Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
- Publication Type
Articles 1 - 2 of 2
Full-Text Articles in Structural Biology
Conformational And Circular Dichroism Studies On N-Acetyl-L-Prolyl-D-Alanyl-Methylamide, S. Ramaprasad
Conformational And Circular Dichroism Studies On N-Acetyl-L-Prolyl-D-Alanyl-Methylamide, S. Ramaprasad
Journal of the Arkansas Academy of Science
The compact ordered conformations of the molecule N-Acteyl-L-Prolyl-D-Alanyl-Methylamide have been studied by semiempirical energy calculations in vacuum and circular dichroism (CD) in solution. The presence of ordered structure has been observed in hydrogen bond promoting solvents like trifluoroethanol by CD studies. In hydrogen bond breaking solvents, like trifluoroacetic acid (TFA), significant fraction of the ordered conformers probably assume extended conformation without intramolecular hydrogen bonds and perhaps are in equilibrium with the fraction of compact ordered structures. The trend observed in going from nonpolar to polar solvent is also compatible with the previous NMR studies in solution. The semiempirical energy calculations …
Progesterone And 17 Α-Hydroxyprogesterone: Novel Stimulators Of Calcium Influx In Human Sperm, Peter F. Blackmore, Stephen J. Beebe, Douglas R. Danforth, Nancy Alexander
Progesterone And 17 Α-Hydroxyprogesterone: Novel Stimulators Of Calcium Influx In Human Sperm, Peter F. Blackmore, Stephen J. Beebe, Douglas R. Danforth, Nancy Alexander
Bioelectrics Publications
Progesterone and 17 alpha-hydroxyprogesterone (but not other steroids such as testosterone, corticosterone, beta-estradiol, estrone, dehydroepiandrosterone, 20 alpha-hydroxypregnen-3-one, androstenedione, and pregnenolone) were shown to cause an immediate increase, in free cytosolic calcium ([Ca2+]i) in both capacitated and noncapacitated human sperm, using the fluorescent indicator fura 2. Significant increases in [Ca2+]i were observed with 10 ng/ml progesterone, while maximum effects were seen with 1 microgram/ml progesterone. Two other steroids 11 beta-hydroxyprogesterone and 5 alpha-pregnane-3,20-dione exhibited significant activity to increase [Ca2+]i. This increase in [Ca2+]i elicited by progesterone was entirely due to Ca2+ influx from the extracellular medium since the increase in [Ca2+]i …