Hepatic autoregulation: response of glucose production and gluconeogenesis to increased glycogenolysis

The effect of increased glycogenolysis, simulated by galactose's conversion to glucose, on the contribution of gluconeogenesis (GNG) to hepatic glucose production (GP) was determined. The conversion of galactose to glucose is by the same pathway as glycogen's conversion to glucose, i.e., glucose 1-phosphate --> glucose 6-phosphate --> glucose. Healthy men (n = 7) were fasted for 44 h. At 40 h, hepatic glycogen stores were depleted. GNG then contributed approximately 90% to a GP of approximately 8 micromol.kg(-1).min(-1). Galactose, 9 g/h, was infused over the next 4 h. The contribution of GNG to GP declined from approximately 90% to 65%, i.e., by approximately 2 micromol.kg(-1).min(-1). The rate of galactose conversion to blood glucose, measured by labeling the infused galactose with [1-(2)H]galactose (n = 4), was also approximately 2 micromol.kg(-1).min(-1). The 41st h GP rose by approximately 1.5 micromol.kg(-1).min(-1) and then returned to approximately 9 micromol.kg(-1).min(-1), while plasma glucose concentration increased from approximately 4.5 to 5.3 mM, accompanied by a rise in plasma insulin concentration. Over 50% of the galactose infused was accounted for in blood glucose and hepatic glycogen formation. Thus an increase in the rate of GP via the glycogenolytic pathway resulted in a concomitant decrease in the rate of GP via GNG. While the compensatory response to the galactose administration was not complete, since GP increased, hepatic autoregulation is operative in healthy humans during prolonged fasting.     

Water-soluble polysaccharides from Salvia officinalis L. possessing immunomodulatory activity

A water-soluble polysaccharide complex (A) composed of galactose (17.9%), 3-O-methyl-galactose (3.0%), glucose (15.5%), mannose (8.3%), arabinose (30.4%), xylose (7.6%), fucose (2.6%), rhamnose (6.7%), and uronic acids (8.0%) has been isolated from the aerial parts of sage (Salvia officinalis L.) by cold water extraction. It showed a broad molecular-mass distribution pattern (Mw approximately 2000-93,000) with a predominance of polymers with Mw< 10,000. Ion-exchange chromatography of A afforded six polymeric fractions (A1-A6) in which arabinogalactans associated with galacturonan and/or rhamnogalacturonan backbones prevail. Sage polysaccharides were examined for their immunomodulatory activity in the comitogenic thymocyte test which is interpreted as being an in vitro correlate of adjuvant activity. The acidic polysaccharide fractions A2, A3 and A4 exhibited the highest mitogenic and comitogenic activities of all fractions tested, and relatively high SI(comit)/SI(mit) ratios approximately 3 indicate potential adjuvant properties of these polysaccharides.     

Formation of the Dictyostelium spore coat

The spore coat forms as a rigid extracellular wall around each spore cell during culmination. Coats purified from germinated spores contain multiple protein species and an approximately equal mass of polysaccharide, consisting mostly of cellulose and a galactose/N-acetylgalactosamine polysaccharide (GPS). All but the cellulose are prepackaged during prespore cell differentiation in a regulated secretory compartment, the prespore vesicle. The morphology of this compartment resembles an anastomosing, tubular network rather than a spherical vesicle. The molecules of the prespore vesicles are not uniformly mixed but are segregated into partially overlapping domains. Although lysosomal enzymes have been found in the prespore vesicle, this compartment does not function as a lysosome because it is not acidic, and a common antigen associated with acid hydrolases is found in another, acidic vesicle population. All the prespore vesicle profiles disappear at the time of appearance of their contents outside of the cell; this constitutes an early stage in spore coat formation, which can be detected both by microscopy and flow cytometry. As an electron-dense layer, the future outer layer of the coat, condenses, cellulose can be found and is located immediately beneath this outer layer. Certain proteins and the GPS become associated with either the outer or inner layers surrounding this middle cellulose layer. Assembly of the inner and outer layers occurs in part from a pool of glycoproteins that is shared between spores, and unincorporated molecules loosely reside in the interspore matrix, a location from which they can be easily washed away. When the glycosylation of several major protein species is disrupted by mutation, the coat is assembled, but differences are found in its porosity and the extractibility of certain proteins. In addition, the retention or loss of proteolytic fragments in the mutants indicates regions of spore coat proteins that are required for association with the coat. Comparative examination of the macrocyst demonstrates that patterns of molecular distributions are not conserved between the macrocyst and spore coats. Thus spore coat assembly is characterized by highly specific intermolecular interactions, leading to saturable associations of individual glycoproteins with specific layers and the exclusion of excess copies to the interspore space.     

