scleroprotein
Concise Oxford English Dictionary © 2008 Oxford University Press:
scleroprotein /ˌsklɪərə(ʊ)ˈprəʊtiːn, ˌsklɛ-/
▶noun Biochemistry an insoluble structural protein such as keratin, collagen, or elastin.
'scleroprotein' also found in these Oxford entries:

