Varying Amounts Of Protein Research Articles

Cytochemistry of pollen development in Campsis radicans (L.) Seem. (Bignoniaceae)

In this study, cytochemical staining methods were used to follow the cytochemical modifications of microspore cytoplasm and sporoderm in Campsis radicans (L.) Seem. from tetrad stage to mature pollen. Flower buds were collected at different stages of development, and the anthers were fixed and embedded in Araldite. To make cytochemical observations under light microscope, semithin sections were cut and stained with different dyes. Cytochemical methods provided the opportunity to localize the reserve material in the microspore and pollen cytoplasm, to distinguish the different layers of the sporoderm, and to determine its chemical structure at different developmental stages. Microspore cytoplasm contains variable amounts of proteins, lipids, and insoluble carbohydrates at different stages of microsporogenesis. Sporoderm formation starts at tetrad stage by the formation of primexine and is completed at vacuolated microspore stage by the addition of sporopollenin from tapetum. During the vacuolization and enlargement of the microspores, the structure and the chemical composition of the exine are modified. The endexine becomes chemically different from the ectexine. The ectexine is composed of sporopollenin and a small amount of protein, whereas the endexine is composed of sporopollenin, proteins, and traces of polysaccharides.

Characterization and immunomodulatory activities of sulfated polysaccharides from Capsosiphon fulvescens

Sulfated polysaccharides isolated from Capsosiphon fulvescens and fractionated using ion-exchange chromatography were investigated to determine their chemical and molecular characteristics and biological activities. The crude and fractionated polysaccharides (F1, F2, and F3) consisted mostly of carbohydrates (28.9–67.0%), uronic acids (1.6–9.2%) and sulfates (5.2–13.4%) with various amounts of proteins (2.1–53.7%). Their monosaccharide levels were significantly different including rhamnose (20.8–65.2%), xylose (13.0–37.1%) and mannose (11.6–65.1%). The polysaccharides contained one or two subfractions with molecular weights (Mw) ranging from 401.7×103 to 6232×103g/mol. These polysaccharides (the crude and fraction F2) strongly stimulated macrophage cells, RAW264.7 cell line, producing considerable amounts of NO, PGE2 and cytokines which suggested that they could be strong immunostimulators. The main backbone of the most immunoenhancing polysaccharide (F2) was suggested by GC–MS and NMR to be the following: [Display omitted]

Molecular properties of water-unextractable proteoglycans from Hypsizygus marmoreus and their in vitro immunomodulatory activities.

Four proteoglycans were sequentially extracted from Hypsizygus marmoreus using 0.1 M NaOH (alkali-soluble proteoglycans [F1] and alkali-insoluble proteoglycans [F3]) and 0.1 M HCl (acid-soluble proteoglycans [F2] and acid-insoluble proteoglycans [F4]), and their structures and immunomodulatory activities were investigated. The proteoglycans were found to contain carbohydrates (19.8–82.4%) with various amounts of proteins (7.7–67.3%), and glucose was the major monosaccharide unit present, along with trace amounts of galactose. The molecular weights (Mw) and the radius of gyration (Rg) of these proteoglycans showed ranges of 16 × 104–19,545 × 104 g/mol and 35–148 nm, respectively, showing significant variations in their molecular conformations. The backbones of F1 and F2 were mainly connected through α-(1®3), (1®4) and b-(1®6)-glycosidic linkages with some branches. The F1 and F2 proteoglycans significantly stimulated Raw264.7 cells to release nitric oxide (NO), prostaglandin E2 (PGE2) and various cytokines, such as IL-1β, TNF-α and IL-6 by inducing their mRNA expressions.

Changes in dietary protein intake has no effect on serum cystatin C levels independent of the glomerular filtration rate

