In the post genomic era, as more and more genome sequences are becoming known and hectic efforts are underway to decode the information content in them, it is becoming increasingly evident that flexibility in proteins plays a crucial role in many of the biological functions. Many proteins have intrinsic disorder, either wholly or in specific regions. It appears that this disorder may be important for regulatory functions of the proteins, on the one hand, or, may help in directing the folding process to reach the compact native state, on the other. Nuclear Magnetic Resonane (NMR) has over the last two decades emerged as the sole, most powerful technique to help characterize these disordered protein systems. In this review, we first discuss the significance of disorder in proteins and then survey the NMR methods available for their characterization. A brief description of the results obtained on several disordered proteins is presented at the end
