The small, basic, water-soluble napins are one of the two major kinds of storage proteins synthesized in the seed during its maturation. Inhibits cell-free protein synthesis. Has antibacterial activity against Gram-negative bacterium P.fluorescens, and the Gram-positive bacteria B.subtilis, B.cereus, B.megaterium and M.phei. No antibacterial activity against the Gram-positive bacterium S.aureus or the Gram-negative bacteria E.coli, E.aerogenes and P.aeruginosa. The mature protein consists of a small and a large chain linked by disulfide bonds. Belongs to the 2S seed storage albumins family.