Abnormally glycosylated IgA leads to IgA nephropathy, the most common cause of renal failure. IgG antibody represents one-third of new drugs currently in development, and its conformational stability under various conditions is essential for biopharmaceuticals. We will identify the solution structures of human IgA and IgG in a range of buffers. We will apply our powerful constrained scattering modelling approach to reveal conformational changes in these antibodies that are crucial to disease and biotechnology. We are also investigating the solution structures of complexes formed between the major complement regulator factor H and its target C3b. Complement C3 undergo large conformational changes to form C3b, which shows different domain arrangements for C3b in its crystal structures. We will identify the C3b solution structure to clarify its mechanism of action.