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To develop empirical models for predicting the binding between a drug and beta-cyclodextrin. Specifically, the logarithm of the 1:1 binding constant is expressed as the function of various molecular descriptors of the drug. Many potential drugs exhibit poor aqueous solubility. Also, the amount available for solubility studies is limited early in drug development. Thus, models that show which excipients can increase a drug's solubility are useful because formulation scientists can focus on them experimentally.Twenty-five descriptors were considered based on molecular characteristics governing complexation. These include the drug's size and/or shape, the dispersion of its electron cloud, its lipophilicity, and its flexibility. The training set contains 258 ligands, ranging from drug-like molecules to small polar organic compounds.Two models were developed. The first is derived by partial least squares regression and consists of all 25 descriptors. The r2 determined by cross-validation is 0.79. The second contains four variables and was constructed by multiple linear regression. Its cross-validated r2 is 0.65.Due to its simplicity, the second model is recommended over the first. The most important descriptor in both models is the calculated log P, indicating that drugs with greater lipophilicity form stronger complexes with beta-cyclodextrin.

Self-interaction of macromolecules has been shown to play an important role in a number of physical processes, including crystallization, solubility, viscosity, and aggregation. Peptide self-interaction is not as well studied as for larger proteins, but should play an equally important role. The osmotic second virial coefficient, B, can be used to quantify peptide and protein self-interaction. B values are typically measured using static light scattering (SLS). Peptides, however, do not scatter enough light to allow such measurements. This study describes the first use of self-interaction chromatography (SIC) for the measurement of peptide B values because SIC does not have the molecular size limitations of SLS. In the present work, SIC was used to measure B for enfuvirtide, a 36-amino acid therapeutic peptide, as a function of salt concentration, salt type, and pH. B was found to correlate strongly with solubility and apparent molecular weight. In general, the solubility of enfuvirtide increases with pH from 6 to 10 and decreases as the salt concentration increases from 0 to 0.5M for three different salts. The effect of peptide concentration on B was also investigated and shown to have a significant effect, but only at high concentrations (>80 mg/mL).

OB protein (or leptin) administration causes a long-lasting reduction in food intake and body weight in obese ob/ob mice. Neuropeptide Y, a stimulator of feeding, has been proposed to be a major mediator of the biological actions of OB protein. To test this hypothesis, the interaction of brain administration of exogenous OB protein and NPY on the feeding behavior of ob/ob mice was examined. Human OB protein, in a dose-dependent manner, partially or completely blocked feeding induced by exogenous NPY. These results demonstrate that OB protein can functionally antagonize and dominate the actions of exogenous NPY on feeding.

A method is described to enhance the resolution and detection sensitivity of proteins, peptides, and amino acids in capillary electrophoretic analysis of solution mixtures. The method consists of derivatizing the analytes with fluorescamine, which is normally used as a fluorogenic reagent for compounds containing a reactive primary amine functional group, and then using the derivative as an ultraviolet chromophore to enhance detection sensitivity (measured at 280 nm) in capillary electrophoresis. The results demonstrated a significant improvement in the separation and detection sensitivity of the derivatized analytes as compared to their underivatized counterparts. The use of chromophores, such as fluorescamine, in capillary electrophoresis facilitates the analysis of components of solution mixtures, such as pharmaceutical formulations, that could not be resolved and/or detected by conventional capillary electrophoresis procedures.

A quantitative spectrophotometrc assay for the determination of proline and hydroxyproline is described. The assay is based on the derivatization of the imino acids with the fluorogenic chromophore fluorescamine and the separation of the derivatized analytes by capillary electrophoresis. Fluorescamine reacts efficiently with secondary amino acids to form nonfluorescent aminoenone type chromophores which are easily detected at the low UV region. The assay is simple, rapid, and offers a significant improvement in detection sensitivity when compared with standard colorimotric methods for determining these imino acids. Derivatization with fluorescamine also enhances the degree of resolution of the two imino acids, enabling baseline separation of the derivatized analytes.

Several methods are available for determining the components present in a typical pharmaceutical dosage form. Although some of these methods are simple and have received wide pharmaceutical industry acceptance over many years, several limitations still need to be overcome. Capillary electrophoresis was examined as an alternative method for the determination of a recombinant cytokine in a pharmaceutical dosage form. The results show that capillary electrophoresis can separate the recombinant cytokine from its dosage form matrix adequately, rapidly and with minimum sample volume requirements. Owing to its high efficiency, high resolution and simplicity, capillary electrophoresis appears to be very applicable to pharmaceutical samples. For reliable quantification of the resulting data, however, it is essential to optimize the experimental conditions, such as separation buffer and capillary column temperature. The advantages and potential of capillary electrophoresis for the separation of active ingredients and excipients in pharmaceutical formulations are discussed.