Cystatin C is being considered as a replacement for serum creatinine in the estimation of the glomerular filtration rate (GFR); however, its plasma levels might be affected by factors other than the GFR, such as protein intake. We performed a post hoc analysis of the data in the Modification of Diet in Renal Disease study, in which we compared serum creatinine and cystatin C levels in 741 patients with available estimates of protein intake at baseline prior to their randomization to diets containing various amounts of protein, and at 2 years of follow-up in 426 of these patients in whom a cystatin C measurement was available. The 503 patients in study A (GFR 25-55 ml/min per 1.73 m(2)) had been assigned a low (0.58 g/kg per day) or a usual (1.3 g/kg per day) protein intake, and the 238 participants in study B (GFR 13-24 ml/min per 1.73 m(2)) were assigned a very low (0.28 g/kg per day) or the low protein intake. In either study group, lowering the dietary protein intake reduced the change in creatinine, but did not have a significant change in cystatin C. Thus, in patients with moderate-to-severe chronic kidney disease, serum cystatin C unlike serum creatinine was not affected by dietary protein intake independent of changes in GFR. Hence, cystatin C may allow more accurate estimates of GFR than creatinine for patients with reduced protein intake. Further study of other non-GFR determinants of cystatin C is needed before the widespread adoption.

Microchip-Based Nano Chromatography and Nano Capillary Electrophoresis in Genomics and Proteomics

The growing interest in proteomics and genomics needs analytical techniques capable of detecting proteins and nucleic acids at the ng L−1 levels due to the small amounts of various proteins and nucleic acids in living cells. During the last decade remarkable development has occurred in the evolution of chromatographic and capillary electrophotetic methods on microchips. These methods are called nano liquid chromatography (NLC) and nano capillary electrophoresis (NCE). The present review article describes the application of NLC and NCE to proteomics and genomics research The analyses of proteins and nucleic acids at low levels is described together with the optimization and future trends of nano methods in genomics and proteomics.

Modifications of the Lipoamide-containing Mitochondrial Subproteome in a Yeast Mutant Defective in Cysteine Desulfurase

Comparison and identification of mitochondrial matrix proteins from wild-type and cysteine desulfurase-defective (nfs1-14, carrying a hypomorphic allele of NFS1) yeast strains, using two-dimensional gel electrophoresis coupled to mass spectrometry analyses, revealed large changes in the amounts of various proteins. Protein spots that were specifically increased in the nfs1-14 mutant included subunits of lipoamide-containing enzyme complexes: Kgd2, Lat1, and Gcv3, subunits of the mitochondrial alpha-ketoglutarate dehydrogenase, pyruvate dehydrogenase, and glycine cleavage system complexes, respectively. Moreover the increased protein spots corresponded to lipoamide-deficient forms in the nfs1-14 mutant. The increased proteins migrated as separate, cathode-shifted spots, consistent with gain of a lysine charge due to lack of lipoamide addition. Lack of lipoylation of these proteins was further validated using an antibody specific for lipoamide-containing proteins. In addition, this antibody revealed a fourth lipoamide-containing protein, probably corresponding to the E2 component of the branched-chain keto acid dehydrogenase complex. Like the lipoamide-containing forms of Kgd2, Lat1, and Gcv3, this protein also showed decreased lipoic acid reactivity in the nfs1-14 mutant. Cysteine desulfurases, such as yeast NFS1, are required for sulfur addition to iron-sulfur clusters and other sulfur-requiring processes. The results demonstrate that Nfs1 protein is required for the proper post-translational modification of the lipoamide-containing mitochondrial subproteome in yeast and pave the road toward a thorough understanding of its precise role in lipoic acid synthesis.

Skp2 Contains a Novel Cyclin A Binding Domain That Directly Protects Cyclin A from Inhibition by p27Kip1

Skp2 is well known as the F-box protein of the SCF(Skp2) x Roc1 complex targeting p27 for ubiquitylation. Skp2 also forms complexes with cyclin A, which is particularly abundant in cancer cells due to frequent Skp2 overexpression, but the mechanism and significance of this interaction remain unknown. Here, we report that Skp2-cyclin A interaction is mediated by novel interaction sequences on both Skp2 and cyclin A, distinguishing it from the well known RXL-hydrophobic patch interaction between cyclins and cyclin-binding proteins. Furthermore, a short peptide derived from the mapped cyclin A binding sequences of Skp2 can block Skp2-cyclin A interaction but not p27-cyclin A interaction, whereas a previously identified RXL peptide can block p27-cyclin A interaction but not Skp2-cyclin A interaction. Functionally, Skp2-cyclin A interaction is separable from Skp2 ability to mediate p27 ubiquitylation. Rather, Skp2-cyclin A interaction serves to directly protect cyclin A-Cdk2 from inhibition by p27 through competitive binding. Finally, we show that disruption of cyclin A binding with point mutations in the cyclin A binding domain of Skp2 compromises the ability of overexpressed Skp2 to counter cell cycle arrest by a p53/p21-mediated cell cycle checkpoint without affecting its ability to cause degradation of cellular p27 and p21. These findings reveal a new functional mechanism of Skp2 and a new regulatory mechanism of cyclin A.

