Structure of DL-Serine Phosphate Monohydrate: an Intermediate Phosphate Bonding System exhibiting Very Short Hydrogen Bonds

Abstract

SERINE phosphate is one of the most widespread of amino-acid phosphates found in living systems. The phosphoproteins, casein (from milk) and vitellin (from egg yolk), contain large amounts of serine phosphate. The phosphodiester of serine, phosphatidylserine, is an important phospholipid found in cell membranes. Thus serine is probably the only amino-acid found incorporated both in the membrane lipids and membrane proteins. The suggestion has been made that this versatility of serine is a result of its β-hydroxyamine structure, which appears to be a common structural feature of the major phospholipids and spbingolipids¹. Furthermore, it has been found that the β-hydroxyamine chain, , assumes a gauche conformation in crystal structures. This structure determination was undertaken as part of a series of studies on the structures of biological phosphates. The results of this work show that DL-serine phosphate is also in the gauche conformation. An outstanding feature of this structure is the presence of two very short hydrogen bonds between symmetry-related phosphate groups.