Exopolysaccharide Distribution of and Bioemulsifier Production by Acinetobacter calcoaceticus BD4 and BD413

The heavily encapsulated Acinetobacter calcoaceticus BD4 and the “miniencapsulated” single-step mutant A. calcoaceticus BD413 produced extracellular polysaccharides in addition to the capsular material. The molar ratio of rhamnose to glucose (3:1) in the extracellular BD413 polysaccharide fraction was similar to the composition of the capsular material. In both strains, the increase in capsular polysaccharide was parallel to cell growth and remained constant in stationary phase. The extracellular polysaccharides were detected starting from mid-logarithmic phase and continued to accumulate in the growth medium for 5 to 8 h after the onset of stationary phase. Strain BD413 produced one-fourth the total rhamnose exopolysaccharide per cell that strain BD4 did. Depending on the growth medium, 32 to 63% of the rhamnose polysaccharide produced by strain BD413 was extracellular, whereas in strain BD4 only 7 to 14% was extracellular. In all cases, strain BD413 produced more extracellular rhamnose polysaccharide than strain BD4 did. In glucose medium, strain BD413 also produced approximately 10 times more extracellular emulsifying activity than strain BD4 did. The isolated capsular polysaccharide obtained after shearing of BD4 cells showed no emulsifying activity. Thus, strain BD413 either produces a modified extracellular polysaccharide or excretes an additional substance(s) that is responsible for the emulsifying activity. Emulsions induced by the ammonium sulfate-precipitated BD413 extracellular emulsifier require the presence of magnesium ion and a mixture of an aliphatic and an aromatic hydrocarbon.     

Prolonged exposure to palmitate impairs fatty acid oxidation despite activation of AMP-activated protein kinase in skeletal muscle cells

The aim of this study was to investigate the chronic effects of palmitate on fatty acid (FA) oxidation, AMPK/ACC phosphorylation/activation, intracellular lipid accumulation, and the molecular mechanisms involved in these processes in skeletal muscle cells. Exposure of L6 myotubes for 8 h to 200, 400, 600, and 800 microM of palmitate did not affect cell viability but significantly reduced FA oxidation by approximately 26.5%, approximately 43.5%, approximately 50%, and approximately 47%, respectively. Interestingly, this occurred despite significant increases in AMPK ( approximately 2.5-fold) and ACC ( approximately 3-fold) phosphorylation and in malonyl-CoA decarboxylase activity ( approximately 38-60%). Low concentrations of palmitate (50-100 microM) caused an increase ( approximately 30%) in CPT-1 activity. However, as the concentration of palmitate increased, CPT-1 activity decreased by approximately 32% after exposure for 8 h to 800 microM of palmitate. Although FA uptake was reduced ( approximately 35%) in cells exposed to increasing palmitate concentrations, intracellular lipid accumulation increased in a dose-dependent manner, reaching values approximately 2.3-, approximately 3-, and 4-fold higher than control in muscle cells exposed to 400, 600, and 800 microM palmitate, respectively. Interestingly, myotubes exposed to 400 microM of palmitate for 1 h increased basal glucose uptake and glycogen synthesis by approximately 40%. However, as time of incubation in the presence of palmitate progressed from 1 to 8 h, these increases were abolished and a time-dependent inhibition of insulin-stimulated glucose uptake ( approximately 65%) and glycogen synthesis ( approximately 30%) was observed in myotubes. These findings may help explain the dysfunctional adaptations that occur in glucose and FA metabolism in skeletal muscle under conditions of chronically elevated circulating levels of non-esterified FAs, such as in obesity and Type 2 Diabetes.     

Epinephrine inhibits exogenous glucose utilization in exercising horses.