Due to the fact that some proteins have a tendency to bind to glass surfaces, plastic CZ-resin vials were evaluated as an alternative material to glass vials for packaging protein-based parenteral formulations. Physico-chemical tests including protein binding, extractable evaluation, oxygen permeation, light transmission and moisture loss were performed. Data show that two proteins (A and B) were found to bind to USP type I glass but not to CZ-resin. The CZ-resin vials passed all USP test specifications for extractables (organic extractable, non-volatile residue and residue on ignition). The oxygen permeation rate (79.06 cm(3)mm/m(2)24 h atm) was consistent with that reported by the vendor (67 cm(3)mm/m(2)24 h atm). The value obtained for light transmission, which was also found to be consistent with that reported by the vendor, shows that these vials offer no protection from light. The average moisture loss from 2 cm(3) vials filled with water was gravimetrically determined to be 0.04 mg/day/vial when the vials were stored at 40 degrees C/75% relative humidity (RH). Assuming a 1cm(3) product fill, this corresponds to approximately a 3% loss over a 2-year period. However, moisture loss was found to be negligible at the typical storage condition of 5 degrees C for protein formulations. The physico-chemical tests indicate that CZ-resin vial is a suitable candidate for packaging parenteral formulations since it shows low moisture loss at typical storage condition of 5 degrees C, and does not leach out extractables. However, it should not be used for light-sensitive and oxygen-sensitive parenteral formulations. For proteins A and B, the CZ-resin vial is a viable alternate to the use of glass vials since it offered significantly less protein binding. Protein binding in general, should be evaluated on a case by case basis, since it may vary for different proteins and under different formulation conditions.

Capillary electrophoresis has proved to be a versatile method for the determination of proteins, peptides and amino acids in pharmaceutical formulations. For quantification of the capillary electrophoresis data, however, significant errors may result if the analysis is performed using improper separation conditions. The peak area response for protein analytes, which is generally low in conventional UV detection, may also vary dramatically depending on the nature of the buffer used in the separation. This paper describes the effects of various buffer constituents and analytical conditions on the capillary electrophoretic separation and quantification of a humanized monoclonal antibody in bulk form and in a typical therapeutic formulation. For optimum peak area response and reproducibility, protein derivatization with an appropriate chromophore (e.g., fluorescamine) and separation in the presence of a moderate ionic strength buffer containing lithium chloride, tetramethylammonium chloride or trimethylammonium propylsulfonate is recommended. General guidelines for the determination of proteins by capillary electrophoresis and a rationale for the use of internal standards to improve the quantification of data are also discussed.

A cDNA coding for human interleukin 2 (IL-2) was inserted into the genome of Autographa californica nuclear polyhedrosis virus adjacent to the polyhedrin promoter. Cells infected with recombinant virus produced high levels of Mr 15,500 IL-2 polypeptide, the majority of which was secreted into the culture medium during infection. The recombinant IL-2 was able to stimulate the growth of an IL-2-dependent cell line. The N-terminal amino acid sequence of the insect-derived IL-2 was identical to that of natural IL-2. Thus, a mammalian signal peptide was recognized and properly removed in insect cells.

A purified glycoprotein, designated RSL-major, was isolated from the rat sublingual gland by means of the procedure of Tettamanti and Pigman. It was found to be homogeneous by analytical ultracentrifugation, to have a mol. wt. of 2-2 times 10-6, and to contain 81 percent (W/W) of carbohydrate, which consists mainly of sialic acid, 2-acetamido-2-deocy-D-glucose, 2-acetamido-2-deocy-D-galactose, and D-galactose in the molar ratio of 1.4:1.4:1.0:1.5; small amounts of fucose and mannose [1.2 and 2.8 percent (W/W), respectively] were also present. The sialic acid residues were resistant to the action of V. cholerae neuraminidase. This resistance was completely abolished by removal of the O-acetyl groups contained in the sialic acid. The sialic acid in RSL-major appeared to be a mixture of N-acetyl-4-O-acetyl- and N-acetyl-4, 7(8)-di-O-acetylneuraminic acids. The carbohydrate to protein attachment of RSL-major was shown, by alkaline beta-elimination reaction, to consist of an O-glycosyl linkage between 2-acetamido-2-deoxy-D-galactosyl residues in the oligosaccharide chains and seryl and threonyl residues in the protein core. The average oligosaccharide, contained in RSL-major, was postulated to be a heptasaccharide. A second material, designated RSL-minor, and also isolated from the ratsublingual gland, was obtained as a mixture of glycoprotein(s) and hydroxylapatite gel, and was not purified further.

