This thesis focuses on protein structure, dynamics and interaction and their relation to human disease. In particular, the biophysical and structural properties of both well-ordered and partially disordered proteins are studied using a range of biophysical techniques such as circular dichroism spectroscopy, fluorescence spectroscopy, mass spectrometry and nuclear magnetic resonance spectroscopy. Pseudomonas aeruginosa is a human pathogen due to its multidrug resistance (MDR) caused by overexpression of efflux pump systems. This thesis describes how MDR mutations within the MexR repressor of the MexAB-OprM system reduce the DNA affinity by altering its stability with maintained structure. The oncogenic protein c-Myc is involved in many essential biological functions such as cell proliferation, differentiation and apoptosis and is also highly associated with several forms of human cancers, and where the N-terminal domain is regulated by a plethora of protein interactions. In this thesis the intrinsically disordered N-terminal part of c-Myc and its interactions with the proteins Bin1 and TBP are described. Myc binds Bin1 with maintained disorder in a multivalent manner, which may explain why the onco-protein can interact with such a wide range of binding partners. A similarly dynamic interaction is observed for Myc with the TATA-binding protein (TBP). The essential human multidomain glutaredoxin Grx3 is associated with several biological functions such as redox signaling, proliferation and signal transduction. We have solved the structure and analyzed the dynamic properties in the ps-ns and ms time scale for the two N-terminal domains, providing a platform for further analysis of the Grx3 protein and its interactions. Taken together, this thesis emphasizes the importance of joint structural, biophysical and dynamic studies to better understand protein function in health and disease.