Protein complexity is exponentially increased by posttranslational modifications (PTMs). A delicate balance between attachment and removal of PTMs controls fundamental cellular processes such as transcription and cell signaling and can lead to disease if it malfunctions, making it crucial to understand at a molecular level how PTMs control protein functions. My research aims to combine chemical protein synthesis with structural biology to understand how PTMs lead to structural changes that result in functional changes in proteins. Chemical protein synthesis can provide unique access to site-specifically modified and segmentally labelled proteins, and NMR spectroscopy can provide structural, dynamic and mechanistic information on proteins at atomic resolution. Here, we use HMGN1 as a model intrinsically disordered protein – a high mobility group nucleosome-binding protein involved in remodeling chromatin and regulating transcription. PTMs are known to affect the distribution of HMGN1 in the cell, its binding to nucleosomes and the modification of histones H1 and H3. Using site-specifically modified and segmentally labelled HMGN1 variants, we study the effects of PTMs on the structural and dynamic properties of HMGN1 using NMR spectroscopy. Integrating chemical protein synthesis with structural biology allows us to gain new insights into the effects of PTMs on protein structure, dynamics and regulation of biological activity.