Monolithic bioreactors: Effect of chymotrypsin immobilization on its biocatalytic properties

The effect of different modes of α-chymotrypsin attachment to the surface of methacrylate-based ultrashort monolithic minicolumns on enzyme activity has been studied. The immobilization of protease was carried out via direct covalent binding of chymotrypsin, as well as via its attachment through small and polymer spacers. It was established that the lowest enzyme activity against N-benzoyl-l-tyrosine ethyl ester was found for bioreactor obtained via direct attachment of chymotrypsin to the surface of GMA–EDMA minidisks, whereas the highest parameter close to that determined for dissolved enzyme was found in the case of bioreactor prepared by the introduction of copolymer of 2-deoxy-N-methacryloylamido-d-glucose with N-vinylpyrrolidone and acrolein as a long and flexible polymer spacer. Additionally, the effect of flow rate of substrate recirculation on bioconversion efficiency was examined. Independently on immobilization method, the increase of flow rate led to the raise of biocatalytic efficiency.     

Monoclonal antibodies to an artificial immunogen, specifically demonstrating phosphotyrosine-containing proteins

The importance of protein phosphorylation at tyrosyl hydroxy groups in the control of cell proliferation has recently been established. For identification of tyrosine-phosphorylated proteins, monoclonal antibodies (Mabs) against artificial immunogens containing O-phosphotyrosine (pTyr) or tripeptide pTyr-Gly-Gly as haptens were generated; the haptens were coupled to carrier proteins (bovine serum albumin, human immunoglobulin, keyhole limpet hemocyanin). After immunization of mice with pTyr coupled to keyhole limpet hemocyanin, Mabs were generated which were highly specific for pTyr and did not cross-react with O-phosphoserine, O-phosphothreonine, tyrosine or nucleoside-5'-monophosphates. The Mabs specifically react with tyrosinephosphorylated proteins in the Rous sarcoma virus-transformed rat XC-cell.     

Prolactin messenger ribonucleic acid concentrations throughout the ovine estrous cycle: assessment relative to prolactin serum and pituitary amounts

Prolactin (PRL) mRNA concentrations were assessed by nucleic acid hybridization assays in pituitaries of ewes representing the defined stages of the ovine estrous cycle. Concomitantly, pituitary and serum PRL concentrations were measured in these ewes using radioimmunoassays. It was observed that PRL serum, pituitary and mRNA concentrations tended to increase near the time of the gonadotropin preovulatory surge, particularly between 24 hrs before behavioral estrus to 5 hours after estrus. However, the changes in PRL mRNA, serum and pituitary concentrations were shown not to be statistically significant. These data suggest that PRL production during the sheep estrous cycle is maintained without dramatic changes in synthesis or secretion.