Protein uptake

The method utilizing ID NMR is simple and eonvenient. Henee the NMR method diseussed here ean be applied to the systematie investigation of the membrane irug inter-aetions, elosely related to the vital function in biomembranes. It is expected that the application can be extended to the lipid-peptide interaction and protein uptake. We are now applying the method to apolipoprotein binding with lipid bilayers and emulsions. Preferential protein binding sites in membranes can be specified by NMR on the molecular level. 

M Narawane, VHL Lee. (1992). Hormonal and oxidative control of protein uptake by the conjunctiva of the pigmented rabbit. Invest Ophthalmol Vis Sci 33(Suppl) 733. 

Sheep / Lucerne extract [AD]. ( ). D Increased protein uptake attributed to dietary tannins in certain circumstances. 

The maximum adsorption (deposition) of three proteins on rhombohedral hematite (SA = 19 m g ) ranged from 5 to 20 mg m (Johnson and Matijevic, 1992 a), and, for ovalbumin and y-globuline occurred near their iep 4.7 and 6.8, respectively. For lysozyme, however, the highest adsorption occurred at pH 9, much below its iep (11.0) and was probably due to strong intermolecular association of the protein (minimum solubility) at this pH. Protein uptake may depend on the number and kind of amino acids in the protein as well was on their association and conformational behaviour. 

Peptide/protein uptake rates across the nasal epithelia are dependent upon molecular mass. Relatively small peptides, such as oxytocin, desmopressin and LHRH analogues, cross relatively easily and several such products used medically are routinely delivered nasally. Larger molecules (of molecular mass greater than 10 kDa) generally do not cross the epithelial barrier without the concurrent administration of detergent-like uptake enhancers. Long-term use of enhancers is prohibited due to their damaging cellular effects. 

In order to be exploitable for extraction and purification of proteins/enzymes, RMs should exhibit two characteristic features. First, they should be capable of solubilizing proteins selectively. This protein uptake is referred to as forward extraction. Second, they should be able to release these proteins into aqueous phase so that a quantitative recovery of the purified protein can be obtained, which is referred to as back extraction. A schematic representation of protein solubilization in RMs from aqueous phase is shown in Fig. 2. In a number of recent publications, extraction and purification of proteins (both forward and back extraction) has been demonstrated using various reverse micellar systems [44,46-48]. In Table 2, exclusively various enzymes/proteins that are extracted using RMs as well as the stability and conformational studies of various enzymes in RMs are summarized. The studies revealed that the extraction process is generally controlled by various factors such as concentration and type of surfactant, pH and ionic strength of the aqueous phase, concentration and type of CO-surfactants, salts, charge of the protein, temperature, water content, size and shape of reverse micelles, etc. By manipulating these parameters selective sepa-... 

Transfer of solubihzed proteins from the reverse micellar phase back to an aqueous phase constitutes back extraction. A successful RME should include both forward and back extraction processes in their optimized conditions. In contrast to the extensive studies investigating the forward extraction process, back extraction has been addressed to a much lesser extent. Most of the earlier studies tacitly assume that conditions, which normally prevent protein uptake in the forward transfer, would promote their release in the back transfer. That is to select a pH and salt condition that had minimal forward transfer efficiency. This... 

Zampieri et al. [ 149], in order to circumvent the inherent problems of the earlier sedimentation studies, employed two different dyes (one water soluble and the other strong interfacially active) to monitor the association of water and surfactant with empty and filled RMs independently. They were able to estimate the sizes of filled and empty RMs based on water, protein, and surfactant balances by determining the individual Wg values for the two types of RMs. The conclusions arrived at were in sharp contrast to those of Levashov et al. [148], as it was shown that both the filled and empty RMs increased in size with the overall Wg and that neither the filled nor the empty RM size was the same after protein uptake. An assumption made by Zampieri et al. [149] is that the two dyes distributed between the RMs in proportion to water and surfactant, respectively. Hatton s group [152] suggested that this assumption may not be true based on their analyses of the substrate distribution effects and suggested that the statistical distribution of solutes over the micelle population may be skewed to one or the other of two types of RMs. 

