We investigated the influence of the projectile size and energy using Au-n(q+) clusters (5 < n < 400, 1 < q < 4) impacting on a glycine target with a 19q-34q keV energy range. We show that both CN- fragment and Gly(-) molecular ion yields are equivalent for projectiles with n > 9 and increase with the energy per projectile atoms. A maximum yield of 0.5 (50%) for both CN- and Gly(-) was obtained with the Au-400(4+) projectile at 136 keV total energy. For Gly(-), the yield enhancement is linear for Au-n when n > 5. Trends for the CN- fragment are different. A nonlinear yield enhancement proportional to n(3) is observed for Au-n when n < 9. (c) 2006 Elsevier B.V. All rights reserved.