Purification and characterization of transglutaminases from the genital tract of the male rat

Abstract

In the genital tract of the male rat two different forms of the enzyme transglutaminase (TGase) could be identified and characterized. The coagulating gland and the dorsal prostate secrete a glycosylated and acylated TGase with a molecular weight of 65,000 dalton and pI value of 8.7. This secretory form was purified to homogeneity using preparative isoelectric focusing and gel filtration on a Superdex 200 column. Running fast protein liquid chromatographic gel filtration on a Superose 12 column in the presence of calcium ions, high-molecular-weight aggregates were physically formed which could only be eluted using drastic conditions (0.1 M sodium hydroxide). In the presence of 10 mM EDTA this tendency to aggregate was greatly diminished. Utilizing a Superdex 200 column for gel filtration, the secretory TGase was even eluted as a monomeric protein. Testicular TGase was isolated by ion-exchange fast protein liquid chromatography on a Mono Q and by gel filtration on a Superdex 200 column. This enzyme represents a tissue-type TGase with a molecular weight of 82,000 dalton and pI value of 5.25. Hydrophobic interaction chromatography on a phenyl-Superose column showed no further enrichment of the GTP-binding form of transglutaminase.