Label-Free Protein Quantification Using LC-Coupled Ion Trap or FT Mass Spectrometry: Reproducibility, Linearity, and Application with Complex Proteomes

A critical step in protein biomarker discovery is the ability to contrast proteomes, a process referred generally as quantitative proteomics. While stable-isotope labeling (e.g., ICAT, 18O- or 15N-labeling, or AQUA) remains the core technology used in mass spectrometry-based proteomic quantification, increasing efforts have been directed to the label-free approach that relies on direct comparison of peptide peak areas between LC-MS runs. This latter approach is attractive to investigators for its simplicity as well as cost effectiveness. In the present study, the reproducibility and linearity of using a label-free approach to highly complex proteomes were evaluated. Various amounts of proteins from different proteomes were subjected to repeated LC-MS analyses using an ion trap or Fourier transform mass spectrometer. Highly reproducible data were obtained between replicated runs, as evidenced by nearly ideal Pearson's correlation coefficients (for ion's peak areas or retention time) and average peak area ratios. In general, more than 50% and nearly 90% of the peptide ion ratios deviated less than 10% and 20%, respectively, from the average in duplicate runs. In addition, the multiplicity ratios of the amounts of proteins used correlated nicely with the observed averaged ratios of peak areas calculated from detected peptides. Furthermore, the removal of abundant proteins from the samples led to an improvement in reproducibility and linearity. A computer program has been written to automate the processing of data sets from experiments with groups of multiple samples for statistical analysis. Algorithms for outlier-resistant mean estimation and for adjusting statistical significance threshold in multiplicity of testing were incorporated to minimize the rate of false positives. The program was applied to quantify changes in proteomes of parental and p53-deficient HCT-116 human cells and found to yield reproducible results. Overall, this study demonstrates an alternative approach that allows global quantification of differentially expressed proteins in complex proteomes. The utility of this method to biomarker discovery is likely to synergize with future improvements in the detecting sensitivity of mass spectrometers.

Meta‐regression analysis of low carbohydrate variable protein energy‐restricted diet studies on weight loss and body composition in humans

Low-carbohydrate diets have been popular and contain less carbohydrate (C) than the recommended range of 45–60% of energy as well as variable amounts of protein (P). Studies reporting effects of such diets on degree of weight loss and composition are equivocal, and may relate to differences in study size and design. Therefore, a meta-regression was used to determine the effects of variations in C and P intake on body mass and composition during energy restriction. A total of 87 studies comprising 165 intervention groups met our inclusion criteria: English-language studies with subjects 19 y and consuming diets 4200 kJ/d (1000 kcal/d) for 4 wks, and evidence of a biological marker of macronutrient intake in conjunction with self-report. Results showed that, when controlling for energy intake, diets of up to 41% C energy led to greater losses of weight by 1.7 kg, of fat-free mass by 0.7 kg, of fat mass by 2.0 kg, and of body fat by 1.3% compared with higher C diets. In studies > 12 wks, these differences increased to 6.6 kg, 1.7 kg, 5.6 kg, and 3.6%, respectively. On diets where P intakes were > 1.05 g/kg, fat-free mass retention was 0.6 kg more vs. lower P intakes, and in studies > 12 wks, this retention doubled. There was no relation of P intake level to average loss of weight or fat-mass. It appears that low-C, high-P diets favorably affect body weight and composition independent of energy intake, supporting the likelihood of a metabolic advantage to these diets. Supported in part by FLA-FOS-03972.

