Microparticulated Proteins

Another example is the purification of a P-lactam antibiotic, where process-scale reversed-phase separations began to be used around 1983 when suitable, high pressure process-scale equipment became available. A reversed-phase microparticulate (55—105 p.m particle size) C g siUca column, with a mobile phase of aqueous methanol having 0.1 Af ammonium phosphate at pH 5.3, was able to fractionate out impurities not readily removed by hquid—hquid extraction (37). Optimization of the separation resulted in recovery of product at 93% purity and 95% yield. This type of separation differs markedly from protein purification in feed concentration ( i 50 200 g/L for cefonicid vs 1 to 10 g/L for protein), molecular weight of impurities (<5000 compared to 10,000—100,000 for proteins), and throughputs ( i l-2 mg/(g stationary phasemin) compared to 0.01—0.1 mg/(gmin) for proteins). 

Fat Replacers. The reduction of fat in substitute dairy products results in an increase in water and a stress on the food system both in respect to body and texture, and to flavor. There is no universal fat replacer, but microparticulated proteins having particle sizes <10 fim and/or starch derivatives, and gums have been used as fat replacers. 

Whey proteins that have been heat precipitated under very high shear have a particle size between 1 and 3 micrometers, and give the impression of fat in some products. These microparticulated whey proteins are being used as fat replacers in frozen desserts and processed cheese substitutes. 

Alpert, A. J. and Regnier, F. E., Preparation of a porous microparticulate anion-exchange chromatography support for proteins, /. Chromatogr., 185, 375,1979. 

MJ Alonso. Nanoparticulate drug carrier technology. In S Cohen, H Bernstein, eds. Microparticulate Systems for the Delivery of Proteins and Vaccines. New York Marcel Dekker, 1996, pp 203-242. 

Microparticulate Systems for the Delivery of Proteins and Vaccines, edited by Smadar Cohen and Howard Bernstein... 

Add 100 pi of the NHS-iminobiotin solution to each ml of the antibody solution. Mix well to dissolve. Note Some turbidity may be present in the reaction due to incomplete dissolution of the NHS-iminobiotin. The solution may look cloudy or have a microparticulate suspension present. This is normal for many water-insoluble reagents when added to an aqueous solution in an organic solvent. As the reaction takes place, the NHS-iminobiotin will be driven into solution, both by coupling to the protein and by hydrolysis of the NHS ester. 

Microparticulate Systems for the Delivery of Proteins and Vaccines, edited by Smadar Cohen and Howard Bernstein Good Manufacturing Practices for Pharmaceuticals A Plan for Total Quality Control, Fourth Edition, Revised and Expanded, Sidney H. Willig and James R. Stoker... 

The thickness of the mucus layer in the human stomach is about 570 pm [101], whereas in the human colon the thickness is about 100-150 pm [102], Ryu and Grim [103] suggested that there is little mixing between the villi and the unstirred layer over the tip of the villi of the canine jejunum, which is about 500-1000 pm thick. Therefore, for a solute to reach the lateral surfaces of the villi, an additional barrier of as much as 800 pm needs to be traversed [103]. It was shown that native mucus gel from rat small intestine reduced the diffusion coefficients of 3H-water, urea, benzoic acid, antipyrine, aminopyrine, alpha-methyl-glucoside, L-phenylalanine by 37%-53% compared with buffer solution [104], For high-molecular-weight substances, such as proteins or microparticulates, mucin can offer considerable resistance to diffusion [105],... 

Different drug delivery systems have been proposed for vaginal delivery of peptides and proteins. The first one was a mucoadhesive gel based on polyacrylic acid intended for vaginal administration of insulin [96]. More recently, microparticulate systems such as starch and hyaluronan ester (HYAFF) microspheres have been proposed for vaginal delivery of insulin... 

Sampson, H.A., Cooke, S. 1992. The antigenicity and allergenicity of microparticulated proteins Simplesse . Clin Exp Allergy 22 963-969. 

In peptide/protein pharmaceuticals, the GAS process is predominantly applied for the preparation of microparticulate protein powders as an alternative to common drying processes. However, Winters et al. [69] reported an increase of P-sheet aggregates during the precipitation of lysozyme, trypsin, and insulin as a consequence of stress parameters such as organic solvent, pressure, and shear forces. One reason... 

Winters, M. A., Debenedetti, P. G., Carey, J., Sparks, H. G., Sane, S. U., and Przybycien, T. M. (1997), Long-term and high-temperature storage of supercritically-processed microparticulate protein powders, Pharm. Res., 14,1370-1378. 

Schwendeman, S. P, Cardamone, M., Klibanov, A., and Langer, R. (1996), Stability of proteins and their delivery from biodegradable polymer microspheres, in Cohen, S., and Bernstein, H., Eds., Microparticulates Systems for the Delivery of Proteins and Vaccines, Marcel Dekker, New York, pp. 1 49. 

---