several naturally occurring HS sources by applying liquid chromatography mass spectrometry based glycomics methods. The results showed that HSulf2 preferentially digests highly sulfated HS oligosaccharides with zero acetyl groups and this preference is length dependent. In terms of length of oligosaccharides, HSulf2 digestion induced more sulfation decrease on DP6 (DP: degree of polymerization) compared to DP2, DP4 and DP8. In addition, the HSulf2 preferentially digests the oligosaccharide domain located at the non-reducing end (NRE) of the HS and heparin chain. In addition, the HSulf2 digestion products were altered only for specific isomers. HSulf2 treated NRE oligosaccharides also showed greater decrease in cell proliferation than those from internal domains of the HS chain. After further chromatographic separation, we identified the three most preferred unsaturated hexasaccharide for HSulf2.     

Preparation of low-molecular-weight chitosan using phosphoric acid

Two types of low degree of polymerisation (DP) chitosan were prepared by homogeneous hydrolysis of chitosan in 85% phosphoric acid at room temperature for 1–6 weeks. The hydrolysates were collected by addition of excess ethanol, and were fractionated by solubility in water. The changes in yields of water-insoluble (higher DP) and water-soluble (lower DP) fractions were determined as a function of hydrolysis time. The hydrolysis proceeded with further deacetylation of chitosan, resulting in degree of deacetylation of more than 90%. The water-insoluble fraction prepared after the hydrolysis for 4 weeks (43% yield) had a weight-average DP ( ) of 16·8, and showed the ‘tendon’ type X-ray diffraction pattern. The water-soluble fraction (12·5% yield) had a of 7·3, and showed the ‘annealed’ type pattern.     

Desmoplakin I and desmoplakin II. Purification and characterization

Desmoplakins I and II (DP1 and DP2), major cytoskeletal structural proteins concentrated in desmosomes, have been purified in milligram quantities from keratomed pig tongue epithelium. DP1 and DP2 extracted from purified desmosomes in 4 M urea were chromatographed on DEAE-cellulose and remained soluble after removal of urea during subsequent chromatography. The two proteins differed by only about 15% in molecular weight (Mr = 285,000 for DP1 and 225,000 for DP2 on sodium dodecyl sulfate-polyacrylamide gels) were found to have similar Svedberg constants, 6.7 S (DP1) and 6.4 S (DP2); nevertheless, separation was readily achieved by gel filtration, since DP1 has a Stokes radius (Rs) of 164 nm, but DP2 has a Rs = 90 nm. Calculated molecular mass was 462,000 daltons for DP1 and 242,000 daltons for DP2, suggesting that DP1 may be a dimer in solution and DP2 a monomer. Cross-linking by disuccinimidyl suberate of 125I-labeled DP1 or DP2 at nanomolar concentrations confirmed that DP1 is a dimer by doubling of its apparent Mr on sodium dodecyl sulfate gels and indicated that DP2, which failed to become cross-linked, is a monomer. DP1 in the presence of 8 M urea could not be cross-linked, indicating that urea dissociated the dimers. Calculated frictional ratios (f/f0 = 3 for DP1 and 2 for DP2) indicate that both proteins are highly asymmetric. Rotary shadowing of DP1 demonstrated flexible dumbbell-like extended shapes with a maximal length of about 180 nm with a central rod and coiled or folded end domains. DP2 showed variable extended shapes of maximal length of 78-93 nm. The increased length and Rs of desmoplakin I is probably accounted for by formation of tail-to-tail dimers. Two-dimensional peptide maps and amino acid analysis showed very similar profiles for the two proteins. Purified keratin filaments failed to bind DP1 or DP2, and prekeratins polymerized in vitro and sedimented failed to remove desmoplakins, suggesting that desmoplakins do not bind keratins directly. These studies provide a basis for functional and detailed structural studies with purified native desmosomal proteins.     

Three Native Cellulose-Depolymerizing Endoglucanases from Solid-Substrate Cultures of the Brown Rot Fungus Meruliporia (Serpula) incrassata

Three extracellular cellulose-depolymerizing enzymes from cotton undergoing decay by the brown rot fungus Meruliporia (Serpula) incrassata were isolated by anion-exchange and hydrophobic interaction chromatographies. Depolymerization was detected by analyzing the changes in the molecular size distribution of cotton cellulose by high-performance size-exclusion chromatography. The average degree of polymerization (DP; number of glucosyl residues per cellulose chain) was calculated from the size-exclusion chromatography data. The very acidic purified endoglucanases, Cel 25, Cel 49, and Cel 57, were glycosylated and had molecular weights of 25,200, 48,500, and 57,100, respectively. Two, Cel 25 and Cel 49, depolymerized cotton cellulose and were also very active on carboxymethyl cellulose (CMC). Cel 57, by contrast, significantly depolymerized cotton cellulose but did not release reducing sugars from CMC and only very slightly reduced the viscosity of CMC solutions. Molecular size distributions of cotton cellulose attacked by the three endoglucanases revealed single major peaks that shifted to lower DP positions. A second smaller peak (DP, 10 to 20) was also observed in the size-exclusion chromatograms of cotton attacked by Cel 49 and Cel 57. Under the reaction conditions used, Cel 25, the most active of the cellulases, reduced the weight average DP from 3,438 to 315, solubilizing approximately 20% of the cellulose. The weight average DP values of cotton attacked under the same conditions by Cel 49 and Cel 57 were 814 and 534; weight losses were 9 and 11% respectively.