Reverse Gyrase, the Two Domains Intimately Cooperate to Promote Positive Supercoiling

Reverse gyrases are atypical topoisomerases present in hyperthermophiles and are able to positively supercoil a circular DNA. Despite a number of studies, the mechanism by which they perform this peculiar activity is still unclear. Sequence data suggested that reverse gyrases are composed of two putative domains, a helicase-like and a topoisomerase I, usually in a single polypeptide. Based on these predictions, we have separately expressed the putative domains and the full-length polypeptide of Sulfolobus acidocaldarius reverse gyrase as recombinant proteins in Escherichia coli. We show the following. (i) The full-length recombinant enzyme sustains ATP-dependent positive supercoiling as efficiently as the wild type reverse gyrase. (ii) The topoisomerase domain exhibits a DNA relaxation activity by itself, although relatively low. (iii) We failed to detect helicase activity for both the N-terminal domain and the full-length reverse gyrase. (iv) Simple mixing of the two domains reconstitutes positive supercoiling activity at 75 degrees C. The cooperation between the domains seems specific, as the topoisomerase domain cannot be replaced by another thermophilic topoisomerase I, and the helicase-like cannot be replaced by a true helicase. (v) The helicase-like domain is not capable of promoting stoichiometric DNA unwinding by itself; like the supercoiling activity, unwinding requires the cooperation of both domains, either separately expressed or in a single polypeptide. However, unwinding occurs in the absence of ATP and DNA cleavage, indicating a structural effect upon binding to DNA. These results suggest that the N-terminal domain does not directly unwind DNA but acts more likely by driving ATP-dependent conformational changes within the whole enzyme, reminiscent of a protein motor.

Collagen Immobilization onto P(EGDMA/HEMA) Microbeads for Cell Affinity Systems

Both nonswellable and swellable poly(EGDMA/HEMA) microbeads were produced by suspension copolymerization. These microbeads were modified by immobilization of a spacer-arm (hexamethylene diamine, HMDA) and collagen. The optimal values for modifications were as follows: sodium periodate concentration: 0.467 × 10-2 mmol/mL; HMDA concentration: 3.5 × 10-2 mmol/mL; and glutaraldehyde concentration: 0.70 × 106 mmol/mL. Adsorption of collagen onto plain and periodate oxidized poly(EGDMA/HEMA) microbeads were similar, 0.25 and 0.50 mg collagen/g polymer, respectively. Collagen immobilization on poly(EGDMA/HEMA) microbeads was studied at various temperatures, times, and pH by using protein solution containing various amounts of proteins. The optimal values for immobilizations were as follows: the initial collagen concentration: 0.25 mg/mL; temperature: 4°C; pH 7; and the immobilization time; 120 min. Both fibroblastic 3T3 and epithelial MDBK cells were attached to these unmodified and modified microbeads. The attachments of 3T3 and MDBK cells, especially to the collagen immobilized swellable microbeads were very high. Almost 96% of the 3T3 cells available in the cell culture medium became attached to these microbeads (2297 ± 122 cells per mg of polymer). There was no significant effect by swelling on cell attachment.

Protein profiling in cardiac tissue in response to the chronic effects of alcohol.

An investigation was made into cardiac protein levels after chronic ethanol consumption to examine whether specific proteins are affected by alcohol. Ethanol was administered for six weeks to male Wistar rats which were fed a nutritionally complete liquid diet containing 35% of total calories as ethanol. Controls were pair-fed identical amounts of the same diet in which ethanol was replaced by isocaloric glucose; thus both groups had identical nutritional intakes, albeit differences in ethanol or carbohydrate. After six weeks' feeding, cardiac tissue was removed and analyzed by two-dimensional electrophoresis, where equal amounts of proteins were studied. Protein patterns were analyzed by computerized densitometry and characterized by comparison with a database of known cardiac proteins. Chronic alcohol feeding caused significant decreases in the relative amounts of various proteins, including several tentatively identified as heat shock protein (HSP) 60, HSP70, and desmin. The relative proportions of actin, vimentin, myosin light chain 1, myosin light chain 2, and albumin, remained unchanged. Examination of antibodies raised against HSP65 showed no overt differences in plasma levels following chronic alcohol consumption, and liver changes as assessed by histology were mild. In conclusion, chronic alcohol appears to have selective effects on particular proteins, and the effects were not directly ascribed to overt liver dysfunction or malnutrition. This may explain some of the functional and morphological characteristics observed in alcohol-induced heart muscle disease, including reduced contractility.

