Mass attenuation coefficients (μ/ρ) and molar extinction coefficients (ε) of gamma rays in some proteins, viz. Actin-N(C6H6N4O4), Collagen (C2H5NOC5H9NOC5H10NO2), Serum Amyloid P Component (C16H24N2O6), Arp 2/3(C17H16BrNO3S), CFTR Inhibitor IV,PPQ-102 (C26H22N4O3 ),CFTR Inhibitor 11.Gly H-101(C19H15Br2N3O3 ),Elastin(C27H48N6O6), C-reactive protein (C62H93N13O16), Myosin (C60H105N23O11), Serum albumin (C2936H4624N786O889S41), have been calculated at the photon energies 123, 360, 511, 662, 1170, 1280 and 1330 keV.The effective atomic number and electron density have also been derived and the results are discussed
