Two-dimensional correlation Raman spectroscopy for characterizing protein structure and dynamics

Since the initial introduction of the basic concept almost twenty years ago, two-dimensional correlation spectroscopy (2DCoS) has become a popular analytical tool applicable to a broad range of science problems. Vibrational spectroscopy remains the major area of 2DCoS applications where infrared spectroscopy is the most popular technique followed by Raman and Near Infrared spectroscopies. An increasing number of publications over the past few years have established Raman 2DCoS as a powerful problem solving technique in protein studies. In this review we provide a critical survey of recent protein studies using the 2DCoS Raman approach. We also analyze common misconceptions and potential pitfalls in the interpretation of 2D correlation data. Over the past decade, there have been a number of publications pointing to artifacts associated with visualization and interpretation of 2D correlation maps. We demonstrate here how some of the 'artifacts' of the 2DCoS approach in-reality turn into the strength of the method.