Structure and function of alpha-fetoprotein: a biophysical overview.

alpha-Fetoprotein (AFP) is a large serum glycoprotein belonging to the intriguing class of onco-developmental proteins. AFP has attracted considerable attention since it was shown that the change in its serum level during pregnancy is a hallmark of the development of numerous embryonic disorders, while the increase in its content in the plasma of adults correlates with the appearance of several pathological conditions. Over the past 30 years, some 11000 papers have been published concerning AFP, an average rate of over a publication a day since 1969. The majority of publications are about the application of the protein in diagnostics, or about other uses of AFP in biomedicine; though some of them describe the biochemical and functional properties of AFP, two aspects have been extensively reviewed. However, surprisingly little is currently known about structural properties of this protein as well as about the molecular mechanism of its function. The present review pursues the aim to describe the current state of the art in studies of structural properties and conformational stability of AFP. An attempt to establish the relationship between conformational transformations in AFP and its function is also made.