A mitogenic defensin from white cloud beans (Phaseolus vulgaris)

A peptide, with a molecular mass of 7458 Da, was purified from the seeds of white cloud beans (Phaseolus vulgaris cv. ‘white cloud bean’). This peptide was isolated using a simple protocol consisting of affinity chromatography on Affi-gel blue gel and gel filtration on Superdex 75. The peptide had both antifungal and antibacterial activities. It reduced the activity of HIV-1 reverse transcriptase and it also inhibited translation in a cell-free rabbit reticulocyte lysate system. Its antifungal activity was retained after incubation with trypsin but was reduced when the ambient ionic strength was raised. The peptide elicited a mitogenic response from mouse splenocytes but did not stimulate nitric oxide production in mouse macrophages.