The cell membranes of cells existing on the earth utilizes phospholipids as the main component without exception. This seemingly universal phospholipids have a significantly different structure and composition depending on the species, tissue, organelle, etc., and is unevenly distributed. In recent years, ether-type phospholipids, which are unevenly distributed in humans, have attracted a great deal of attention as biomarkers for early detection of serious diseases, and are being actively studied. In this review, we will describe the discovery of several novel phospholipases that act specifically on unevenly distributed phospholipids and efforts toward its application.

Phospholipids are essential components of cell membranes in all organisms including animals, plants, fungi, and bacteria. Based on their molecular structures, phospholipids are classified into phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidic acid (PA), phosphatidylinositol (PI), phosphatidylglycerol (PG), cardiolipin (CL), sphingomyelin (SM), and so on. However, there has been no appropriate method for quantifying phsopholipid classes. Therefore, I have recently developed the enzymatic fluorometric assays to quantify all major phospholipid classes including PC, PE, PS, PA, PI, PG, CL, SM. These assays are simple, sensitive and high-throughput, but not time-consuming. These assays have been applied for the evaluation of the phos pholipid class compositions in cultured cells and their intracelluar organelles to investigate the func tions of enzymes and transporters. These enzymatic fluorometric assays will become key technologies for elucidating the biochemical and physiological roles of phospholipids in many fields of life sciences.

Plasmalogen is a subclass of phospholipids widely distributed in the biological world, from anaerobic bacteria to mammals. Although the pathophysiologic roles of Plasmalogen are poorly understood, it has long been implicated in a number of neurodegenerative disorders such as Alzheimer's disease. Recently, there have been various reports that changes of plasmalogen in the body are involved in metabolic diseases associated with oxidative stress and chronic inflammation. Thus, plasma/serum Plasmalogen is a potential biomarker for these diseases. Here we describe the relationship between plasmalogen and diseases, and the various reports from conventional to new methods of plasmalogen measurement.

Lipids are the main component of cellular membranes, function as energy storehouses and as important signaling molecules. Thus, alterations of membrane lipid homeostasis are linked to various diseases. Lipidomics is the large-scale study of the lipid produced in all living organisms and examine the structures, functions, interactions, dynamics of cellular lipids in the biological system. Lipidomics has been driven by rapid advances in technologies such as various chromatography technologies, mass spectrometry (MS), enzymatic fluorometric assays and protein probe methods. On the other hand, lipids are metabolically and chemically unstable, data errors and artifacts will occur without the accurate knowledge and techniques of analysis. In this review, I will share the important points of the work process of lipidomics based on MS technology and their experimental example.