  Patchy particles are considered to be a good model for protein aggregation.
We calculate the equilibrium phase diagram of two-patch colloidal particles
undergoing aggregation along with isotropic potential. This investigation
demonstrates the coexistence of different phases like disordered clusters,
chains, crystals and bundles depending on the relative strength of isotropic
and anisotropic potential, these phases are also reported for glucose isomerase
proteins. We also show that the formation of network of bundles is metastable
against the formation of thermodynamically favored finite sized bundles, which
are also metastable along with thermodynamically stable crystals. These bundles
appear to be helical in structure similar to that observed in sickle cell
hemoglobin.