This study examined the effects of preexercise glucose administration, with and without epinephrine infusion, on carbohydrate metabolism in horses during exercise. Six horses completed 60 min of treadmill exercise at 55 +/- 1% maximum O(2) uptake 1) 1 h after oral administration of glucose (2 g/kg; G trial); 2) 1 h after oral glucose and with an intravenous infusion of epinephrine (0.2 micromol. kg(-1). min(-1); GE trial) during exercise, and 3) 1 h after water only (F trial). Glucose administration (G and GE) caused hyperinsulinemia and hyperglycemia ( approximately 8 mM). In GE, plasma epinephrine concentrations were three- to fourfold higher than in the other trials. Compared with F, the glucose rate of appearance was approximately 50% and approximately 33% higher in G and GE, respectively, during exercise. The glucose rate of disappearance was approximately 100% higher in G than in F, but epinephrine infusion completely inhibited the increase in glucose uptake associated with glucose administration. Muscle glycogen utilization was higher in GE [349 +/- 44 mmol/kg dry muscle (dm)] than in F (218 +/- 28 mmol/kg dm) and G (201 +/- 35 mmol/kg dm). We conclude that 1) preexercise glucose augments utilization of plasma glucose in horses during moderate-intensity exercise but does not alter muscle glycogen usage and 2) increased circulating epinephrine inhibits the increase in glucose rate of disappearance associated with preexercise glucose administration and increases reliance on muscle glycogen for energy transduction.     

Chemical characterization of the component of the jelly coat from sea urchin eggs responsible for induction of the acrosome reaction.

Jelly coat, a multicomponent extracellular matrix surrounding the sea urchin egg, induces the acrosome reaction in sperm. The jelly coats of the four species studied, Arbacia punctulata, Strongylocentrotus purpuratus, Strongylocentrotus drobachiensis, and Lytechinus variegatus, were found to be very similar in chemical composition. A sialoprotein (approximately 20% of the mass of the jelly coat) and a fucose sulfate polysaccharide (approximately 80%) are the major macromolecular components of the jelly coat. The acrosome reaction inducing capacity resides solely in the fucose sulfate polysaccharide. Induction of the acrosome reaction ranges from highly species specific to nonspecific. Thus, A. punctulata and S. drobachiensis sperm are induced to undergo the acrosome reaction only with their homologous jelly coat, while S. purpuratus sperm react equally well with homologous or L. variegatus jelly coat, but not with A. punctulata jelly coat. L. variegatus sperm seem to be relatively nonspecific in response. Species-specific induction of the acrosome reaction resides solely in the fucose sulfate polysaccharide, suggesting that there must be structural differences in this polysaccharide in the various species. Therefore, in some species, fertilization appears to involve sperm-egg recognition at the level of the jelly coat as well as at the level of sperm-egg receptors.     

Isolation and characterization of a galactorhamnan polysaccharide from the seed coat of Canavalia ensiformis that is toxic to the cowpea weevil (Callosobruchus maculatus)

We have isolated a water-soluble polysaccharide from the Jack bean [Canavalia ensiformis (L) DC] seed coat that was shown to be highly detrimental to larval development of the cowpea weevil (Callosobruchus maculatus) (Coleoptera: Bruchidae). Determination of the composition and structure of this polysaccharide showed that it is a galactorhamnan with an M_w of 883.0, containing 92% rhamnose and 8% galactose. The polymer is formed by a main chain of rhamnose (1to2) substituted at O-4 by galactose nonreducing end-units. Immunolocalisation by light and electron microscopy showed that this polysaccharide is localised in the innermost cell layer of the seed coat and also in cotyledon tissues in the cytoplasm space. The presence of this toxic polysaccharide in the testa of a non-host seed may have been important for the evolutionary discrimination of legume seeds by bruchids.     

Study of the extracellular polysaccharides produced by a blue-green alga,Anabaena flos-aquae A-37

Summary Two types of polysaccharides were separated from the extracellular polysaccharide produced by Anabaena flos-aquae A-37 by ion exchange chromatography. The neutral polysaccharide is composed of mainly glucose with minor amounts of xylose in a molar ratio of 8:1. Glucose is believed to constitute the polysaccharide core to which xylose is attached. The acidic polysaccharide is composed of glucose and uronic acid as the major monomers with equal amounts of xylose and ribose as the minor constituents. The molar ratio of the monomers found in the acidic polymer is 6:1:1:10 as glucose: xylose: ribose: uronic acid. Chemical analyses showed that the extracellular polysaccharide consists of more neutral polymer (62%) than the acidic polymer (38%).     

