passages.id: split_4_test_1441_passage
passages.type: progene_text
passages.text: The kinetics of the 3beta-hydroxysteroid dehydrogenase ( 3betaHSD ) and 17betaHSD2 activities using cell homogenate protein of stably transfected 293 cells indicated that the catalytic efficiency ( apparent catalytic efficiency = maximum velocity / Km ) of this 3betaHSD activity is approximately 2000 - fold ( pregnenolone as substrate ) or 3000 - fold ( DHEA as substrate ) weaker than that of 17betaHSD2 activity .