Formation of the Native Topology of a Protein is due to the "Conserved but Non-Functional" Residues: A Case of Apomyoglobin Folding.

This paper is dedicated to the memory of Oleg B. Ptitsyn (1929-1999) and presents an answer to his question: "What is the role of conserved non-functional residues in protein folding?". This answer follows from the experimental works of three labs. The role of non-functional but conserved residues of apomyoglobin (apoMb) in the formation of the native protein fold in the molten globule state has been experimentally revealed. This research proves that the non-functional but conserved residues of apoMb are necessary for the formation and maintenance of the correct topological arrangement of the main elements in the apoMb secondary structure already in the early folding intermediate.