X-Ray Crystallographic Studies of Immunoglobulins

Abstract

The techniques of X-ray crystallography have been successfully applied to the study of complex biological polymers such as nucleic acids and proteins. These studies have provided structural models from which we have tried to explain the mechanisms of DNA replication, of enzyme action, and of other biological phenomena. The determination of the structure of several crystalline enzymes, achieved within the last ten years, is an outstanding example of this approach. As a result of such efforts, models have been obtained for the highly specific interactions between enzymes and their substrates. Development of methods and techniques has reached the point at which it is now possible to attempt the determination of more complex structures such as those of immunoglobulins. It is hoped that a knowledge of the three-dimensional structure of immunoglobulins will provide a useful model for the correlation of their function and primary structure and the genetic control of variability and specificity of antibodies. This article is a review of the first models of immunoglobulin structure obtained by X-ray crystallographic methods. A brief outline of some aspects of the structure and properties of immunoglobulins and the theoretical and practical aspects of protein crystallography will be presented first. The most detailed account to be given in this review will be that of the Fab structure which is currently under study in the author’s laboratory.