Reactive oxygen species production by mitochondria in endothelial cells exposed to reoxygenation after hypoxia and glucose depletion is mediated by ceramide

In endothelium, reoxygenation after hypoxia (H/R) has been shown to induce production of reactive oxygen species (ROS) by complex III of the mitochondrial respiratory chain. The purpose of the present study was to test the involvement of ceramide in this phenomenon. Human umbilical vein endothelial cells underwent 2 h of hypoxia (PO2, approximately 20 mmHg) without glucose and 1 h of reoxygenation (PO2, approximately 120 mmHg) with glucose. ROS production was measured by the fluorescent marker 2',7'-dichlorodihydrofluorescein diacetate, and cell death by propidium iodide. We showed that 1) after 1 h of reoxygenation, fluorescence had risen and that ROS production was inhibited by desipramine, an inhibitor of sphingomyelinase, an enzyme responsible for ceramide production (126 +/- 7% vs. 48 +/- 12%, P < 0.05); 2) administration of ceramide (N-acetylsphingosine) per se (i.e., in the absence of H/R) induced ROS production (65 +/- 3%), which was inhibited by complex III inhibitor: antimycin A (24 +/- 3%, P < 0.0001), or stigmatellin (31 +/- 2%, P < 0.0001); 3) hypoxia/reoxygenation-induced ROS production was not affected by either ceramide-activated protein kinase inhibitor dimethyl aminopurine or mitochondrial permeability transition inhibitor cyclosporin A but was significantly inhibited by the antiapoptotic protein Bcl-2 (82 +/- 8%, P < 0.05); 4) ceramide-induced ROS production was also inhibited by Bcl-2 (41 +/- 4%, P < 0.0001). These results demonstrate that in endothelial cells submitted to hypoxia and glucose depletion followed by reoxygenation with glucose, the pathway implicated in mitochondrial complex III ROS production is ceramide dependent and is decreased by the antiapoptotic protein Bcl-2.     

Time course of the hepatic adaptation to TPN: interaction with glycogen depletion

In response to chronic (5 days) TPN, the liver becomes a major site of glucose disposal, removing approximately 45% (4.5 mg.kg(-1).min(-1)) of exogenous glucose. Moreover, approximately 70% of glucose is not stored but released as lactate. We aimed to determine in chronically catheterized conscious dogs the time course of adaptation to TPN and the glycogen depletion impact on early time course. After an 18-h (n = 5) fast, TPN was infused into the inferior vena cava for 8 (n = 5) or 24 h (n = 6). A third group, of 42-h-fasted animals (n = 6), was infused with TPN for 8 h. TPN was infused at a rate designed to match the dog's calculated basal energy and nitrogen requirements. NHGU (-2.3 +/- 0.1 to 2.2 +/- 0.7 to 3.9 +/- 0.6 vs. -1.7 +/- 0.3 to 1.1 +/- 0.5 to 2.9 +/- 0.4 mg.kg(-1).min(-1), basal to 4 to 8 h, 18 vs. 42 h) and net hepatic lactate release (0.7 +/- 0.3 to 0.6 +/- 0.1 to 1.4 +/- 0.2 vs. -0.6 +/- 0.1 to 0.1 +/- 0.1 to 0.8 +/- 0.1 mg.kg(-1).min(-1), basal to 4 to 8 h) increased progressively. Net hepatic glycogen repletion and tracer determined that glycogen syntheses were similar. After 24 h of TPN, NHGU (5.4 +/- 0.6 mg.kg(-1).min(-1)) and net hepatic lactate release (2.6 +/- 0.4 mg.kg(-1).min(-1)) increased further. In summary, 1) most hepatic adaptation to TPN occurs within 24 h after initiation of TPN, and 2) prior glycogen depletion does not augment hepatic adaptation rate.     

千斤拔多糖的提取纯化及其结构鉴定

利用正交试验考察千斤拔多糖的提取工艺,并比较脱蛋白方法中的Sevag法和三氯乙酸法的纯化效果,总糖含量测定采用苯酚-硫酸法,蛋白质含量测定采用考马斯亮蓝法;采用DEAE-52纤维柱法来分离多糖,并运用HPLC色谱来分析千斤拔多糖中的单糖成分。结果表明:经正交试验得出千斤拔多糖的最佳提取条件为时间2.5 h,料液比为1∶30,温度80℃,其多糖得率为8.558%。对比两种脱蛋白的方法,Sevage法萃取3次时蛋白的脱除效果最好。经DEAE-52纤维柱来分离多糖共分得7个组分。经HPLC色谱鉴定出有葡萄糖,甘露糖和阿拉伯糖,主要单糖成分为葡萄糖。     

Characterization and enzymatic hydrolysis of hydrothermally treated β-1,3–1,6-glucan from <Emphasis Type="Italic">Aureobasidium pullulans</Emphasis>