When translated in the wheat germ system, mRNA from fresh calf thymus stimulates incorporation of radioactive amino acids into an acid-insoluble product, and 10--20% of the total radioactivity incorporated is precipitated with antisera to active thymosin fractions. In sodium dodecyl sulfate disc gel electrophoresis, radioactivity was recovered mainly in two peptides, corresponding to 16,000 and 11,000 daltons; the latter probably represents incomplete chains. Tryptic digests of each of these peptides yielded fragments corresponding to the sequence of residues 15--19 of thymosin alpha1; these peptides were characterized by cochromatography with digests of synthetic thymosin alpha1 and by Edman degradation. Thus, the 16,000-dalton peptide synthesized in the cell-free system appears to be q precursor of thymosin alpha1 and possibly of other peptides in the fractions isolated from calf thymus. The results support the conclusion that this peptide is synthesized in the thymus gland.

The visco-elastic properties of salivary secretions are due to high molecular-weight glycoproteins, known as mucins. Mucins are composed of numerous oligosaccharide side-chains O-glycosidically linked through 2-acetamido-2-deoxy-alpha-D-galactose to the hydroxyl groups of seryl and threonyl residues of the protein core; on the average, every fourth amino acid residue is involved in such a bond. This work conveys their isolation and purification, compiles the compositional analysis of several mammalian submaxillary and sublingual mucins; defines the conditions of the alkaline beta-elimination reaction, its mechanism, and importance in structural studies of glycoprotens, and briefly discusses the influence of stimuli on mucous secretions, as well as biosynthesis, structural diversity, and physiological role of salivary mucous glycoproteins.

Publisher Summary This chapter discusses the nature of the protein core of bovine, ovine, and porcine submaxillary mucins and describes its implications for protein synthesis. Protein biosynthesis occurs by a two-step mechanism involving the formation of small peptides at the ribosomes and their assembly by polymerases at the Golgi membrane. The existence of homologous peptides and proteins in the mucins from individual glands has important consequences for the concept of evolutionary processes. The lack of blood group activity for the inactive mucin can be expected to arise from the presence of carbohydrate chains shorter than for those for the H and A types. A limited number of synthesizing sites for peptides, containing 16 to 30 amino acids, can produce a pool of peptides from which an unlimited number of proteins can be assembled at a specific enzyme site for each protein. Specific short sequences needed for a particular function—for example, the basic chains of histones—can be separately synthesized and incorporated.

Bovine submaxillary mucin, after removal of its sialic acid component, is cleaved by trypsin into two principal glycopeptide fractions; their final yield corresponds to 70% by weight of the original mucin and 85% of the original amount of hexosamine in the mucin. These glycopeptides have amino acid and carbohydrate compositions that are very similar to those of the original and desialyzed mucin. The main glycopeptide contains about 28 amino acids; the second one seems to be a covalently linked trimer of the former and is resistant to further action by trypsin. The protein core of bovine submaxillary mucin is composed mainly of several hundred covalently bound sequences of these glycopeptides. These results are compatible with those reported by Downs and Pigman (1969) for the products obtained by chemical cleavage of this mucin.

It has been shown that dimethylsulfoxide is useful in separating protein contaminants and minor mucins from the submaxillary glycoproteins prepared by the method of Tettamanti, G. and Pigman, W. (1968) Arch. Biochem. Biophys., 124, 41–50. In addition, alkaline dimethylsulfoxide was found to greatly accelerate the β-elimination reaction of glycoproteins. As this procedure does not produce diffusible protein fragments, it should be of value in studies of the protein core and for the investigation of those protein-carbohydrate linkages that are resistant to treatment by alkali. Optimal conditions for carrying out the β-elimination and reduction reactions of bovine submaxillary glycoprotein in aqueous alkaline NaBH4 systems have been described. Under such conditions, the conversion of 2-aminopropenoic and 2-amino-2-butenoic acid residues into alanine and α-aminobutyric acid, respectively, is complete. This reduction procedure is of a broad application and can be used for the reduction of the phenylhydrazone derivatives of α-keto acids to the corresponding amino acids. A comparison of our procedure with that described by Simpson, L. D., Hranisavljevic, J. and Davidson, E. A. (1972) Biochemistry, 11, 1849–1856, shows that the method outlined here is superior both in efficiency and for quantitative recovery of unsaturated hydroxyamino acids.