boron and boromycin

Boromycin is a macrodiolide that exists as a hydrophobic Böeseken complex formed from boric acid and a chiral polyhydroxy macrocyclic ligand. It was covalently bonded to silica gel through a urea linkage to an attached d-valine ester. When evaluated as a chiral stationary phase, it shows pronounced enantioselectivity toward primary amine-containing racemates, separating 98% of those tested. The selectivity is most pronounced in the presence of organic solvents and supercritical CO2 + methanol. The enantioselective binding site and mechanistic factors are examined. Analytes can be complexed as either the free base or their protonated analogues, with the free base being more strongly associated with the chiral selector.

Topics: Amines; Binding Sites; Borates; Boron; Carbon Dioxide; Chromatography, High Pressure Liquid; Chromatography, Supercritical Fluid; Methanol; Models, Molecular; Molecular Structure; Sensitivity and Specificity; Solvents; Stereoisomerism; Time Factors

Fusion of capacitated spermatozoa with the vitelline membrane, but not actual penetration, appears to initiate the cortical reaction in hamster eggs. The reaction can be artificially induced by the application of positively charged particles to the vitelline surface, a situation which may normally be prevented by the zona pellucida. Exposure of hamster eggs to neuraminidase, to lectins (concanavalin A and phytohaemagglutinin-P), to a monovalent ionophore (boromycin) and to 1,3-bis(4-chlorocinnamylideneamino)guanidine elicits a cortical granule discharge resulting in a block to fertilization. These agents all appear to act by inducing depolarization of the vitelline membrane.

Topics: Animals; Borates; Boron; Cricetinae; Female; Fertilization; Guanidines; In Vitro Techniques; Ionophores; Lectins; Male; Membrane Potentials; Neuraminidase; Ovum; Sperm-Ovum Interactions; Spermatozoa; Vitelline Membrane; Zona Pellucida

Topics: Anti-Bacterial Agents; Borates; Boron; Hydrolysis