Carbohydrates hexoses

Depending on the preparative method used, the membrane may or may not contain skim-milk proteins (i.e. caseins and whey proteins) if the membrane has been damaged prior to isolation, it may contain considerable amounts of these proteins. The membrane contains unique proteins which do not occur in the skim-milk phase. Many of the proteins are glycoproteins and contain a considerable amount of carbohydrate (hexose, 2.8-4.15% hexosamine, 2.5-4.2% and sialic acid, 1.3—1.8%). 

Fig. 2. Stereoview of the three-dimensional structure of human IgG myeloma protein Dob. The smaller circles represent a-carbon atoms the larger circles represent carbohydrate hexose units. The Fab arms of the molecule are aligned vertically, and a horizontal twofold axis of symmetry bisects the molecule through the Fc. In this view the light chain is in the foreground of the upper Fab, and the heavy chains in the foreground of the lower Fab compare with Fig. 1. From Silverton el... 

Ceruloplasmin, the copper protein in plasma, deserves special attention. Human plasma contains approximately 32 mg/100 ml of this protein (see Table 6) (C2, C12, R4). According to the recent careful measurements of Kasper and Deutsch (K3), the molecular weight of ceruloplasmin is 160,000, somewhat higher than the 151,000 obtained by Pedersen (P3). Ceruloplasmin is an a2-globulin and contains 8 atoms of copper per molecule (H14). In addition to being a metalloprotein, it is a glycoprotein containing 7% carbohydrate hexose, hexosamine, and neuraminic acid (L4). Ceruloplasmin has been prepared in a pure form from human and pig sera (H14). Several newer methods are now available for its isolation and purification (B29, C20, D4, L4, S4, S7, S39). 

Fig. 6. Structure of the Fc fragment of human IgG. ( ), Alpha carbon positions (o), approximate centres of carbohydrate hexose units. Coordinates were obtained from the Brookhaven Data Bank (after Dei-senhofer [23]). The pairing of Cn3 domains and the position of carbohydrate between C 2 domains is clearly seen in this view. The contact between carbohydrate chains is much more extensive in rabbit Fc. Note that the heavy chains are described only from residue 238 residues 225-238 do not show well-defined electron density.

Protein Total carbohydrate (%) Hexose ( ) Serum concentration (mg/100 ml) Carbohydrate- protein linkage ... 

Bioethanol is produced from the hydrolysate of lignocellulosic substrate after pretreatment and enzymatic hydrolysis. With high conversion of carbohydrates, hexose and pentose can be fermented by commercial or engineered Saccharomyces cerevisiae or other microorganisms. Depending on the feedstock and pretreatment processes, various types of growth-inhibiting compounds have been discovered to hinder the performance of fermentation. For example, HMF and furfural formed from dehydration of... 

The oldest fermentation process known uses modem technology today and produces e. from all kinds of carbohydrates (hexoses, pentoses, hydrolyzed starch, sucrose and cellulose and waste liquor from - paper pulping) in aqueous solution with the aid of living yeast (Species of Saccharo-myces, Candida and Kluyveromyces) ... 

The best examples of substances with multiple chirality centers are the carbohy drates (Chapter 25) One class of carbohydrates called hexoses has the constitution... 

The two stereoisomeric furanose forms of d erythrose are named a d erythro furanose and p d erythrofuranose The prefixes a and p describe fhe relative configu ration of fhe anomeric carbon The configurafion of fhe anomeric carbon is compared wifh fhaf of fhe highesf numbered chiralify cenfer m fhe molecule—fhe one fhaf defer mines whefher fhe carbohydrafe is d or l Chemisfs use a simplified informal version of fhe lUPAC rules for assigning a and p fhaf holds for carbohydrates up fo and mclud mg hexoses... 

Heterogeneous reaction (Section 6 1) A reaction involving two or more substances present in different phases Hydro genation of alkenes is a heterogeneous reaction that takes place on the surface of an insoluble metal catalyst Heterolytic cleavage (Section 4 16) Dissociation of a two electron covalent bond in such a way that both electrons are retained by one of the initially bonded atoms Hexose (Section 25 4) A carbohydrate with six carbon atoms High density lipoprotein (HDL) (Section 26 11) A protein that carries cholesterol from the tissues to the liver where it is metabolized HDL is often called good cholesterol Histones (Section 28 9) Proteins that are associated with DNA in nucleosomes... 

Properties and Structure. a -Acid glycoprotein (a -AGP) has a molecular mass of about 41,000 and consists of a peptide chain having 181 amino acid residues and five carbohydrate units (14,15). Two cystine disulfide cross-linkages connect residues 5 and 147 and residues 72 and 164. The carbohydrate units comprise 45% of the molecule and contain siaUc acid, hexosamine, and neutral hexoses. In phosphate buffer the isoelectric point of the... 

In the presence of lime water more complex reactions occur, leading to the formation of aldoses and hexoses (iv). This particular reaction is of interest to the biochemist as it is now generally held that optically active plant carbohydrates are obtained from carbon dioxide and water via formaldehyde. 

Hexose (Section 25.4) A carbohydrate with six carbon atoms. 

The set of reactions that transforms 3-phosphoglycerate into hexose is named the Calvin-Benson cycle (often referred to simply as the Calvin cycle) for its discoverers. The reaction series is indeed cyclic because not only must carbohydrate appear as an end product, but the 5-carbon acceptor, RuBP, must be regenerated to provide for continual COg fixation. Balanced equations that schematically represent this situation are... 

Pyruvate ketals add to the anionic nature of the exopolysaccharide and are usually present in stoichiometric ratios with the carbohydrate component Pyruvate is normally attached to the neutral hexoses but may also be attached to uronic adds. In the absence of uronic acids, pyruvate alone contributes to the anionic nature of the exopolysaccharide. 

The Enzymes II (E-IIs) of the phosphoenolpyruvate (P-enolpyruvate)-dependent phosphotransferase system (PTS) are carbohydrate transporters found only in prokaryotes. They not only transport hexoses and hexitols, but also pentitols and disaccharides. The PTS substrates are listed in Table I. The abbreviations used (as superscripts) throughout the text for these substrates are as follows Bgl, jS-gluco-side Cel, cellobiose Fru, fructose Glc, glucose Gut, glucitol Lac, lactose Man, mannose Mtl, mannitol Nag, iV-acetylglucosamine Scr, sucrose Sor, sorbose Xtl, xylitol. 

Attack of the OH radical on carbohydrates of low molecular mass gives rise to a variety of products. Indeed, the reaction of radiolytically-generated OH radical with lower hexose sugars produces lower saccharides (for di- and higher saccharide species), uronic and aldonic acids, and 3-, 2- and 1-carbon aldehydic fragments, e.g. 

Based on these results, a novel method for the synthesis of hexose-6-aldehydes from natural carbohydrate sources has been developed by us. Preliminary results for the regioselective oxidation of the primaty alcohol group in glycosides by the dinuclear copper(ll) complex N, A-bis[(2-pyridylmethyl)-l,3-diaminopropan-2-olato] (p-acetato) dicopper(ll) perchlorate (Cu2(bpdpo), (4) are described below. 

There is known one more catabolic route for carbohydrates commonly referred to as the pentose phosphate cycle (also called hexose mono phosphate shunt, or phosphogluconate pathway). 

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