In many cases they are synthesised as part of a larger precursor protein, either as a prepropeptide or as an N-terminal domain associated with an inactive peptidase or zymogen.

[4][5] The structure of the Kazal repeat includes a large quantity of extended chain, 2 short alpha-helices and a 3-stranded anti-parallel beta sheet.

[5] Altering the enzyme-contact residues, and especially that of the active site bond, affects the strength of inhibition and specificity of the inhibitor for particular serine proteases.

Kazal domains often occur in tandem arrays and have a central alpha-helix, a short two-stranded antiparallel beta-sheet and several disulphide bonds.

[7][8][9] The amino terminal segment of this domain binds to the active site of its target proteases, thus inhibiting their function.