Large protein complexes carry out some of the most complex activities in biology1,2. Such structures are often assembled spontaneously through the process of self-assembly and have characteristic chemical or biological assets in the cellular mechanisms3. Gold-based nanomaterials have attracted much attention in many areas of chemistry, physics and biosciences because of their size- and shape-dependent optic, electric, and catalytic properties. Here we report for the first time a one step synthesis in which Manganese Superoxide Dismutase protein plays a key role in the reduction of gold salts via the use of a Good's buffer (HEPES) to produce gold nanoparticles, compared to other proteins as catalase (CAT) and bovine serum albumin (BSA).We prove that this effect is directly related with the biological activities of the proteins that have an effect on the gold reduction mechanisms. Such synthesis route also induces the integration of proteins directly in the AuNPs that are intrinsically safe by design using a one-step production method. This is an important finding that will have uses in various applications, particularly in the green synthesis of novel nanomaterials.