  Networks of tryptophan -- an aromatic amino acid with strong fluorescent
response -- are ubiquitous in biological systems, forming diverse architectures
in transmembrane proteins, cytoskeletal filaments, sub-neuronal elements,
photoreceptor complexes, virion capsids, and other cellular structures. We
analyze the cooperative effects induced by ultraviolet (UV) excitation of
several biologically relevant tryptophan mega-networks, thus giving insight
into novel mechanisms for cellular signalling and control. Our theoretical
analysis in the single-excitation manifold predicts the formation of strongly
superradiant states due to collective interactions among organized arrangements
of up to more than $10^5$ tryptophan UV-excited transition dipoles in
microtubule architectures, which leads to an enhancement of the fluorescence
quantum yield that is confirmed by our experiments. We demonstrate the observed
consequences of this superradiant behavior in the fluorescence quantum yield
for hierarchically organized tubulin structures, which increases in different
geometric regimes at thermal equilibrium before saturation -- highlighting the
effect's persistence in the presence of disorder.
