Studies of fish zona pellucida by high-performance ion-exchange chromatography on agarose columns and free zone electrophoresis

Quantitative Evaluation of Dielectric Breakdown of Silicon Micro- and Nanofluidic Devices for Electrophoretic Transport of a Single DNA Molecule

In the present study, we quantitatively evaluated dielectric breakdown in silicon-based micro- and nanofluidic devices under practical electrophoretic conditions by changing the thickness of the insulating layer. At higher buffer concentration, a silicon nanofluidic device with a 100 nm or 250 nm silicon dioxide layer tolerated dielectric breakdown up to ca. 10 V/cm, thereby allowing successful electrophoretic migration of a single DNA molecule through a nanochannel. The observed DNA migration behavior suggested that parameters, such as thickness of the insulating layer, tolerance of dielectric breakdown, and bonding status of silicon and glass substrate, should be optimized to achieve successful electrophoretic transport of a DNA molecule through a nanopore for nanopore-based DNA sequencing applications.

Cycloaliphatic epoxy resin coating for capillary electrophoresis

Coating the interior surface of a fused-silica capillary with a polymeric material has long been used in capillary electrophoresis (CE) to reduce or eliminate electroosmotic flow and suppress adsorption. A cycloaliphatic epoxide-based resin was bonded to silane treated capillaries and crosslinked with a curing agent. The epoxy resin coating significantly reduced electroosmotic flow over a pH range of 3-10. This coating was sufficiently hydrophilic to suppress protein adsorption. The epoxy resin coated capillary was used to separate several acidic and basic proteins and peptides. Separation efficiencies greater than 400,000 theoretical plates were achieved. The relative standard deviations in migration times for proteins were <0.8%. Speed and simplicity are important advantages of the coating procedure compared to other published coating methods.

Common egg envelope antigens are limited to the animal class

The antigens of the egg envelope (zona pellucida) in mammals are of special interest because of their possible involvement in immunoinfertility and as candidate targets for immunocontraception. Conserved zona epitopes from divergent species may present a suitable source and an animal model for investigation of the above factors. We compared egg envelope antigens from 6 species of vertebrates belonging to 3 different classes in order to demonstrate the existence of shared antigens. Egg envelopes from the trout, carp, turtle, hen, duck and quail were isolated and heat-solubilized. They were tested with rabbit polyclonal antisera against carp, trout and duck egg envelopes by the enzyme-linked immunosorbent assay. The results showed significant cross-reactions among egg envelopes of fish and birds. The examined solubilized preparations did not show cross-reactivity with egg envelopes from any other class, suggesting that divergent species did not share common egg envelope antigens, and that their use may not be appropriate in the investigation of immunoinfertility and immunocontraception in humans.

The major structural proteins of cod (Gadus morhua) eggshells and protein crosslinking during teleost egg hardening

The highly hydrophobic protein aggregate which constitutes the fish eggshell has for the first time been quantitatively solubilized. This study shows that the nonactivated eggshell from cod is composed primarily of only three protein monomers, designated alpha (74 kDa) beta (54 kDa) and gamma (47 kDa). Protein extraction studies of the eggshells before and after egg activation demonstrate that egg hardening is accompanied by a 10-fold decline in total protein solubility, which is due to nonextraction of the alpha, beta, and gamma chains. When present during the egg activation process monodansylcadaverine (MDC-a fluorescent lysine analog) inhibits eggshell hardening and at the same time becomes covalently incorporated into the eggshell. This MDC incorporation is calcium-dependent and suggests the induction of a perivitelline transglutaminase activity after egg activation. (Transglutaminases catalyze the formation of an amide bond (isopeptide bond) between the gamma-carbonyl group of glutamine and the epsilon-amino group of lysine with release of ammonia. Crosslinks between proteins are generated when the two amino acid residues are located on different proteins.) Protein solubilization studies and NaDodSO4 gel analysis of the eggshell proteins from eggs subjected to 5 mM MDC during egg activation, reveal that when eggshell hardening is blocked by MDC, the three main eggshell proteins remain extractable even after egg activation. Simultaneously we observed a covalent incorporation of MDC into the gamma protein.

Protein-carbohydrate complementarity in mammalian gamete recognition

Recent studies suggest that gamete recognition in a number of species is mediated by complementary proteins and carbohydrates on opposing gamete surfaces. Studies in invertebrates and vertebrates have shown that carbohydrate-binding proteins on the sperm surface recognize and bind to complementary glycoconjugates on the egg's extracellular coat. This chapter reviews our current knowledge of gamete recognition in the mouse. The complementary receptors for both mouse sperm and egg have been identified, purified, and characterized. Their synthesis during gametogenesis has been defined, as have the effects of sperm capacitation and of the acrosome reaction on their expression and distribution. Their relationship to gamete receptors that function in other species is discussed. Finally, evidence is presented that suggests that one of the receptors that mediate mouse gamete recognition belongs to a family of cell surface receptors that function during multiple cellular interactions in development.

Polyclonal antibodies to a 32-kDa deglycosylated polypeptide from porcine zonae pellucidae will prevent human gamete interaction in vitro

The major deglycosylated polypeptides of the porcine zona pellucida (ZP), with molecular masses of 66, 52, 36, and 32 kDa, were purified to homogeneity with one-dimensional sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS/PAGE). Immunofluorescence studies demonstrated that antibodies to the DGZP fraction, and the 66- and 32-kDa polypeptides, bound predominantly to the outer ZP; however, only the first two of these antisera formed an immunoprecipitate around the outer human ZP. In immunoblotting experiments using polyclonal antisera raised to these molecules all four polypeptides exhibited cross-reactivity with each other and their parental glycoprotein families (ZP 1-4). In addition, the antisera were tested in an in vitro human gamete bioassay to determine their contraceptive potential; antibodies to the 32-kDa deglycosylated polypeptide inhibited human gamete interaction to the greatest extent, 5.3% (+/- 1.2%), relative to a control value of 100%.

Application of high-performance chromatographic and electrophoretic methods to the purification and characterization of glucose oxidase and catalase from Penicillium chrysogenum

The high resolving power of the preparative and analytical high-performance chromatographic and electrophoretic methods recently developed in this laboratory for the separation of biopolymers has been demonstrated by the purification and characterization of glucose oxidase and catalase from Penicillium chrysogenum. Crude glucose oxidase was purified to homogeneity in one step by high-performance hydrophobic-interaction chromatography (HIC) on a pentylagarose column. Crude catalase was purified by a combination of HIC and high-performance anion-exchange chromatography on 3-diethylamino-2-hydroxypropylagarose. The homogeneity of the enzymes was monitored by high-performance electrophoresis and free zone electrophoresis. The pI values of these two enzymes determined by isoelectric focusing in the high-performance electrophoresis apparatus were 4.2 and 6.5, respectively. Their molecular weights were determined by high-performance molecular sieve chromatography on an agarose column. Glucose oxidase has a molecular weight of 175,000 and probably consists of two identical subunits, as sodium dodecyl sulphate polyacrylamide gel electrophoresis gave a molecular weight of around 72,000. The molecular weight of catalase, which is probably composed of non-identical subunits, as indicated by sodium dodecyl sulphate electrophoresis, is around 320,000. Some other characteristics of these two enzymes were also investigated, e.g., electrophoretic mobility, pH stability and optimum pH.

Analysis of the biological properties of antibodies raised against intact and deglycosylated porcine zonae pellucidae

Zonae pellucidae (ZP) were isolated from 1,500 porcine ovaries and heat solubilized to generate approximately 15 mg ZP glycoprotein. Analysis of this material by isoelectric focusing, one-dimensional electrophoresis, and gas chromatography indicated the presence of a major glycoprotein species that exhibited considerable microheterogeneity with respect to its charge (pI 7.5-3.5) and molecular mass (45-85 kDa) and that contained 39.6% carbohydrate, predominantly N-acetylglucosamine. Chemical deglycosylation of porcine ZP using trifluoromethanesulphonic acid (TFMS) resulted in the production of five discrete protein bands on one-dimensional sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS/PAGE) with molecular masses of 66, 52, 36, 32, and 16 kDa. Antisera raised in rabbits and marmosets to ZP and/or deglycosylated ZP (DGZP) were used in immunoblotting experiments to demonstrate the retention of immunogenicity by DGZP and the cross-reactivity of the antisera with their heterologous antigen. These studies indicated that antisera that were capable of inhibiting the fertility of primates in vivo and the penetration of the human ZP in vitro reacted preferentially with 3 of the 5 products of deglycosylation, with molecular masses of 66, 52, and 36 kDa. Anti-DGZP antibodies were also shown to interact with intact porcine and human ZP and, with the latter, to block the ability of human spermatozoa to both bind to and penetrate this structure.

Gradient and isocratic high-performance liquid chromatography of proteins on a new agarose-based anion exchanger

We describe a new, simple, and mild method for the preparation of anion-exchangers, based on the coupling of alkylamines to epoxy-activated agarose (prepared by the reaction of agarose with butanediol diglycidyl ether). Since a polar OH-group is formed when an epoxide reacts with an OH or NH2 group, the ion-exchanger did not show any hydrophobic interaction. This is important, since it may be impossible to desorb a protein from an ion exchanger having a hydrophobic character, because increasing the salt concentration of the eluent to decrease the electrostatic binding inevitably strengthens the hydrophobic interaction. By the method described, 3-diethylamino-2-hydroxy-propyl agarose (DEAHP-agarose) was prepared. High resolution of proteins was obtained by gradient elution at both high and low degrees of substitution. However, isocratic separations required a low degree of substitution, in accordance with a hypothesis previously put forward in connection with a theoretical and experimental study of the conditions for isocratic elution of macromolecules on amphiphilic gels. A study of the retention times of several proteins at different pH levels and buffer compositions indicated that different pH levels should be tested for maximal resolution and that, in many cases, the best resolution can be obtained if the DEAHP-agarose is operated in a buffer containing sodium acetate instead of sodium chloride. A quaternary amine agarose, 3-methyldiethylamino-2-hydroxy-propyl agarose (QAE-agarose), can be synthesized easily from DEAHP-agarose by alkylation with methyl iodide. The titration curves of DEAHP-agarose and QAE-agarose showed pK values around 9.5 and 11.3, respectively.