Heat-Induced Modifications in the Association of Specific Proteins with the Nuclear Matrix

Nuclei isolated from heat-shocked mammalian cells have an increased protein content which reflects an enhanced protein binding to nuclear structures. These nuclear changes are correlated with cell survival and inhibition of DNA replication, transcription and repair of DNA damage. It appears that most of the altered protein binding occurs in association with the nuclear matrix. The present study was conducted to determine if measurements of specific proteins in isolated nuclei reflect changes that occur at the nuclear matrix. The amounts of various proteins associated with HeLa cell nuclei and nuclear matrices after heat shock were measured by (1) densitometric scans of Coomassie blue-stained gels, (2) immunoblotting with antibodies to nuclear proteins and (3) antisera raised against nuclear matrix proteins from heated cells. These measurements revealed heat-induced increases in the levels of many nuclear matrix proteins. While a number of proteins show similar changes in both nuclei and nuclear matrices, for many the extent of increased association with the nuclear matrix is not reflected in the measured changes in the nuclei. These results are essential for understanding and studying further the relationships between the cellular response to hyperthermia and heat-altered associations of specific proteins with either nuclei or nuclear matrices.

Estimation of the renal net acid excretion by adults consuming diets containing variable amounts of protein

The object of this study was to determine whether it is possible to reliably estimate the renal net acid excretion (NAE) produced by adults consuming different amounts of dietary protein. A physiologically based calculation model that corrects for intestinal absorption of minerals and sulfur-containing protein and assumes a rate of urinary excretion of organic acids proportional to body surface area was used to estimate NAE. Urinary excretion of different minerals and NAE was measured during the last 48 h of each of four separate 5-d diet periods in six healthy adults. On the basis of food tables, the four nearly isoenergetic diets (one lacto-vegetarian and one high- and two moderate-protein diets) were estimated to yield the following NAE values: 3.7, 117.5, 62.2, and 102.2 mEq/d, respectively. The analytically determined urinary NAE (24.1 +/- 10.7, 135.5 +/- 16.4, 69.7 +/- 21.4, and 112.6 +/- 10.9 mEq/d) corresponded reasonably well to these estimates, suggesting that the calculation model is appropriate to predict the renal NAE from nutrient intake and anthropometric data.

Standard experimental diets for crustacean nutrition research. II. Growth and survival of juvenile crayfish Astacus astacus (Linné) fed diets containing various amounts of protein, carbohydrate and lipid

Nutritional experiments were conducted with individual juvenile freshwater crayfish, Astacus astacus (Linné), using twelve pelleted diets containing various combinations of protein (22, 31 or 40%), lipid (5.5–16%) and carbohydrate (9.2–25.8%) in a 394-day experiment. The diets ranged from 241 to 321 kcal/100 g feed and with protein/energy (P/E) ratios of 69 to 153 mg/kcal. The experiments were carried out in a closed system with constant temperature; dissolved nitrogen, oxygen content, pH and water temperature were monitored. All diets with 40% protein gave a good survival rate. The diet with 31% protein, moderately high carbohydrate (16.6%) and a low lipid content (7%) promoted a high survival rate as well. At the 22% protein level, the feed with high lipid content (16%) gave a poor survival rate. The mean biomass increase was greatest with all diets with 40% protein and those diets with 31% protein, high carbohydrate level and low lipid content. Younger juveniles demonstrated the highest growth rate on 40% protein diets and 31% protein diets, when the latter containedP/E ratios in the range 114 to 153 mg/kcal. At the 22% protein level growth was poor. Optimum biomass gain was obtained withP/E ratios above 114 mg/kcal. Optimum lipid/carbohydrate ratios changed with protein content of the feed. Lipid levels above 10% in diets containing 31 and 22% protein depressed the growth rate of younger animals. With increasing physiological age, the animals responded favourably to higher lipid and carbohydrate levels.

CHEMICAL CHANGES AND SENSORY EVALUATION OF CHANNEL CATFISH AS AFFECTED BY DIET, PACKAGING METHOD AND FROZEN STORAGE

AbstractFillets from farm‐raised channel catfish (Ictalurum punctatus) fed diets containing various amounts of protein were packaged by the following methods: polyvinylidene chloride (PVDC) film overwrapping, vacuum packaging with Eva bag and vacuum skin packaging. Packaged fillets were stored at —28C for 90 days. Chemical and sensory changes were determined. Neither the packaging method nor protein content of diet had a significant (p < 0.05) effect on TBA number of frozen stored catfish. No significant differences on free fatty acid content of catfish packaged in different methods were also found. However, sensory evaluation revealed that greasiness of cooked catfish decreased as toughness of fillet texture increased throughout entire frozen storage.

