English to Spanish Science Biology (-tech,-chem,micro-) biochemistry

Saludos.
Por favor si alguien puede traducir correctamente el termino.
Creo que la primera parte se traduce como °núcleo central°.
Gracias por su trabajo.


How Bacillus thuringiensis has
evolved specific toxins to colonize the
insect world

… The C-terminal extension found in the longer protoxins is not part
of the active toxin (it is digested by proteases in the
insect gut, see Fig. 2a), but it is believed to have
a role in the formation of the crystal1. The threedimensional
structures of three activated forms of Bt
toxins, a Cry1 (Ref. 7), a Cry2 and a Cry3 (Ref. 8),
have been solved by X-ray crystallography and are
remarkably similar, each consisting of three domains
(Fig. 2b). The N-terminal domain I consists of seven
α-helices (six amphipathic helices around a central
core helix). Domain II is a so-called ‘β-prism’, with
three-fold symmetry consisting of three β-sheets
having a ‘Greek key’ conformation. The C-terminal
domain III consists of two antiparallel β-sheets
in a ‘jelly-roll’ formation. Domain I is involved in
membrane insertion and pore formation. Domains II
and III are both involved in receptor recognition and
binding. Additionally, a role for domain III in pore
function has been found.