Mass Spectrometry in the Study of Hemoglobin: from Covalent Structure to Higher Order Assembly

Abstract

Hemoglobins are dioxygen transport proteins, which are universally present in higher vertebrates as a tetrameric protein. Recently there has been much interest in mutations and posttranslational modifications to hemoglobins as these may be directly implicated in disease states like thalassemia and diabetes mellitius. The analysis of covalent adducts to hemoglobin provides information on the extent of exposure to many carcinogenic compounds. Studies of the assembly of hemoglobins from mammalian sources are being pursued for their clinical use as blood transfusion products. Over the past several years, numerous developments in mass spectrometry (MS) methods and instrumentation have revolutionized the analysis of proteins from their primary sequences to the quaternary structures of large oligomeric complexes. This review provides a summary of the uses of mass spectrometry in the analysis of hemoglobins, in particular, tetrameric hemoglobins. It presents some results of novel mass spectrometric studies on hemoglobins on all levels of protein structure and assembly, and interaction with other biomolecules. Full and partial sequencing by MS in the analysis of hemoglobin mutations, posttranslational modifications and chemical modifications; analyses of hemoglobin structures, dynamics and assembly; and analyses of hemoglobin interactions with other biomolecules of clinical importance are discussed. The review will conclude with a discussion of the utility of MS techniques in hemoglobin analyses, where the field is headed, and possible areas for improvement.