Immobilization of proteins to a carboxymethyldextran-modified gold surface for biospecific interaction analysis in surface plasmon resonance sensors

A method for fast and simple covalent immobilization of proteins to a carboxymethyldextran-modified gold surface intended for surface plasmon resonance sensors is described. The method utilizes the formation of N-hydroxysuccinimide esters from a fraction of the carboxyl groups of the carboxymethyldextran matrix via reaction with N-hydroxysuccinimide and N-ethyl- N′-(dimethylaminopropyl) carbodiimide hydrochloride in water. In a second step the protein is passed over the surface in a solution of low ionic strength with a pH value below the isoelectric point of the protein. The protein is thereby concentrated in the matrix by electrostatic attraction forces and a simultaneous reaction with the active esters takes place. In a final step, the remaining active esters are transformed into amides via reaction with ethanolamine. This sequence is performed automatically in a system comprising an integrated microfluidic cartridge and an autosampler. Typical reaction times of less than 30 min are required for the immobilization of proteins at surface concentrations in the region of 70 fmol mm −2. Parameters such as protein concentration, protein solution ionic strength, pH, reaction times, and reagent concentration can be varied in order to control the immobilized amount of ligand. The biospecific interaction of the immobilized ligand with its biological counterpart is illustrated by the effects on the interaction of immunoglobulins with immobilized Staphylococcus aureus protein A for various amounts of protein A.

Immunological methods in molecular palaeontology

Variable amounts of proteins or protein fragments may survive in fossils for thousands and occasionally millions of years. The quantities are generally too small to determine accurate amino acid sequences, but even these small amounts may be immunologically detectable and may retain useful genetic information. A very sensitive solid phase radioimmunoassay has been used to analyse fossil proteins, particularly albumin and collagen, the most abundant animal proteins and those most likely to be found in fossil skin, muscle, bones and teeth. Species-specific proteins have been identified in the skin and muscle of mammoth, quagga and Tasmanian wolf, and in the bones of the extinct mastodon and Steller’s sea cow. Specific albumin has also been detected in bloodstains on ancient stone weapons and in fossilized urine from the middens of cave-dwelling pack rats, porcupines and hyraxes.

Metabolic response to glucose ingested with various amounts of protein

Seven healthy, normal-weight subjects were fed breakfasts of 50 g protein, 50 g glucose, and 10, 30, or 50 g protein plus 50 g glucose in random sequence. Plasma glucose, insulin, C peptide, glucagon, nonesterified fatty acids, and alpha-amino nitrogen were then measured from samples obtained over 4 h. The postmeal net area of each response curve was calculated. Ingestion of 50 g protein alone did not change the serum glucose concentration. The various amounts of protein ingested with 50 g glucose also did not alter the serum glucose response compared with that observed with 50 g glucose alone. Ingestion of the various amounts of protein also did not result in a further increase in insulin concentration when ingested with glucose, except with the 50-g-protein dose. This increase was modest. Ingestion of glucose resulted in a decrease in alpha-amino nitrogen and glucagon concentrations whereas ingestion of protein increased them as expected. Additions of progressively larger amounts of protein to the glucose meal resulted in a progressive increase in the alpha-amino-nitrogen- and glucagon-area responses. The relationship was curvilinear for both the alpha-amino-nitrogen response and the glucagon response. The null point, that is, the protein dose ingested with 50 g glucose at which there would be no change in area response, was estimated to be 9 g protein for alpha-amino nitrogen and 5 g protein for glucagon.

Quantitative extraction and purification of exopolysaccharides from Klebsiella pneumoniae

Klebseilla pneumoniae (O1:K2) exopolysaccharides were extracted with a zwitterionic detergent in citrate buffer (pH 4.5). The mild procedure released nearly 95% of the capsular polysaccharide and 60–70% of the lipopolysaccharide. Variable amounts of protein were extracted with the polysaccharides, while very little of the nucleic acid was found in the extract. Gel filtration chromatography of the polysaccharide extract, without a buffer exchange step, resulted in high recovery purification of capsular and lipopolysaccharides. The extraction led to minimal cell disruption, was shown by the light and electron microscopy, by studies of viability, and by plasmid DNA isolation. Plasmids isolated before detergent extraction were seen to smear on agarose gels, due to interaction with polysaccharides, while plasmids from extracted cells exhibited tight banding patterns. Both ionic and hydrophobic interactions appear responsible for the structural stability of the K. pneumoniae capsule.