The chemical structure of hydrothermally treated β-1,3–1,6-glucan from Aureobasidium pullulans was characterized using techniques such as gas chromatography/mass spectrometry (GC/MS) and nuclear magnetic resonance (NMR). The chemical shifts of anomeric carbons observed in the ¹³C-NMR spectra suggested the presence of single flexible chains of polysaccharide in the sample. β-1,3–1,6-Glucan from A. pullulans became water-soluble, with an average molecular weight of 128,000 Da after hydrothermal treatment, and the solubility in water was approximately 10% (w/w). Sample (3% w/v) was completely hydrolyzed to glucose by enzymatic reaction with Lysing enzymes from Trichoderma harzianum. Gentiobiose (Glcβ1 → 6Glc) and glucose were released as products during the reaction, and the maximum yield of gentiobiose was approximately 70% (w/w). The molar ratio of gentiobiose to glucose after 1 h reaction suggested that the sample is likely highly branched. Sample (3% w/v) was also hydrolyzed to glucose by Uskizyme from Trichoderma sp., indicating that it is very sensitive to enzymatic hydrolysis.     

红托竹荪菌托多糖提取工艺及抗氧化降血糖活性

为利用红托竹荪菌托,采用酶解法提取菌托多糖,优化多糖提取工艺,并测定多糖分子量、单糖组成、抗氧化及降血糖活性。结果表明,最佳酶解法提取工艺为纤维素酶2.5%、果胶酶0.4%、木瓜蛋白酶1.5%,50 ℃酶解1 h,料液比1:60、提取温度80 ℃、时间3 h,该条件下多糖提取率达15.37%,比热水浸提法提高39.60%。酶解法多糖分子量为3 344 Da (Mn)、522 208 Da (Mw)、2 929 Da (Mp),主要由葡萄糖、甘露糖、葡萄糖醛酸、半乳糖和岩藻糖等组成,葡萄糖占最高,达48.82%。菌托多糖为2.0 mg/mL时,DPPH·清除率为93.83%,Fe³⁺还原能力为0.140 7,α-葡萄糖苷酶活性抑制率为54.62%、α-淀粉酶活性抑制率为56.45%,与热水浸提法相比差异极显著或显著。酶解法提取红托竹荪菌托多糖,提取率较高,具有较高的抗氧化、降血糖活性,具有推广应用价值。     

Structural determination and biosynthetic studies of the O-antigenic polysaccharide from the enterohemorrhagic Escherichia coli O91 using 13C-enrichment and NMR spectroscopy.

The structure of the O-antigenic polysaccharide from the enterohemorrhagic Escherichia coli O91 has been determined using primarily NMR spectroscopy on the (13)C-enriched polysaccharide. The O-antigen is composed of pentasaccharide repeating units with the following structure: -->4)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->4)-beta-D-GlcpA-6-N- Gly -(1-->3)-beta-D-GlcpNAc-(1-->4)-alpha-D-Quip-3-N-[(R)-3-hydroxy butyra mido]-(1-->. The bacterium was grown with D-[UL-(13)C]glucose in the medium which resulted in an overall degree of labeling of approximately 65% in the sugar residues and approximately 50% in the N-acyl substituents, indicating some metabolic dilution in the latter. The (13)C-enrichment of the polysaccharide proved valuable since NMR assignments could be made on the basis of (13)C, (13)C-connectivity in uniformly labeled residues. The biosynthesis of the (R)-3-hydroxybutyramido substituent via C(2) fragments was identified by NMR spectroscopy. The (R)-configuration at C3 is in accord with fatty acid biosynthesis. Additional cultures with specifically labeled D-[1-(13)C]glucose or D-[6-(13)C]glucose corroborated the direct incorporation of glucose as the building block for the hexose skeletons in the polysaccharide and the biosynthesis of acyl substituents occurring via the triose pool followed by decarboxylation to give acetyl building blocks labeled with (13)C at the methyl group.     

