Insulin fraction

Sanger and Tuppy (1951a) studied an alkaline hydrolyzate of an oxidized insulin fraction. Although the conditions used would not have been expected to cause any destruction of free serine or threonine, it was evident that most of these residues in the protein had been broken down. Thus, for instance, Gly.Pro was found in the alkaline hydrolyzate whereas Thr.Pro was present in the acid hydrolyzate. The arginine residues were also converted to ornithine (or citrulline). 

Brewers and bakers dried yeasts are used as dietary supplements. They contribute some protein and trace minerals, and some B vitamins, but no vitamin C, vitamin B 2 or fat-soluble vitamins. The glucose tolerance factor (GTE) of yeast, chromium nicotinate, mediates the effect of insulin. It seems to be important for older persons who caimot synthesize GTE from inorganic dietary chromium. The ceU wall fraction of bakers yeast reduces cholesterol levels in rats fed a hypercholesteremic diet. 

Subcutaneous injection of insulin encapsulated in liposomes in rats resulted in prolonged hypoglycemic effects compared to a solution of free insulin this study also indicated that a substantial fraction of hand-shaken multilamellar vesicles could enter the circulation in intact form after subcutaneous injection (Stevenson et al., 1982). The neutral liposomes used in this study were cleared more slowly from the injection site than the negatively charged liposomes. 

Rice bran hemicelluloses reduce thymus atrophy in rats (Takenaka, 1992). Hikino et al. (1988) isolated and purified four glycan fractions from rice bran hemicelluloses and named them as Oryzabrans A, B, C, and D. All these glycans were shown to improve the peripheral utilization of insulin, resulting in significant hypoglycemic activity (Hikino et al., 1988 Hikino and Hayashi, 1989). Several investigations into rice bran polysaccharides and hemicelluloses (Masayoshi et al., 1987) have indicated a strong improvement in the immune... 

Equations (20) and (21) have been used to estimate the oral absorption of cefaclor, cefatrizine, and insulin. The simulated results compare favorably to the reported literature values in humans. The macroscopic mass balance approach provides a quick approximation to the fraction of dose absorbed and degraded for both passively and nonpassively absorbed drugs. 

Hydration of polymeric membranes may be influenced by the chemical identity of the polymers. A hydrophilic polymer has a higher potential to hydrate than a hydrophobic one. Sefton and Nishimura [56] studied the diffusive permeability of insulin in polyhydroxyethyl methacrylate (37.1% water), polyhydroxy-ethyl acrylate (51.8% water), polymethacrylic acid (67.5% water), and cupro-phane PT-150 membranes. They found that insulin diffusivity through polyacrylate membrane was directly related to the weight fraction of water in the membrane system under investigation (Fig. 17). 

Figure 17 Effect of weight fraction of water on insulin permeability of highly swollen polyacrylate membranes. (Reprinted with permission from Ref. 56.)...

Online LC-ESI-TOF-MS experiments are carried out in a very similar fashion to the off-line NPS-HPLC separations described above, with a few notable exceptions. Firstly, 0.3% (v/v) formic acid is added to each mobile phase to counteract the ionization suppression induced by TFA. Because of the formic acid UV detection must be carried out at 280 nm (as opposed to 214 nm). To aid in normalization between runs 1 jag of Bovine insulin (MW = 5734 Da) is added to each chromatofocusing fraction prior to injection onto the column. Finally, the flow is split postcolumn directing 200 JlL/min into the ion source and the remaining 300 JlL/min through the UV detector and fraction collection. 

As described above all samples were separated online using LCT ESI-TOF-MS then normalized for relative quantitation using a bovine insulin internal standard. Fractions were then collected for MAFDI-TOF-MS PMF, digested with modified porcine trypsin, and analyzed using the TofSpec2E. Following this analysis, three major classes of differentially expressed including proteins were revealed in these... 

Hormones have a profound effect on carbohydrate metabolism. Great interest has been aroused by reports of hormonal control of hexokinase activity by specific proteins in animal tissues.99- 100 Hexokinase action is the rate-limiting step in the uptake of D-glucose by muscle. Hexokinase is inhibited in diabetic muscle, but the inhibition can be partially reversed by insulin. A protein fraction from the anterior pituitary gland will inhibit the hexokinase of extracts of brain and muscle, and the effect of this... 

Many small proteins, in particular those that function extracellularly (e.g. insulin, GH and various cytokines) are quite stable and may be fractionated on a variety of HPLC columns without significant denaturation or decrease in bioactivity. Preparative HPLC is used in industrial-scale purification of insulin and of IL2. In contrast, many larger proteins (e.g. blood factor VIII) are relatively labile, and loss of activity due to protein denaturation may be observed upon high-pressure fractionation. 

Chromatographic or electrophoretic analysis of conventional insulins generally yields three major fractions or bands a, b and c). Fraction a contains high molecular mass material which can be removed from the product by additional recrystallization steps. The major components of fraction b are proinsulin and insulin dimers, while insulin, as well as slightly modified forms of insulin (e.g. arginine-insulin and desamido-insulin), are found in fraction c. 

Diabetogenic effect. Chromatographic fraction of the fresh stem, administered intragastrically to rats at a dose of 1 g/kg, was active. The fraction inhibited the elevation of semm TG, lipid peroxides, and insulin of rats fed on a high-sugar diet for 61 days . 

Kimura, Y., H. Okua, N. Shoji, T. Taemto, and S. Arichi. Effects of nonsugar fraction in black sugar on lipid and carbohydrate metabolism. Part II. New compounds inhibiting elevation of plasma insulin. Planta Med 1984 1984(5) 469-473. 

Increase unpredictably the circulating fraction of insulin and prolong its half-life a rare cause of insulin resistance... 

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