Mass transport kinetics of the DNA-binding dye Hoechst-33342 into bovine spermatozoa.
The mass transport kinetics for the unmediated diffusion of Hoechst-33342 dye (HO-33342) into spermatozoa was established at varying pH and temperature. The mass transport diffusion coefficient k(diff) at 41.5 degrees C and pH 6.2 was determined to be 0.0435min(-1) [M sperm/mL](-1) and the energy of activation E(a) associated with the temperature dependency of k(diff) at 14.2kcal/gmoL. The relationship of k(diff) to pH was based mechanistically on the premise that the HO-33342 dye becomes more hydrophobic as the pH becomes more alkaline and therefore facilitates transport. The k(diff) dependency on pH was described mathematically using a form of the Henderson-Hasselbalch equation in which the pKa of the HO-33342 dye was 6.6. Using the kinetic parameters, an Excel-based model was developed capable of predicting the time required for the HO-33342 dye to reach any specified level of saturation in the spermatozoa.
Monsanto Company, 800 N. Lindbergh Blvd., St. Louis, MO 63167, USA. robert.b.weisenfeld@monsanto.com
Robert B
RB
Weisenfeld
D000818:Animals; D001562:Benzimidazoles / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D001692:Biological Transport; D002417:Cattle; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004058:Diffusion; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008163:Luminescent Measurements; D008297:Male; D013094:Spermatozoa / Q000502:physiology*; D013696:Temperature
D001562:Benzimidazoles; D005456:Fluorescent Dyes; D004247:DNA; C017807:bisbenzimide ethoxide trihydrochloride