Route-dependent effect of nutritional support on liver glucose uptake

The liver is a major site of glucose disposal during chronic (5 day) total parenteral (TPN) and enteral (TEN) nutrition. Net hepatic glucose uptake (NHGU) is dependent on the route of delivery when only glucose is delivered acutely; however, the hepatic response to chronic TPN and TEN is very similar. We aimed to determine whether the route of nutrient delivery altered the acute (first 8 h) response of the liver and whether chronic enteral delivery of glucose alone could augment the adaptive response to TPN. Chronically catheterized conscious dogs received either TPN or TEN containing glucose, Intralipid, and Travasol for either 8 h or 5 days. Another group received TPN for 5 days, but approximately 50% of the glucose in the nutrition was given via the enteral route (TPN+EG). Hepatic metabolism was assessed with tracer and arteriovenous difference techniques. In the presence of similar arterial plasma glucose levels (approximately 6 mM), NHGU and net hepatic lactate release increased approximately twofold between 8 h and 5 days in TPN and TEN. NHGU (26 +/- 1 vs. 23 +/- 3 micromol.kg(-1).min(-1)) and net hepatic lactate release (44 +/- 1 vs. 34 +/- 6 micromol.kg(-1).min(-1)) in TPN+EG were similar to results for TPN, despite lower insulin levels (96 +/- 6 vs. 58 +/- 16 pM, TPN vs. TPN+EG). TEN does not acutely enhance NHGU or disposition above that seen with TPN. However, partial delivery of enteral glucose is effective in decreasing the insulin requirement during chronic TPN.     

Estimation of gluconeogenesis in newborn infants

The rate of glucose turnover (R(a)) and gluconeogenesis (GNG) via pyruvate were quantified in seven full-term healthy babies between 24 and 48 h after birth and in twelve low-birth-weight infants on days 3 and 4 by use of [(13)C(6)]glucose and (2)H(2)O. The preterm babies were receiving parenteral alimentation of either glucose or glucose plus amino acid with or without lipids. The contribution of GNG to glucose production was measured by the appearance of (2)H on C-6 of glucose. Glucose R(a) in full-term babies was 30 +/- 1.7 (SD) micromol. kg(-1). min(-1). GNG via pyruvate contributed approximately 31% to glucose R(a). In preterm babies, the contribution of GNG to endogenous glucose R(a) was variable (range 6-60%). The highest contribution was in infants receiving low rates of exogenous glucose infusion. In an additional group of infants of normal and diabetic mothers, lactate turnover and its incorporation into glucose were measured within 4-24 h of birth by use of [(13)C(3)]lactate tracer. The rate of lactate turnover was 38 micromol. kg(-1). min(-1), and lactate C, not corrected for loss of tracer in the tricarboxylic acid cycle, contributed approximately 18% to glucose C. Lactate and glucose kinetics were similar in infants that were small for their gestational age and in normal infants or infants of diabetic mothers. These data show that gluconeogenesis is evident soon after birth in the newborn infant and that, even after a brief fast (5 h), GNG via pyruvate makes a significant contribution to glucose production in healthy full-term infants. These data may have important implications for the nutritional support of the healthy and sick newborn infant.     

Flocculant and Chemical Properties of a Polysaccharide from Pullularia pullulans

An extracellular polysaccharide, PP-floc, was synthesized from glucose by Pullularia pullulans (or Aureobasidium pullulans) in a pilot plant batch fermentor containing 175 liters of culture medium. At 58 h of fermentation, the concentration of PP-floc was 1.03 g/100 ml, giving a 25.8% conversion of initial glucose to polysaccharide. The flocculant activity of the culture medium increased during the fermentation process and reached its maximum at 50 h of culture age. Less PP-floc (0.33 lb/ton of slimes [approximately 149.7 g/0.907 t]) was required to give the same flocculant activity as a synthetic polymer of acrylamide, Separan NP-10 (0.5 lb/ton of slimes [approximately 226.8 g/0.907 t]), at all temperatures from 25 to 100 C. The degree of inactivation of PP-floc and Separan NP-10 at elevated temperatures was almost identical, and they were completely inactivated at about the same temperature (80 C). PP-floc also gave better compaction of slimes than Separan NP-10 at all temperatures tested. PP-floc was soluble in water and its specific optical rotation was [alpha](D) (25) + 194 degrees in water (c, 0.4). PP-floc contained 83.3% carbohydrate, 3.2% protein, and 8.1% water. Glucose was found to be the principal sugar monomer with traces (>5%) of galactose and mannose present. Structural studies on the fractions of purified polysaccharide by methylation and by periodate oxidation techniques prove that PP-floc is linear and composed of alpha-(1 --> 4) and alpha-(1 --> 6) glucopyranosyl units in the approximate ratio of 2:1. The action of pullulanase on crude PP-floc suggested the ordered arrangement of two consecutive alpha-(1 --> 4)-linked glucopyranosyl units flanked by alpha-(1 --> 6)-linked glucopyranose residues.