ENZYMATIC AND ENVELOPE-CONVERTING ACTIVITIES OF PARS RECTA OVIDUCTAL FLUID FROM XENOPUS-LAEVIS

Conversion of the coelomic egg envelope to the vitelline envelope of the Xenopus laevis egg is known to take place in the pars recta (PR) region of the oviduct. A method for collecting fluid generated from PR cultured in vitro was devised which enhanced the recovery of envelope-converting factors. By the criteria of melting temperature analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, 125I labeling, ferritin binding, and in vitro fertilization assays, the secretions collected from PR cultured in vitro were capable of modifying the envelope in a manner analogous to that which occurred in vivo, including the limited hydrolysis of one envelope glycoprotein. Hydrolytic activities present in PR fluid were assayed with a number of peptide and carbohydrate substrates. Enzymes which hydrolyzed t-butyloxycarbonyl-Leu-Ser-Thr-Arg-methylcouma t-butyloxycarbonyl-Phe-Ser-Arg-methylcoumarylamide, and t-butyloxycarbonyl-Val-Leu-Lys-methylcoumarylamide were found to be present in PR fluid at levels elevated by threefold or more over amounts found in a comparable volume of blood plasma. © 1990.