Proteins play key role in biochemical processes. Analysis of their structure and dynamics is crucial for understanding their action at a molecular level. Thus, the systems we have studied cover a wide selection of proteins: intrinsically unstructured proteins (IUPs), families of serine proteases and enzymes catalyzing phosphate ester hydrolysis. Examining structure and organization of protein building blocks and miniproteins helps us to understand more on the fundamentals of protein folding. Our basic tools are bioNMR, crystallography, CD- and IR-spectroscopic methods, quantum chemical calculations as well as chemical synthesis used for developing compounds of potential bioactivity.