Maestro, M. and Luisi, P. L. (1990). A simplified thermodynamic model for protein uptake by reverse micelles. In Surfactants in Solution, ed. K. L. Mittal. Plenum, vol. 9. 

Applying Eq. (16) to BSA the diffusion coefficient in free solution can be calculated as 7.3-10 11 m2/s, as shown by Skidmore et al. [66], however, this value was by a factor of 8.6 smaller when diffusion of BSA in a porous adsorbent was determined from batch protein uptake in a stirred tank. Diffusion of large... 

Muller M, Kessler B, Adler H-J et al (2004) Reversible switching of protein uptake and release at polyelectrolyte multilayers detected by ATR-FTIR spectroscopy. Macromol Symp 210 157-164... 

Proteins destined for import into the nucleus typically require a nuclear localization signal, four to eight amino acids long, located internally in the protein. Uptake occurs via nuclear pores and requires ATP hydrolysis. 

Does Membrane-Partitioning Play a Major Role in Protein Uptake and Intracellular Routing ... 

Roth, T.F., Porter, K.R. Yolk protein uptake in the oocyte of the mosquito Aedes aegypti. J Cell Biol 20 (1964) 313-330. 

Tentoxin. AUernarla alternata produces tentoxin [61], a cyclic tetrapeptide. This phytotoxin causes Injury to many monocotyledonous and dicotyledonous weed species, but does not Injure maize (Zea mavs L.) or soybean (GTvcIne L. Nerr.) (29). Tentoxin has been synthesized In the lab (212) Sites of action of this toxin are disruption of energy transfer by Inhibition of CFi ATPase (211) and alteration of nuclear-coded protein uptake (2341. 

T Growth factor in insects, and reported to increase protein uptake in rats, later identified as a mixture of folic acid, vitamin B12, and nucleotides U Methylsulfonium salts of methionine... 

Two-Site Assay Protocol for the Measurement of Human a-Fetopro-tein. Purified antibodies to human a-fetoprotein (AFP) are prepared by allowing 1 ml of high titer antiserum (binding capacity approximately 125 p,g of AFP per milliliter) to react with 1 mg of AFP immunoadsorbent (protein uptake 120 p,g per milligram of cellulose) for 48 hr at 4°. Elution of high affinity antibody is carried out as described above for the preparation of purified insulin antibody. The antibody solution is diluted to 100 ml in 50 vaM sodium hydrogen carbonate buffer (pH 9.6) and used to coat 500 plastic tubes as described above. 

The JHE model was constructed in order to better test hypotheses of catalytic activity, substrate preference and protein uptake. It will also allow us to improve our ability to rationally design modified forms of JHE as a biologically based insecticide. This model was built using both acetylcholinesterase from T californica and lipase from G. candidum as templates and is consistent with the principles of protein structure. 

Carbomer is also compatible with dimethyl sulfoxide. The veterinary product, Domoso (Syntex Veterinary Labs), is a topical gel consisting of carbomer 934 and 90% dimethyl sulfoxide. Carbomer 940 gels exhibit superior optical clarity compared with 934 gels, and can be used in ophthalmic preparations. However, only carbomer 934 is approved for internal use. The mucoadhesive properties of carbomer were studied with triamcinolone acetonide, with acyclovir and to improve protein uptake across the nasal mucosa. Pharmaceutical gel products containing carbomer in their formulations are listed in Table 6. All are dermatological gels except for Anbesol Gel (Whitehall) and Pilopine HS (Alcon). 

Robertson WG. The effect of high animal protein uptake on the risk of calcium stone formation In the urinary tract. Clln.Scl. 1979 57(3) 285-8. 

T Growth factor in insects, and reported to increase protein uptake in rats, later... 

Protein typically is well tolerated as a caloric source in SBS patients. For those SBS patients on EN it is controversial what molecular form of the macronutrient maximizes protein absorption. In the past, EN often was initiated with elemental products that contained free amino acids as the protein source because the efficiency of protein uptake was perceived to be better. However, total protein absorption is faster and more complete with dipeptide and tripeptide formulations. It appears that the absorption of free amino acids by the enteral route is a saturable process, whereas the absorption of small peptides is not. These more complex protein sources also may stimulate intestinal adaptation. ... 

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